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Search found 112 results on 5 pages for 'comparator'.

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  • When is @uncheckedVariance needed in Scala, and why is it used in GenericTraversableTemplate?

    - by retronym
    @uncheckedVariance can be used to bridge the gap between Scala's declaration site variance annotations and Java's invariant generics. scala import java.util.Comparator import java.util.Comparator scala trait Foo[T] extends Comparator[T] defined trait Foo scala trait Foo[-T] extends Comparator[T] :5: error: contravariant type T occurs in invariant position in type [-T]java.lang.Object with java.util.Comparator[T] of trait Foo trait Foo[-T] extends Comparator[T] ^ scala import annotation.unchecked._ import annotation.unchecked._ scala trait Foo[-T] extends Comparator[T @uncheckedVariance] defined trait Foo This says that java.util.Comparator is naturally contra-variant, that is the type parameter T appears in parameters and never in a return type. Which begs the question, why is it also used in the Scala collections library: trait GenericTraversableTemplate[+A, +CC[X] <: Traversable[X]] extends HasNewBuilder[A, CC[A] @uncheckedVariance] What are the valid uses for this annotation?

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  • List<> own comparer

    - by netmajor
    I have a List where element is: struct element { double priority; int value; } How can I implement my own comparer which allow me sort List by priority ? I try with SortredList... but it don't allow douplicated keys :( Big thanks for help!

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  • Unchecked call to compareTo

    - by Dave Jarvis
    Background Create a Map that can be sorted by value. Problem The code executes as expected, but does not compile cleanly: http://pastebin.com/bWhbHQmT The syntax for passing Comparable as a generic parameter along to the Map.Entry<K, V> (where V must be Comparable?) -- so that the (Comparable) typecast shown in the warning can be dropped -- eludes me. Warning Compiler's cantankerous complaint: SortableValueMap.java:24: warning: [unchecked] unchecked call to compareTo(T) as a member of the raw type java.lang.Comparable return ((Comparable)entry1.getValue()).compareTo( entry2.getValue() ); Question How can the code be changed to compile without any warnings (without suppressing them while compiling with -Xlint:unchecked)? Related TreeMap sort by value How to sort a Map on the values in Java? http://paaloliver.wordpress.com/2006/01/24/sorting-maps-in-java/ Thank you!

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  • C++ string sort like a human being?

    - by Walter Nissen
    I would like to sort alphanumeric strings the way a human being would sort them. I.e., "A2" comes before "A10", and "a" certainly comes before "Z"! Is there any way to do with without writing a mini-parser? Ideally it would also put "A1B1" before "A1B10". I see the question "Natural (human alpha-numeric) sort in Microsoft SQL 2005" with a possible answer, but it uses various library functions, as does "Sorting Strings for Humans with IComparer". Below is a test case that currently fails: #include <set> #include <iterator> #include <iostream> #include <vector> #include <cassert> template <typename T> struct LexicographicSort { inline bool operator() (const T& lhs, const T& rhs) const{ std::ostringstream s1,s2; s1 << toLower(lhs); s2 << toLower(rhs); bool less = s1.str() < s2.str(); std::cout<<s1.str()<<" "<<s2.str()<<" "<<less<<"\n"; return less; } inline std::string toLower(const std::string& str) const { std::string newString(""); for (std::string::const_iterator charIt = str.begin(); charIt!=str.end();++charIt) { newString.push_back(std::tolower(*charIt)); } return newString; } }; int main(void) { const std::string reference[5] = {"ab","B","c1","c2","c10"}; std::vector<std::string> referenceStrings(&(reference[0]), &(reference[5])); //Insert in reverse order so we know they get sorted std::set<std::string,LexicographicSort<std::string> > strings(referenceStrings.rbegin(), referenceStrings.rend()); std::cout<<"Items:\n"; std::copy(strings.begin(), strings.end(), std::ostream_iterator<std::string>(std::cout, "\n")); std::vector<std::string> sortedStrings(strings.begin(), strings.end()); assert(sortedStrings == referenceStrings); }

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  • Virtual methods as Comp function to sort

    - by wilsongoncalo.mp
    Hello everyone! I'm new to C++ and i'm trying to use std::sort function to sort a vector of Solutions. The code is something like this (solution list is a *vector): void SolutionSet::sort(Comparator &comparator) { std::sort(solutionsList_->begin(), solutionsList_->end(), &comparator::compare); } The comparator param is a Comparator´s child class instance , and the compare method is virtual at Comparator class and implemented by all Comparator's child classes. And i want to use that function as a comparator function at std:sort(). Is this possible? If it is, can someone tell me how? Because with the previous code, it doesn't work. If i've not made myself clear, please just ask! Thank you guys!

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  • Controlling the order in which files get processed

    - by [email protected]
    The File/Ftp Adapter allows you to control the order in which files get processed. For example, you might want the files to be processed in order of their modified times/ file sizes etc. Luckily, the File/Ftp adapters allow you to achieve this via a "FileSorter" attribute that you can define in the JCA file for your inbound File/Ftp Adapter service.   The File/Ftp Adapters ship with two predefined sorters that use the last modified times e.g.   However, there are times when you would like to define the order yourself. In situations like this, you can implement a Java Comparator and register the comparator with the File Adapter as described below: 1) Write a comparator. For example, the FileSizeSorter comparator sorts the files in descending order of their sizes:   2) In order to compile this class though, you will need fileAdapter.jar in the classpath.  

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  • Why are there two implementations of std::sort (with and without a comparator) rather than one implementation with a default template parameter?

    - by PolyVox
    In my code I'm adopting a design strategy which is similar to some standard library algorithms in that the exact behavior can be customized by a function object. The simplest example is std::sort, where a function object can control how the comparison is made between objects. I notice that the Visual C++ provides two implementations of std::sort, which naturally involves code duplication. I would have imagined that it was instead possible to have only one implementation, and provide a default comparator (using operator< ) as a default template parameter. What is the rational behind two separate versions? Would my suggestion make the interface more complex in some way? Or result in confusing error messages when the object does not provide operator Thanks, David

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  • Java List Sorting: Is there a way to keep a list permantly sorted automatically like TreeMap?

    - by david
    In Java you can build up an ArrayList with items and then call: Collections.sort(list, comparator); Is there anyway to pass in the Comparator at the time of List creation like you can do with TreeMap? The goal is to be able add an element to the list and instead of having it automatically appended to the end of the list, the list would keep itself sorted based on the Comparator and insert the new element at the index determined by the Comparator. So basically the list might have to re-sort upon every new element added. Is there anyway to achieve this in this way with the Comparator or by some other similar means? Thanks.

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  • Variable function name Javascript.

    - by Vladimir
    I'm sorting array: myArray.sort(comparators.some_comparator); and I have several comparator to choose from: comparators = { asc_firstname_comparator : function(o1, o2){ ... } desc_firstname_comparator : function(o1, o2){ ... } etc... } I want to write function which returns certain comparator depending on input data. It should figure out comparator from string inputs, something like this: function chooseComparator(field, order){ return "comparators."+order+"_"+field+"_comparator"; } So is it possible to pass only function name string to sort() method or I'll need to pass reference to correct comparator somehow?

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  • HPET for x86 BSP (how to build it for WCE8)

    - by Werner Willemsens
    Originally posted on: http://geekswithblogs.net/WernerWillemsens/archive/2014/08/02/157895.aspx"I needed a timer". That is how we started a few blogs ago our series about APIC and ACPI. Well, here it is. HPET (High Precision Event Timer) was introduced by Intel in early 2000 to: Replace old style Intel 8253 (1981!) and 8254 timers Support more accurate timers that could be used for multimedia purposes. Hence Microsoft and Intel sometimes refers to HPET as Multimedia timers. An HPET chip consists of a 64-bit up-counter (main counter) counting at a frequency of at least 10 MHz, and a set of (at least three, up to 256) comparators. These comparators are 32- or 64-bit wide. The HPET is discoverable via ACPI. The HPET circuit in recent Intel platforms is integrated into the SouthBridge chip (e.g. 82801) All HPET timers should support one-shot interrupt programming, while optionally they can support periodic interrupts. In most Intel SouthBridges I worked with, there are three HPET timers. TIMER0 supports both one-shot and periodic mode, while TIMER1 and TIMER2 are one-shot only. Each HPET timer can generate interrupts, both in old-style PIC mode and in APIC mode. However in PIC mode, interrupts cannot freely be chosen. Typically IRQ11 is available and cannot be shared with any other interrupt! Which makes the HPET in PIC mode virtually unusable. In APIC mode however more IRQs are available and can be shared with other interrupt generating devices. (Check the datasheet of your SouthBridge) Because of this higher level of freedom, I created the APIC BSP (see previous posts). The HPET driver code that I present you here uses this APIC mode. Hpet.reg [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\Hpet] "Dll"="Hpet.dll" "Prefix"="HPT" "Order"=dword:10 "IsrDll"="giisr.dll" "IsrHandler"="ISRHandler" "Priority256"=dword:50 Because HPET does not reside on the PCI bus, but can be found through ACPI as a memory mapped device, you don't need to specify the "Class", "SubClass", "ProgIF" and other PCI related registry keys that you typically find for PCI devices. If a driver needs to run its internal thread(s) at a certain priority level, by convention in Windows CE you add the "Priority256" registry key. Through this key you can easily play with the driver's thread priority for better response and timer accuracy. See later. Hpet.cpp (Hpet.dll) This cpp file contains the complete HPET driver code. The file is part of a folder that you typically integrate in your BSP (\src\drivers\Hpet). It is written as sample (example) code, you most likely want to change this code to your specific needs. There are two sets of #define's that I use to control how the driver works. _TRIGGER_EVENT or _TRIGGER_SEMAPHORE: _TRIGGER_EVENT will let your driver trigger a Windows CE Event when the timer expires, _TRIGGER_SEMAPHORE will trigger a Windows CE counting Semaphore. The latter guarantees that no events get lost in case your application cannot always process the triggers fast enough. _TIMER0 or _TIMER2: both timers will trigger an event or semaphore periodically. _TIMER0 will use a periodic HPET timer interrupt, while _TIMER2 will reprogram a one-shot HPET timer after each interrupt. The one-shot approach is interesting if the frequency you wish to generate is not an even multiple of the HPET main counter frequency. The sample code uses an algorithm to generate a more correct frequency over a longer period (by reducing rounding errors). _TIMER1 is not used in the sample source code. HPT_Init() will locate the HPET I/O memory space, setup the HPET counter (_TIMER0 or _TIMER2) and install the Interrupt Service Thread (IST). Upon timer expiration, the IST will run and on its turn will generate a Windows CE Event or Semaphore. In case of _TIMER2 a new one-shot comparator value is calculated and set for the timer. The IRQ of the HPET timers are programmed to IRQ22, but you can choose typically from 20-23. The TIMERn_INT_ROUT_CAP bits in the TIMn_CONF register will tell you what IRQs you can choose from. HPT_IOControl() can be used to set a new HPET counter frequency (actually you configure the counter timeout value in microseconds), start and stop the timer, and request the current HPET counter value. The latter is interesting because the Windows CE QueryPerformanceCounter() and QueryPerformanceFrequency() APIs implement the same functionality, albeit based on other counter implementations. HpetDrvIst() contains the IST code. DWORD WINAPI HpetDrvIst(LPVOID lpArg) { psHpetDeviceContext pHwContext = (psHpetDeviceContext)lpArg; DWORD mainCount = READDWORD(pHwContext->g_hpet_va, GenCapIDReg + 4); // Main Counter Tick period (fempto sec 10E-15) DWORD i = 0; while (1) { WaitForSingleObject(pHwContext->g_isrEvent, INFINITE); #if defined(_TRIGGER_SEMAPHORE) LONG p = 0; BOOL b = ReleaseSemaphore(pHwContext->g_triggerEvent, 1, &p); #elif defined(_TRIGGER_EVENT) BOOL b = SetEvent(pHwContext->g_triggerEvent); #else #pragma error("Unknown TRIGGER") #endif #if defined(_TIMER0) DWORD currentCount = READDWORD(pHwContext->g_hpet_va, MainCounterReg); DWORD comparator = READDWORD(pHwContext->g_hpet_va, Tim0_ComparatorReg + 0); SETBIT(pHwContext->g_hpet_va, GenIntStaReg, 0); // clear interrupt on HPET level InterruptDone(pHwContext->g_sysIntr); // clear interrupt on OS level _LOGMSG(ZONE_INTERRUPT, (L"%s: HpetDrvIst 0 %06d %08X %08X", pHwContext->g_id, i++, currentCount, comparator)); #elif defined(_TIMER2) DWORD currentCount = READDWORD(pHwContext->g_hpet_va, MainCounterReg); DWORD previousComparator = READDWORD(pHwContext->g_hpet_va, Tim2_ComparatorReg + 0); pHwContext->g_counter2.QuadPart += pHwContext->g_comparator.QuadPart; // increment virtual counter (higher accuracy) DWORD comparator = (DWORD)(pHwContext->g_counter2.QuadPart >> 8); // "round" to real value WRITEDWORD(pHwContext->g_hpet_va, Tim2_ComparatorReg + 0, comparator); SETBIT(pHwContext->g_hpet_va, GenIntStaReg, 2); // clear interrupt on HPET level InterruptDone(pHwContext->g_sysIntr); // clear interrupt on OS level _LOGMSG(ZONE_INTERRUPT, (L"%s: HpetDrvIst 2 %06d %08X %08X (%08X)", pHwContext->g_id, i++, currentCount, comparator, comparator - previousComparator)); #else #pragma error("Unknown TIMER") #endif } return 1; } The following figure shows how the HPET hardware interrupt via ISR -> IST is translated in a Windows CE Event or Semaphore by the HPET driver. The Event or Semaphore can be used to trigger a Windows CE application. HpetTest.cpp (HpetTest.exe)This cpp file contains sample source how to use the HPET driver from an application. The file is part of a separate (smart device) VS2013 solution. It contains code to measure the generated Event/Semaphore times by means of GetSystemTime() and QueryPerformanceCounter() and QueryPerformanceFrequency() APIs. HPET evaluation If you scan the internet about HPET, you'll find many remarks about buggy HPET implementations and bad performance. Unfortunately that is true. I tested the HPET driver on an Intel ICH7M SBC (release date 2008). When a HPET timer expires on the ICH7M, an interrupt indeed is generated, but right after you clear the interrupt, a few more unwanted interrupts (too soon!) occur as well. I tested and debugged it for a loooong time, but I couldn't get it to work. I concluded ICH7M's HPET is buggy Intel hardware. I tested the HPET driver successfully on a more recent NM10 SBC (release date 2013). With the NM10 chipset however, I am not fully convinced about the timer's frequency accuracy. In the long run - on average - all is fine, but occasionally I experienced upto 20 microseconds delays (which were immediately compensated on the next interrupt). Of course, this was all measured by software, but I still experienced the occasional delay when both the HPET driver IST thread as the application thread ran at CeSetThreadPriority(1). If it is not the hardware, only the kernel can cause this delay. But Windows CE is an RTOS and I have never experienced such long delays with previous versions of Windows CE. I tested and developed this on WCE8, I am not heavily experienced with it yet. Internet forum threads however mention inaccurate HPET timer implementations as well. At this moment I haven't figured out what is going on here. Useful references: http://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/software-developers-hpet-spec-1-0a.pdf http://en.wikipedia.org/wiki/High_Precision_Event_Timer http://wiki.osdev.org/HPET Windows CE BSP source file package for HPET in MyBsp Note that this source code is "As Is". It is still under development and I cannot (and never will) guarantee the correctness of the code. Use it as a guide for your own HPET integration.

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  • TreeMap sort by value

    - by vito huang
    I'm new to java, i want to write an comparator to that will let me sort TreeMap by value instead of the default natural sorting. i tried something like this, but can't find out what went wrong: import java.util.*; class treeMap { public static void main(String[] args) { System.out.println("the main"); byValue cmp = new byValue(); Map<String, Integer> map = new TreeMap<String, Integer>(cmp); map.put("de",10); map.put("ab", 20); map.put("a",5); for (Map.Entry<String,Integer> pair: map.entrySet()) { System.out.println(pair.getKey()+":"+pair.getValue()); } } } class byValue implements Comparator<Map.Entry<String,Integer>> { public int compare(Map.Entry<String,Integer> e1, Map.Entry<String,Integer> e2) { if (e1.getValue() < e2.getValue()){ return 1; } else if (e1.getValue() == e2.getValue()) { return 0; } else { return -1; } } } I guess what am i asking is what controls what get pass to comparator function, can i get an Map.Entry pass to comparator?

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  • MicroChip Sample Code setting Current to a CMPDAC, DAC threshold which expect an voltage

    - by jason hong
    Sorry, the MicroChip Forum is very slow,I prefer to use overflow site to ask questions. dsPIC33FJ06GS101/X02 and dsPIC33FJ16GSX02/X04 device Sample Code // configure comparator2 CMPCON2bits.CMPON = 1; // enable comparator CMPCON2bits.INSEL = 1; // select CMP2B input pin (RB0) CMPCON2bits.RANGE = 1; // select high range, max DAC value = Avdd/2 //CMPDACx: COMPARATOR DAC CONTROL REGISTER //CMREF<9:0>: Comparator Reference Voltage Select bits CMPDAC2 = CURR_HWLIM; // DAC threshold #define CURR_HWLIM 1023 // 1023 // 10.15 * 101A MicroChip Sample code setting CURR_HWLIM which 1023A to COMPDAC2 which expects voltage I think that's mistake.

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  • numeric sort with NSSortDescriptor for NSFetchedResultsController

    - by edziubudzik
    I'm trying to numerically sort data that's displayed in a UITableView. Before that I used such a sort descriptor: sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(caseInsensitiveCompare:)]; now I'd like to use block to sort this numerically like this: sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES comparator:^NSComparisonResult(id obj1, id obj2) { return [((NSString *)obj1) compare:(NSString *)obj2 options:NSCaseInsensitiveSearch | NSNumericSearch]; }]; but it sorts the data incorectly causing conflict with section names in NSFetchedResultsController. So I tryed to immitate the old sorting with a comparator block - just to be sure that the problem is not caused by numeric comparison. The problem is that those lines: sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES comparator:^NSComparisonResult(id obj1, id obj2) { return [((NSString *)obj1) caseInsensitiveCompare:(NSString *)obj2]; }]; also cause the same error and I don't see why they won't sort the data in the same way the first method did... Any ideas?

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  • Sorting and Filtering By Model-Based LOV Display Value

    - by Steven Davelaar
    If you use a model-based LOV and you use display type "choice", then ADF nicely displays the display value, even if the table is read-only. In the screen shot below, you see the RegionName attribute displayed instead of the RegionId. This is accomplished by the model-based LOV, I did not modify the Countries view object to include a join with Regions.  Also note the sort icon, the table is sorted by RegionId. This sorting typically results in a bug reported by your test team. Europe really shouldn't come before America when sorting ascending, right? To fix this, we could of course change the Countries view object query and add a join with the Regions table to include the RegionName attribute. If the table is updateable, we still need the choice list, so we need to move the model-based LOV from the RegionId attribute to the RegionName attribute and hide the RegionId attribute in the table. But that is a lot of work for such a simple requirement, in particular if we have lots of model-based choice lists in our view object. Fortunately, there is an easier way to do this, with some generic code in your view object base class that fixes this at once for all model-based choice lists that we have defined in our application. The trick is to override the method getSortCriteria() in the base view object class. By default, this method returns null because the sorting is done in the database through a SQL Order By clause. However, if the getSortCriteria method does return a sort criteria the framework will perform in memory sorting which is what we need to achieve sorting by region name. So, inside this method we need to evaluate the Order By clause, and if the order by column matches an attribute that has a model-based LOV choicelist defined with a display attribute that is different from the value attribute, we need to return a sort criterria. Here is the complete code of this method: public SortCriteria[] getSortCriteria() {   String orderBy = getOrderByClause();          if (orderBy!=null )   {     boolean descending = false;     if (orderBy.endsWith(" DESC"))      {       descending = true;       orderBy = orderBy.substring(0,orderBy.length()-5);     }     // extract column name, is part after the dot     int dotpos = orderBy.lastIndexOf(".");     String columnName = orderBy.substring(dotpos+1);     // loop over attributes and find matching attribute     AttributeDef orderByAttrDef = null;     for (AttributeDef attrDef : getAttributeDefs())     {       if (columnName.equals(attrDef.getColumnName()))       {         orderByAttrDef = attrDef;         break;       }     }     if (orderByAttrDef!=null && "choice".equals(orderByAttrDef.getProperty("CONTROLTYPE"))          && orderByAttrDef.getListBindingDef()!=null)     {       String orderbyAttr = orderByAttrDef.getName();       String[] displayAttrs = orderByAttrDef.getListBindingDef().getListDisplayAttrNames();       String[] listAttrs = orderByAttrDef.getListBindingDef().getListAttrNames();       // if first list display attributes is not the same as first list attribute, than the value       // displayed is different from the value copied back to the order by attribute, in which case we need to       // use our custom comparator       if (displayAttrs!=null && listAttrs!=null && displayAttrs.length>0 && !displayAttrs[0].equals(listAttrs[0]))       {                  SortCriteriaImpl sc1 = new SortCriteriaImpl(orderbyAttr, descending);         SortCriteria[] sc = new SortCriteriaImpl[]{sc1};         return sc;                           }     }     }   return super.getSortCriteria(); } If this method returns a sort criteria, then the framework will call the sort method on the view object. The sort method uses a Comparator object to determine the sequence in which the rows should be returned. This comparator is retrieved by calling the getRowComparator method on the view object. So, to ensure sorting by our display value, we need to override this method to return our custom comparator: public Comparator getRowComparator() {   return new LovDisplayAttributeRowComparator(getSortCriteria()); } The custom comparator class extends the default RowComparator class and overrides the method compareRows and looks up the choice display value to compare the two rows. The complete code of this class is included in the sample application.  With this code in place, clicking on the Region sort icon nicely sorts the countries by RegionName, as you can see below. When using the Query-By-Example table filter at the top of the table, you typically want to use the same choice list to filter the rows. One way to do that is documented in ADF code corner sample 16 - How To Customize the ADF Faces Table Filter.The solution in this sample is perfectly fine to use. This sample requires you to define a separate iterator binding and associated tree binding to populate the choice list in the table filter area using the af:iterator tag. You might be able to reuse the same LOV view object instance in this iterator binding that is used as view accessor for the model-bassed LOV. However, I have seen quite a few customers who have a generic LOV view object (mapped to one "refcodes" table) with the bind variable values set in the LOV view accessor. In such a scenario, some duplicate work is needed to get a dedicated view object instance with the correct bind variables that can be used in the iterator binding. Looking for ways to maximize reuse, wouldn't it be nice if we could just reuse our model-based LOV to populate this filter choice list? Well we can. Here are the basic steps: 1. Create an attribute list binding in the page definition that we can use to retrieve the list of SelectItems needed to populate the choice list <list StaticList="false" Uses="LOV_RegionId"               IterBinding="CountriesView1Iterator" id="RegionId"/>  We need this "current row" list binding because the implicit list binding used by the item in the table is not accessible outside a table row, we cannot use the expression #{row.bindings.RegionId} in the table filter facet. 2. Create a Map-style managed bean with the get method retrieving the list binding as key, and returning the list of SelectItems. To return this list, we take the list of selectItems contained by the list binding and replace the index number that is normally used as key value with the actual attribute value that is set by the choice list. Here is the code of the get method:  public Object get(Object key) {   if (key instanceof FacesCtrlListBinding)   {     // we need to cast to internal class FacesCtrlListBinding rather than JUCtrlListBinding to     // be able to call getItems method. To prevent this import, we could evaluate an EL expression     // to get the list of items     FacesCtrlListBinding lb = (FacesCtrlListBinding) key;     if (cachedFilterLists.containsKey(lb.getName()))     {       return cachedFilterLists.get(lb.getName());     }     List<SelectItem> items = (List<SelectItem>)lb.getItems();     if (items==null || items.size()==0)     {       return items;     }     List<SelectItem> newItems = new ArrayList<SelectItem>();     JUCtrlValueDef def = ((JUCtrlValueDef)lb.getDef());     String valueAttr = def.getFirstAttrName();     // the items list has an index number as value, we need to replace this with the actual     // value of the attribute that is copied back by the choice list     for (int i = 0; i < items.size(); i++)     {       SelectItem si = (SelectItem) items.get(i);       Object value = lb.getValueFromList(i);       if (value instanceof Row)       {         Row row = (Row) value;         si.setValue(row.getAttribute(valueAttr));                 }       else       {         // this is the "empty" row, set value to empty string so all rows will be returned         // as user no longer wants to filter on this attribute         si.setValue("");       }       newItems.add(si);     }     cachedFilterLists.put(lb.getName(), newItems);     return newItems;   }   return null; } Note that we added caching to speed up performance, and to handle the situation where table filters or search criteria are set such that no rows are retrieved in the table. When there are no rows, there is no current row and the getItems method on the list binding will return no items.  An alternative approach to create the list of SelectItems would be to retrieve the iterator binding from the list binding and loop over the rows in the iterator binding rowset. Then we wouldn't need the import of the ADF internal oracle.adfinternal.view.faces.model.binding.FacesCtrlListBinding class, but then we need to figure out the display attributes from the list binding definition, and possible separate them with a dash if multiple display attributes are defined in the LOV. Doable but less reuse and more work. 3. Inside the filter facet for the column create an af:selectOneChoice with the value property of the f:selectItems tag referencing the get method of the managed bean:  <f:facet name="filter">   <af:selectOneChoice id="soc0" autoSubmit="true"                       value="#{vs.filterCriteria.RegionId}">     <!-- attention: the RegionId list binding must be created manually in the page definition! -->                       <f:selectItems id="si0"                    value="#{viewScope.TableFilterChoiceList[bindings.RegionId]}"/>   </af:selectOneChoice> </f:facet> Note that the managed bean is defined in viewScope for the caching to take effect. Here is a screen shot of the tabe filter in action: You can download the sample application here. 

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  • Why is my List.Sort method in C# reversing the order of my list?

    - by Fiona Holder
    I have a list of items in a generic list: A1 (sort index 1) A2 (sort index 2) B1 (sort index 3) B2 (sort index 3) B3 (sort index 3) The comparator on them takes the form: this.sortIndex.CompareTo(other.sortIndex) When I do a List.Sort() on the list of items, I get the following order out: A1 A2 B3 B2 B1 It has obviously worked in the sense that the sort indexes are in the right order, but I really don't want it to be re-ordering the 'B' items. Is there any tweak I can make to my comparator to fix this?

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  • Sort a list of pointers.

    - by YuppieNetworking
    Hello all, Once again I find myself failing at some really simple task in C++. Sometimes I wish I could de-learn all I know from OO in java, since my problems usually start by thinking like Java. Anyways, I have a std::list<BaseObject*> that I want to sort. Let's say that BaseObject is: class BaseObject { protected: int id; public: BaseObject(int i) : id(i) {}; virtual ~BaseObject() {}; }; I can sort the list of pointer to BaseObject with a comparator struct: struct Comparator { bool operator()(const BaseObject* o1, const BaseObject* o2) const { return o1->id < o2->id; } }; And it would look like this: std::list<BaseObject*> mylist; mylist.push_back(new BaseObject(1)); mylist.push_back(new BaseObject(2)); // ... mylist.sort(Comparator()); // intentionally omitted deletes and exception handling Until here, everything is a-ok. However, I introduced some derived classes: class Child : public BaseObject { protected: int var; public: Child(int id1, int n) : BaseObject(id1), var(n) {}; virtual ~Child() {}; }; class GrandChild : public Child { public: GrandChild(int id1, int n) : Child(id1,n) {}; virtual ~GrandChild() {}; }; So now I would like to sort following the following rules: For any Child object c and BaseObject b, b<c To compare BaseObject objects, use its ids, as before. To compare Child objects, compare its vars. If they are equal, fallback to rule 2. GrandChild objects should fallback to the Child behavior (rule 3). I initially thought that I could probably do some casts in Comparator. However, this casts away constness. Then I thought that probably I could compare typeids, but then everything looked messy and it is not even correct. How could I implement this sort, still using list<BaseObject*>::sort ? Thank you

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  • How to sort & Group in Android?

    - by crickpatel0024
    I have ArrayList and I want to sort and group all data by header in Android. How it is possible in Android? please help me.below me from owner And set header Me And Joe Manager From owner And set Header in listview. How to do that in Android? My code in below:: public class Request extends Activity { private String assosiatetoken; private ArrayList<All_Request_data_dto> list = new ArrayList<All_Request_data_dto>(); ListView lv; Button back; private Spinner spndata; String[] reqspinner = { "Request Date", "Last Update", "Type", "Owner", "State" }; ArrayAdapter<String> adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.request); assosiatetoken = MyApplication.getToken(); new doinbackground(this).execute(); back = (Button) findViewById(R.id.button1); spndata = (Spinner) findViewById(R.id.list_all_quize_req); adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, reqspinner); spndata.setAdapter(adapter); lv = (ListView) findViewById(R.id.listrequestdata); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> a, View v, int position, long id) { Intent edit = new Intent(Request.this, Request_webview.class); // edit.putExtra("Cat_url", url_link); startActivity(edit); } }); spndata.setOnItemSelectedListener(new OnItemSelectedListener() { public void onItemSelected(AdapterView<?> arg0, View arg1, int position, long arg3) { switch (position) { case 0: list = DBAdpter.requestUserData(assosiatetoken); Collections.sort(list, byDate1); // Collections.reverse(list); for (int i = 0; i < list.size(); i++) { if (list.get(i).submitDate != null) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } } break; case 1: list = DBAdpter.requestUserData(assosiatetoken); Collections.sort(list, byDate); for (int i = 0; i < list.size(); i++) { if (list.get(i).lastModifiedDate != null) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } } break; case 2: list = DBAdpter.requestUserData(assosiatetoken); Collections.sort(list, byDate3); // Collections.reverse(list); for (int i = 0; i < list.size(); i++) { if (list.get(i).state != null) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } } break; case 3: list = DBAdpter.requestUserData(assosiatetoken); for (int i = 0; i < list.size(); i++) { lv.setAdapter(new MyListAdapter( getApplicationContext(), list)); } break; default: break; } } public void onNothingSelected(AdapterView<?> arg0) { } }); back.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { finish(); } }); } static final Comparator<All_Request_data_dto> byDate = new Comparator<All_Request_data_dto>() { SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy hh:mm:ss a"); public int compare(All_Request_data_dto ord1, All_Request_data_dto ord2) { java.util.Date d1 = null; java.util.Date d2 = null; try { d1 = sdf.parse(ord1.lastModifiedDate); d2 = sdf.parse(ord2.lastModifiedDate); } catch (java.text.ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } return (d1.getTime() > d2.getTime() ? -1 : 1); // descending // return (d1.getTime() > d2.getTime() ? 1 : -1); //ascending } }; static final Comparator<All_Request_data_dto> byDate1 = new Comparator<All_Request_data_dto>() { SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy hh:mm:ss a"); public int compare(All_Request_data_dto ord1, All_Request_data_dto ord2) { java.util.Date d1 = null; java.util.Date d2 = null; try { d1 = sdf.parse(ord1.submitDate); d2 = sdf.parse(ord2.submitDate); } catch (java.text.ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } return (d1.getTime() > d2.getTime() ? -1 : 1); // descending // return (d1.getTime() > d2.getTime() ? 1 : -1); //ascending } }; static final Comparator<All_Request_data_dto> byDate3 = new Comparator<All_Request_data_dto>() { public int compare(All_Request_data_dto ord1, All_Request_data_dto ord2) { String d1 = null; String d2 = null; d1 = ord1.state; d2 = ord2.state; return d1.compareToIgnoreCase(d2); } }; class doinbackground extends AsyncTask<Void, Void, Void> { ProgressDialog pd; private Context ctx; public doinbackground(Context c) { ctx = c; } @Override protected void onPreExecute() { super.onPreExecute(); pd = new ProgressDialog(ctx); pd.setMessage("Loading..."); pd.show(); } @Override protected Void doInBackground(Void... Params) { return null; } @Override protected void onPostExecute(Void result) { super.onPostExecute(result); pd.cancel(); } } public class MyListAdapter extends BaseAdapter { private ArrayList<All_Request_data_dto> list; public MyListAdapter(Context mContext, ArrayList<All_Request_data_dto> list) { this.list = list; } public int getCount() { return list.size(); } public All_Request_data_dto getItem(int position) { return list.get(position); } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { // if (convertView == null) { LayoutInflater inflator = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE); convertView = inflator.inflate(R.layout.custom_request_data, null); TextView req_id = (TextView) convertView.findViewById(R.id.req_txt); TextView date = (TextView) convertView.findViewById(R.id.date_txt); TextView owner = (TextView) convertView .findViewById(R.id.owner_txt); TextView state = (TextView) convertView .findViewById(R.id.state_txt); req_id.setText(list.get(position).requestId + " - " + list.get(position).title); date.setText(list.get(position).lastModifiedDate + " - " + list.get(position).submitDate); owner.setText(list.get(position).owner); state.setText(list.get(position).state); // } return convertView; } } }

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  • Try a sample: Using the counter predicate for event sampling

    - by extended_events
    Extended Events offers a rich filtering mechanism, called predicates, that allows you to reduce the number of events you collect by specifying criteria that will be applied during event collection. (You can find more information about predicates in Using SQL Server 2008 Extended Events (by Jonathan Kehayias)) By evaluating predicates early in the event firing sequence we can reduce the performance impact of collecting events by stopping event collection when the criteria are not met. You can specify predicates on both event fields and on a special object called a predicate source. Predicate sources are similar to action in that they typically are related to some type of global information available from the server. You will find that many of the actions available in Extended Events have equivalent predicate sources, but actions and predicates sources are not the same thing. Applying predicates, whether on a field or predicate source, is very similar to what you are used to in T-SQL in terms of how they work; you pick some field/source and compare it to a value, for example, session_id = 52. There is one predicate source that merits special attention though, not just for its special use, but for how the order of predicate evaluation impacts the behavior you see. I’m referring to the counter predicate source. The counter predicate source gives you a way to sample a subset of events that otherwise meet the criteria of the predicate; for example you could collect every other event, or only every tenth event. Simple CountingThe counter predicate source works by creating an in memory counter that increments every time the predicate statement is evaluated. Here is a simple example with my favorite event, sql_statement_completed, that only collects the second statement that is run. (OK, that’s not much of a sample, but this is for demonstration purposes. Here is the session definition: CREATE EVENT SESSION counter_test ON SERVERADD EVENT sqlserver.sql_statement_completed    (ACTION (sqlserver.sql_text)    WHERE package0.counter = 2)ADD TARGET package0.ring_bufferWITH (MAX_DISPATCH_LATENCY = 1 SECONDS) You can find general information about the session DDL syntax in BOL and from Pedro’s post Introduction to Extended Events. The important part here is the WHERE statement that defines that I only what the event where package0.count = 2; in other words, only the second instance of the event. Notice that I need to provide the package name along with the predicate source. You don’t need to provide the package name if you’re using event fields, only for predicate sources. Let’s say I run the following test queries: -- Run three statements to test the sessionSELECT 'This is the first statement'GOSELECT 'This is the second statement'GOSELECT 'This is the third statement';GO Once you return the event data from the ring buffer and parse the XML (see my earlier post on reading event data) you should see something like this: event_name sql_text sql_statement_completed SELECT ‘This is the second statement’ You can see that only the second statement from the test was actually collected. (Feel free to try this yourself. Check out what happens if you remove the WHERE statement from your session. Go ahead, I’ll wait.) Percentage Sampling OK, so that wasn’t particularly interesting, but you can probably see that this could be interesting, for example, lets say I need a 25% sample of the statements executed on my server for some type of QA analysis, that might be more interesting than just the second statement. All comparisons of predicates are handled using an object called a predicate comparator; the simple comparisons such as equals, greater than, etc. are mapped to the common mathematical symbols you know and love (eg. = and >), but to do the less common comparisons you will need to use the predicate comparators directly. You would probably look to the MOD operation to do this type sampling; we would too, but we don’t call it MOD, we call it divides_by_uint64. This comparator evaluates whether one number is divisible by another with no remainder. The general syntax for using a predicate comparator is pred_comp(field, value), field is always first and value is always second. So lets take a look at how the session changes to answer our new question of 25% sampling: CREATE EVENT SESSION counter_test_25 ON SERVERADD EVENT sqlserver.sql_statement_completed    (ACTION (sqlserver.sql_text)    WHERE package0.divides_by_uint64(package0.counter,4))ADD TARGET package0.ring_bufferWITH (MAX_DISPATCH_LATENCY = 1 SECONDS)GO Here I’ve replaced the simple equivalency check with the divides_by_uint64 comparator to check if the counter is evenly divisible by 4, which gives us back every fourth record. I’ll leave it as an exercise for the reader to test this session. Why order matters I indicated at the start of this post that order matters when it comes to the counter predicate – it does. Like most other predicate systems, Extended Events evaluates the predicate statement from left to right; as soon as the predicate statement is proven false we abandon evaluation of the remainder of the statement. The counter predicate source is only incremented when it is evaluated so whether or not the counter is incremented will depend on where it is in the predicate statement and whether a previous criteria made the predicate false or not. Here is a generic example: Pred1: (WHERE statement_1 AND package0.counter = 2)Pred2: (WHERE package0.counter = 2 AND statement_1) Let’s say I cause a number of events as follows and examine what happens to the counter predicate source. Iteration Statement Pred1 Counter Pred2 Counter A Not statement_1 0 1 B statement_1 1 2 C Not statement_1 1 3 D statement_1 2 4 As you can see, in the case of Pred1, statement_1 is evaluated first, when it fails (A & C) predicate evaluation is stopped and the counter is not incremented. With Pred2 the counter is evaluated first, so it is incremented on every iteration of the event and the remaining parts of the predicate are then evaluated. In this example, Pred1 would return an event for D while Pred2 would return an event for B. But wait, there is an interesting side-effect here; consider Pred2 if I had run my statements in the following order: Not statement_1 Not statement_1 statement_1 statement_1 In this case I would never get an event back from the system because the point at which counter=2, the rest of the predicate evaluates as false so the event is not returned. If you’re using the counter target for sampling and you’re not getting the expected events, or any events, check the order of the predicate criteria. As a general rule I’d suggest that the counter criteria should be the last element of your predicate statement since that will assure that your sampling rate will apply to the set of event records defined by the rest of your predicate. Aside: I’m interested in hearing about uses for putting the counter predicate criteria earlier in the predicate statement. If you have one, post it in a comment to share with the class. - Mike Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Why does the Java Collections Framework offer two different ways to sort?

    - by dvanaria
    If I have a list of elements I would like to sort, Java offers two ways to go about this. For example, lets say I have a list of Movie objects and I’d like to sort them by title. One way I could do this is by calling the one-argument version of the static java.util.Collections.sort( ) method with my movie list as the single argument. So I would call Collections.sort(myMovieList). In order for this to work, the Movie class would have to be declared to implement the java.lang.Comparable interface, and the required method compareTo( ) would have to be implemented inside this class. Another way to sort is by calling the two-argument version of the static java.util.Collections.sort( ) method with the movie list and a java.util.Comparator object as it’s arguments. I would call Collections.sort(myMovieList, titleComparator). In this case, the Movie class wouldn’t implement the Comparable interface. Instead, inside the main class that builds and maintains the movie list itself, I would create an inner class that implements the java.util.Comparator interface, and implement the one required method compare( ). Then I'd create an instance of this class and call the two-argument version of sort( ). The benefit of this second method is you can create an unlimited number of these inner class Comparators, so you can sort a list of objects in different ways. In the example above, you could have another Comparator to sort by the year a movie was made, for example. My question is, why bother to learn both ways to sort in Java, when the two-argument version of Collections.sort( ) does everything the first one-argument version does, but with the added benefit of being able to sort the list’s elements based on several different criteria? It would be one less thing to have to keep in your mind while coding. You’d have one basic mechanism of sorting lists in Java to know.

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  • "no inclosing instance error " while getting top term frequencies for document from Lucene index

    - by Julia
    Hello ! I am trying to get the most occurring term frequencies for every particular document in Lucene index. I am trying to set the treshold of top occuring terms that I care about, maybe 20 However, I am getting the "no inclosing instance of type DisplayTermVectors is accessible" when calling Comparator... So to this function I pass vector of every document and max top terms i would like to know protected static Collection getTopTerms(TermFreqVector tfv, int maxTerms){ String[] terms = tfv.getTerms(); int[] tFreqs = tfv.getTermFrequencies(); List result = new ArrayList(terms.length); for (int i = 0; i < tFreqs.length; i++) { TermFrq tf = new TermFrq(terms[i], tFreqs[i]); result.add(tf); } Collections.sort(result, new FreqComparator()); if(maxTerms < result.size()){ result = result.subList(0, maxTerms); } return result; } /Class for objects to hold the term/freq pairs/ static class TermFrq{ private String term; private int freq; public TermFrq(String term,int freq){ this.term = term; this.freq = freq; } public String getTerm(){ return this.term; } public int getFreq(){ return this.freq; } } /*Comparator to compare the objects by the frequency*/ class FreqComparator implements Comparator{ public int compare(Object pair1, Object pair2){ int f1 = ((TermFrq)pair1).getFreq(); int f2 = ((TermFrq)pair2).getFreq(); if(f1 > f2) return 1; else if(f1 < f2) return -1; else return 0; } } Explanations and corrections i will very much appreciate, and also if someone else had experience with term frequency extraction and did it better way, I am opened to all suggestions! Please help!!!! Thanx!

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  • Using a priority queue in Java

    - by Bharat
    Forgive me if this is a tried question, but I'm having a little difficulty figuring it out. I currently have a class Node, and each 'node' is a square in a maze. I'm trying to implement the A* algorithm, so each of these nodes will have an f-cost (int) data member inside of it. I was wondering if there's a way that I can create a priority queue of these nodes, and set up the f-cost variable as the comparator? I've looked at examples online, but all I can find are String priority queues. Can I implement Comparator for the Node class? Would this allow me to access the data member stored inside it? Many Thanks!

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  • How can I make the C# compiler infer these type parameters automatically?

    - by John Feminella
    I have some code that looks like the following. First I have some domain classes and some special comparators for them. public class Fruit { public int Calories { get; set; } public string Name { get; set; } } public class FruitEqualityComparer : IEqualityComparer<Fruit> { // ... } public class BasketEqualityComparer : IEqualityComparer<IEnumerable<Fruit>> { // ... } Next, I have a helper class called ConstraintChecker. It has a simple BaseEquals method that makes sure some simple base cases are considered: public static class ConstraintChecker { public static bool BaseEquals(T lhs, T rhs) { bool sameObject = l == r; bool leftNull = l == null; bool rightNull = r == null; return sameObject && !leftNull && !rightNull; } There's also a SemanticEquals method which is just a BaseEquals check and a comparator function that you specify. public static bool SemanticEquals<T>(T lhs, T rhs, Func<T, T, bool> f) { return BaseEquals(lhs, rhs) && f(lhs, rhs); } And finally there's a SemanticSequenceEquals method which accepts two IEnumerable<T> instances to compare, and an IEqualityComparer instance that will get called on each pair of elements in the list via Enumerable.SequenceEquals. public static bool SemanticSequenceEquals<T, U, V>(U lhs, U rhs, V comparator) where U : IEnumerable<T> where V : IEqualityComparer<T> { return SemanticEquals(lhs, rhs, (l, r) => lhs.SequenceEqual(rhs, comparator)); } } // end of ConstraintChecker The point of SemanticSequenceEquals is that you don't have to define two comparators whenever you want to compare both IEnumerable<T> and T instances; now you can just specify an IEqualityComparer<T> and it will also handle lists when you invoke SemanticSequenceEquals. So I could get rid of the BasketEqualityComparer class, which would be nice. But there's a problem. The C# compiler can't figure out the types involved when you invoke SemanticSequenceEquals: return ConstraintChecker.SemanticSequenceEquals(lhs, rhs, new FruitEqualityComparer()); If I specify them explicitly, it works: return ConstraintChecker.SemanticSequenceEquals< Fruit, IEnumerable<Fruit>, IEqualityComparer<Fruit> > (lhs, rhs, new FruitEqualityComparer()); What can I change here so that I don't have to write the type parameters explicitly?

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