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Search found 547 results on 22 pages for 'hashmap'.

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  • sorting in python

    - by tipu
    I have a hashmap like so: results[tweet_id] = {"score" : float(dot(query,doc) / (norm(query) * norm(doc))), "tweet" : tweet} What I'd like to do is to sort results by the innser "score" key. I don't know how possible this is, I saw many sorting tutorials but they were for simple (not nested) data structures.

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  • java concurrency: many writers, one reader

    - by Janning
    I need to gather some statistics in my software and i am trying to make it fast and correct, which is not easy (for me!) first my code so far with two classes, a StatsService and a StatsHarvester public class StatsService { private Map<String, Long> stats = new HashMap<String, Long>(1000); public void notify ( String key ) { Long value = 1l; synchronized (stats) { if (stats.containsKey(key)) { value = stats.get(key) + 1; } stats.put(key, value); } } public Map<String, Long> getStats ( ) { Map<String, Long> copy; synchronized (stats) { copy = new HashMap<String, Long>(stats); stats.clear(); } return copy; } } this is my second class, a harvester which collects the stats from time to time and writes them to a database. public class StatsHarvester implements Runnable { private StatsService statsService; private Thread t; public void init ( ) { t = new Thread(this); t.start(); } public synchronized void run ( ) { while (true) { try { wait(5 * 60 * 1000); // 5 minutes collectAndSave(); } catch (InterruptedException e) { e.printStackTrace(); } } } private void collectAndSave ( ) { Map<String, Long> stats = statsService.getStats(); // do something like: // saveRecords(stats); } } At runtime it will have about 30 concurrent running threads each calling notify(key) about 100 times. Only one StatsHarvester is calling statsService.getStats() So i have many writers and only one reader. it would be nice to have accurate stats but i don't care if some records are lost on high concurrency. The reader should run every 5 Minutes or whatever is reasonable. Writing should be as fast as possible. Reading should be fast but if it locks for about 300ms every 5 minutes, its fine. I've read many docs (Java concurrency in practice, effective java and so on), but i have the strong feeling that i need your advice to get it right. I hope i stated my problem clear and short enough to get valuable help.

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  • Converting back from toString to Object

    - by MontyBongo
    Is there any way to covert from toString back to the object in Java? For example: Map<String, String> myMap = new HashMap<String, String>(); myMap.put("value1", "test1"); myMap.put("value2", "test2"); String str = myMap.toString(); Is there any way to convert this String back to the Map?

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  • Changing backgroundcolor in listview (expandable listview)

    - by Stofke
    I'm trying to dynamically change a backgroundcolor in a part of a listview, I have on example that works fine in a listview when I try to replicate it in another part with an expandable listview it fails This piece of code works and displays a different color if a student is online or not ... map.put(KEY_FIRSTNAME, temp.firstName); map.put(KEY_NAME, temp.name); map.put(KEY_EMAIL, temp.email); map.put(KEY_ISONLINE, temp.isOnLine); // change image if student is online or not Log.d("demo", "is on line= " + temp.isOnLine); if (temp.isOnLine.equalsIgnoreCase("1")) { map.put(KEY_IMAGE_ISONLINE, R.color.greenColor); } else { map.put(KEY_IMAGE_ISONLINE, R.color.greyColor); } listItem.add(map); } myListView = (ListView) findViewById(R.id.listViewTabLeerlingen); SimpleAdapter adapter = new SimpleAdapter(StudentTab.this, listItem, R.layout.list_item_student, new String[] { KEY_FIRSTNAME, KEY_NAME, KEY_IMAGE_ISONLINE }, new int[] { R.id.firstNameTextView, R.id.lastNameTextView, R.id.logo }); myListView.setAdapter(adapter); the xml that goes along with it <ImageView android:id="@+id/logo" android:layout_width="85dp" android:layout_height="match_parent" android:background="@color/greenColor" android:contentDescription="Image if student is online or not" android:src="@drawable/transparent_pixel" /> The above works fine however the following code (just part of the code) ... ArrayList<Map<String, Object>> children = new ArrayList<Map<String, Object>>(); for (int i = 0; i < _data.length(); i++) { try { JSONArray tmp = _data.getJSONArray(i); HashMap<String, Object> map = new HashMap<String, Object>(); // change image if student is online or not if (tmp.getString(3).equalsIgnoreCase("0")) { map.put(KEY_POINTS,R.color.redColor); }else{ map.put(KEY_POINTS,R.color.greenColor); } map.put(KEY_QUESTIONTEXT, tmp.getString(1)); map.put(KEY_ANSWER, tmp.getString(2)); children.add(map); } catch (JSONException e) { e.printStackTrace(); } childData.add(children); ... ... ArrayList<ArrayList<Map<String, Object>>> childData) { SimpleExpandableListAdapter listAdapter = new SimpleExpandableListAdapter( this, groupData, R.layout.list_item_results_students, new String[] { KEY_FIRSTNAME, KEY_NAME, KEY_ISJUIST }, new int[] { R.id.firstnameResults, R.id.nameResults, R.id.resultsTextView }, childData, R.layout.list_item_results_results, new String[] { KEY_QUESTIONTEXT, KEY_ANSWER, KEY_POINTS }, new int[] { R.id.questionTextView, R.id.answerTextTextView, R.id.score }); ExpandableListView myListView = (ExpandableListView) findViewById(R.id.listViewTabResultaten); myListView.setAdapter(listAdapter); with xml: <ImageView android:id="@+id/score" android:layout_width="16dp" android:layout_height="match_parent" android:background="@color/greenColor" android:contentDescription="Image if student has correct answer" android:src="@drawable/transparent_pixel" /> I will get this error: 06-09 10:35:21.490: E/AndroidRuntime(4406): java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.TextView

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  • Java Data Structure

    - by Joe
    Hi there, I'm looking for a data structure that will act like a Queue so that I can hava First In First Out behaviour, but ideally I would also be able to see if an element exists in that Queue in constant time as you can do with a HashMap, rather than the linear time that you get with a LinkedList. I thought a LinkedHashMap might do the job, but although I could make an iterator and just take and then remove the first element of the iteration to produce a sort of poll() method, I'm wondering if there is a better way. Many thanks in advance

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  • Any big difference between using contains or loop through a list?

    - by Nazgulled
    Hi, Performance wise, is there really a big difference between using: ArrayList.contains(o) vs foreach|iterator LinkedList.contains(o) vs foreach|iterator HashMap.(containsKey|containsValue) vs foreach|iterator TreeMap.(containsKey|containsValue) vs foreach|iterator Of course, for the foreach|iterator loops, I'll have to explicitly compare the methods and return true or false accordingly. The object I'm comparing is an object where equals() and hashcode() are both properly overridden.

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  • BufferedReader no longer buffering after a while?

    - by BobTurbo
    Sorry I can't post code but I have a bufferedreader with 50000000 bytes set as the buffer size. It works as you would expect for half an hour, the HDD light flashing every two minutes or so, reading in the big chunk of data, and then going quiet again as the CPU processes it. But after about half an hour (this is a very big file), the HDD starts thrashing as if it is reading one byte at a time. It is still in the same loop and I think I checked free ram to rule out swapping (heap size is default). Probably won't get any helpful answers, but worth a try. OK I have changed heap size to 768mb and still nothing. There is plenty of free memory and java.exe is only using about 300mb. Now I have profiled it and heap stays at about 200MB, well below what is available. CPU stays at 50%. Yet the HDD starts thrashing like crazy. I have.. no idea. I am going to rewrite the whole thing in c#, that is my solution. Here is the code (it is just a throw-away script, not pretty): BufferedReader s = null; HashMap<String, Integer> allWords = new HashMap<String, Integer>(); HashSet<String> pageWords = new HashSet<String>(); long[] pageCount = new long[78592]; long pages = 0; Scanner wordFile = new Scanner(new BufferedReader(new FileReader("allWords.txt"))); while (wordFile.hasNext()) { allWords.put(wordFile.next(), Integer.parseInt(wordFile.next())); } s = new BufferedReader(new FileReader("wikipedia/enwiki-latest-pages-articles.xml"), 50000000); StringBuilder words = new StringBuilder(); String nextLine = null; while ((nextLine = s.readLine()) != null) { if (a.matcher(nextLine).matches()) { continue; } else if (b.matcher(nextLine).matches()) { continue; } else if (c.matcher(nextLine).matches()) { continue; } else if (d.matcher(nextLine).matches()) { nextLine = s.readLine(); if (e.matcher(nextLine).matches()) { if (f.matcher(s.readLine()).matches()) { pageWords.addAll(Arrays.asList(words.toString().toLowerCase().split("[^a-zA-Z]"))); words.setLength(0); pages++; for (String word : pageWords) { if (allWords.containsKey(word)) { pageCount[allWords.get(word)]++; } else if (!word.isEmpty() && allWords.containsKey(word.substring(0, word.length() - 1))) { pageCount[allWords.get(word.substring(0, word.length() - 1))]++; } } pageWords.clear(); } } } else if (g.matcher(nextLine).matches()) { continue; } words.append(nextLine); words.append(" "); }

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  • Difference between a Deprecated and Legacy API?

    - by Vaibhav Bajpai
    I was studying the legacy API's in the Java's Collection Framework and I learnt that classes such as Vector and HashTable have been superseded by ArrayList and HashMap. However still they are NOT deprecated, and deemed as legacy when essentially, deprecation is applied to software features that are superseded and should be avoided, so, I am not sure when is a API deemed legacy and when it is deprecated.

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  • Help using recursion in Java

    - by Mercer
    I have a class Group. In the class I have two fields, idGroup IdGroupGroup. Groups may be part of other groups. My class Group is defined in a HashMap<Integer,Integer>; the key is IdGroupGroup and value is idGroup. I want to search the map for a particular idGroup; can I use recursion to do this?

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  • Creating a simple java hash server

    - by Blankman
    Is it possible to create a simple server in Java that returns a response based on a given key? So it would be a simple program, that stores a hashmap and returns the result based on a key provided by the client. What would be the fasted implementation, to have it over HTTP or a socket? The client will be a web based application.

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  • Communicate progress from local Service

    - by kpdvx
    An application I'm building uses a local Service for downloading files from the web to the phone's SD card. In this app users can browse lists of books, and read them while online. A user can also download a pdf copy of a book for offline viewing. To handle downloads I'm using a locally bound Service. I do not want this Service to run all the time, only when downloading files. So that the Service can shut itself down when its tasks are complete, I am not binding to the service, rather I'm sending an "enqueue for download" command through the Intent passed to Context.startService. Books available for download are shown in a list. A user can choose to download a book by clicking on its row in the list. On download, I need to show download progress using a ProgressBar on the actual book list row. I need to also show, on the rows, if a book is enqueued for download, or if its download has completed or failed. The books can be shown in different activities throughout the application--in search, or in the user's list of favorite books, for example. When the books are shown in different places, these are not the same objects, but they are uniquely identified by their bookId. Because I do not want to bind to the service from every Activity, my tentative plan was to use a public static final HashMap on the Service class itself to contain a mapping of bookId to download status, an enum of enqueued, downloading, cancelled, etc. Each book view, when displayed, would check this static HashMap, and if the bookId is in the map, retrieve and display its status. I don't particularly like this idea, but at the moment it's the only way I can think of to retrieve status from the Service without having to bind to it and start it. Additionally I need to retrieve download progress percent from the Service, for a given bookId, if it is the active download. Again I'd rather not bind to the service from every activity, so I'm not sure how to go about retrieving current progress from the Service. My current plan is to use some sort of singleton mediator, that the Service will push updates to, and the views can read from. But I'm not terribly happy with this idea. The reason I'd like to avoid binding to the Service from each Activity is 1.) I'm already running another Service and 2.) binding is verbose and I'd like to avoid needing to pass around a reference to the Service (but admittedly this isn't too much of a problem). Perhaps binding to the local Service isn't expensive enough to warrant this other setup? Should I not be concerned about binding to it from each Activity? Maybe this is a non-issue?

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  • I want to read a big text file

    - by Rozer
    I want to read a big text file, what i decided to create four threads and read 25% of file by each one. and then join them. but its not more impressive. can any one tell me can i use concurrent programming for the same. as my file structure have some data as name contact compnay policyname policynumber uniqueno and I want to put all data in hashmap at last. thanks

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  • Runtime casting from String to other datatype

    - by Gengrlin
    Hi I have Map of String values. I want to cast this value at runtime. e.g. Map map = new HashMap(); map.put("key1","101"); map.put("key2","45.40"); Now runtime I know key1 is integer and key2 is double How can I cast this. I tried this: ("101").getClass().cast(Integer). Thanks.

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  • Difference between a Deprecated and an Legacy API?

    - by Vaibhav Bajpai
    I was studying the legacy API's in the Java's Collection Framework and I learnt that classes such as Vector and HashTable have been superseded by ArrayList and HashMap. However still they are NOT deprecated, and deemed as legacy when essentially, deprecation is applied to software features that are superseded and should be avoided, so, I am not sure when is a API deemed legacy and when it is deprecated.

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  • confusing java data structures

    - by London
    Maybe the title is not appropriate but I couldn't think of any other at this moment. My question is what is the difference between LinkedList and ArrayList or HashMap and THashMap . Is there a tree structure already for Java(ex:AVL,Black-white) or balanced or not balanced(linked list). If this kind of question is not appropriate for SO please let me know I will delete it. thank you

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  • Java Cloud Service Integration using Web Service Data Control

    - by Jani Rautiainen
    Java Cloud Service (JCS) provides a platform to develop and deploy business applications in the cloud. In Fusion Applications Cloud deployments customers do not have the option to deploy custom applications developed with JDeveloper to ensure the integrity and supportability of the hosted application service. Instead the custom applications can be deployed to the JCS and integrated to the Fusion Application Cloud instance.This series of articles will go through the features of JCS, provide end-to-end examples on how to develop and deploy applications on JCS and how to integrate them with the Fusion Applications instance.In this article a custom application integrating with Fusion Application using Web Service Data Control will be implemented. v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";} Pre-requisites Access to Cloud instance In order to deploy the application access to a JCS instance is needed, a free trial JCS instance can be obtained from Oracle Cloud site. To register you will need a credit card even if the credit card will not be charged. To register simply click "Try it" and choose the "Java" option. The confirmation email will contain the connection details. See this video for example of the registration. Once the request is processed you will be assigned 2 service instances; Java and Database. Applications deployed to the JCS must use Oracle Database Cloud Service as their underlying database. So when JCS instance is created a database instance is associated with it using a JDBC data source. The cloud services can be monitored and managed through the web UI. For details refer to Getting Started with Oracle Cloud. JDeveloper JDeveloper contains Cloud specific features related to e.g. connection and deployment. To use these features download the JDeveloper from JDeveloper download site by clicking the “Download JDeveloper 11.1.1.7.1 for ADF deployment on Oracle Cloud” link, this version of JDeveloper will have the JCS integration features that will be used in this article. For versions that do not include the Cloud integration features the Oracle Java Cloud Service SDK or the JCS Java Console can be used for deployment. For details on installing and configuring the JDeveloper refer to the installation guide. For details on SDK refer to Using the Command-Line Interface to Monitor Oracle Java Cloud Service and Using the Command-Line Interface to Manage Oracle Java Cloud Service. Create Application In this example the “JcsWsDemo” application created in the “Java Cloud Service Integration using Web Service Proxy” article is used as the base. Create Web Service Data Control In this example we will use a Web Service Data Control to integrate with Credit Rule Service in Fusion Applications. The data control will be used to query data from Fusion Applications using a web service call and present the data in a table. To generate the data control choose the “Model” project and navigate to "New -> All Technologies -> Business Tier -> Data Controls -> Web Service Data Control" and enter following: Name: CreditRuleServiceDC URL: https://ic-[POD].oracleoutsourcing.com/icCnSetupCreditRulesPublicService/CreditRuleService?WSDL Service: {{http://xmlns.oracle.com/apps/incentiveCompensation/cn/creditSetup/creditRule/creditRuleService/}CreditRuleService On step 2 select the “findRule” operation: Skip step 3 and on step 4 define the credentials to access the service. Do note that in this example these credentials are only used if testing locally, for JCS deployment credentials need to be manually updated on the EAR file: Click “Finish” and the proxy generation is done. Creating UI In order to use the data control we will need to populate complex objects FindCriteria and FindControl. For simplicity in this example we will create logic in a managed bean that populates the objects. Open “JcsWsDemoBean.java” and add the following logic: Map findCriteria; Map findControl; public void setFindCriteria(Map findCriteria) { this.findCriteria = findCriteria; } public Map getFindCriteria() { findCriteria = new HashMap(); findCriteria.put("fetchSize",10); findCriteria.put("fetchStart",0); return findCriteria; } public void setFindControl(Map findControl) { this.findControl = findControl; } public Map getFindControl() { findControl = new HashMap(); return findControl; } Open “JcsWsDemo.jspx”, navigate to “Data Controls -> CreditRuleServiceDC -> findRule(Object, Object) -> result” and drag and drop the “result” node into the “af:form” element in the page: On the “Edit Table Columns” remove all columns except “RuleId” and “Name”: On the “Edit Action Binding” window displayed enter reference to the java class created above by selecting “#{JcsWsDemoBean.findCriteria}”: Also define the value for the “findControl” by selecting “#{JcsWsDemoBean.findControl}”. Deploy to JCS For WS DC the authentication details need to be updated on the connection details before deploying. Open “connections.xml” by navigating “Application Resources -> Descriptors -> ADF META-INF -> connections.xml”: Change the user name and password entry from: <soap username="transportUserName" password="transportPassword" To match the access details for the target environment. Follow the same steps as documented in previous article ”Java Cloud Service ADF Web Application”. Once deployed the application can be accessed with URL: https://java-[identity domain].java.[data center].oraclecloudapps.com/JcsWsDemo-ViewController-context-root/faces/JcsWsDemo.jspx When accessed the first 10 rules in the system are displayed: Summary In this article we learned how to integrate with Fusion Applications using a Web Service Data Control in JCS. In future articles various other integration techniques will be covered. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}

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  • Texture switching with a entity system

    - by GameDev-er
    I'm using thinking of using an entity system in my game. So far I've been using Artemis with success. However, I have a question about texture switching. I read that switching textures too often is bad. So I load all the textures when the game loads like so: import org.newdawn.slick.opengl.TextureLoader; ... public HashMap<String, Texture> Textures; ... Then for each texture I do this: Texture tex = TextureLoader.getTexture("PNG", this.getClass().getResourceAsStream(texturePath)); Textures.put(textureName, tex); Then when drawing entities I do this: drawEntity() { glBindTexture(GL_TEXTURE_2D, Textures.get(entityTexture).getTextureID()); ... } Say I have 50 entities, using 10 different 3D models, each with their own texture. When the drawEntity system runs, it doesn't group by which entities use which texture. So I could be switching textures before drawing each entity! Is there a more efficient way to switch textures between entities? Or is glBindTexture() a good option?

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  • Overriding GetHashCode in a mutable struct - What NOT to do?

    - by Kyle Baran
    I am using the XNA Framework to make a learning project. It has a Point struct which exposes an X and Y value; for the purpose of optimization, it breaks the rules for proper struct design, since its a mutable struct. As Marc Gravell, John Skeet, and Eric Lippert point out in their respective posts about GetHashCode() (which Point overrides), this is a rather bad thing, since if an object's values change while its contained in a hashmap (ie, LINQ queries), it can become "lost". However, I am making my own Point3D struct, following the design of Point as a guideline. Thus, it too is a mutable struct which overrides GetHashCode(). The only difference is that mine exposes and int for X, Y, and Z values, but is fundamentally the same. The signatures are below: public struct Point3D : IEquatable<Point3D> { public int X; public int Y; public int Z; public static bool operator !=(Point3D a, Point3D b) { } public static bool operator ==(Point3D a, Point3D b) { } public Point3D Zero { get; } public override int GetHashCode() { } public override bool Equals(object obj) { } public bool Equals(Point3D other) { } public override string ToString() { } } I have tried to break my struct in the way they describe, namely by storing it in a List<Point3D>, as well as changing the value via a method using ref, but I did not encounter they behavior they warn about (maybe a pointer might allow me to break it?). Am I being too cautious in my approach, or should I be okay to use it as is?

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