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  • Cleanest way to build an SQL string in Java

    - by Vidar
    I want to build an SQL string to do database manipulation (updates, deletes, inserts, selects, that sort of thing) - instead of the awful string concat method using millions of "+"'s and quotes which is unreadable at best - there must be a better way. I did think of using MessageFormat - but its supposed to be used for user messages, although I think it would do a reasonable job - but I guess there should be something more aligned to SQL type operations in the java sql libraries. Would Groovy be any good? Any help much appreciated.

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  • String manupulation classic interview questions

    - by user189364
    Hi, I am scheduled to have an onsite interview so I am preparing few basic questions. According to the company profile, they are big on string manipulation questions. So far i am manually coded these functions: 1) String length, copy, concat, remove white space 2) Reverse 3) Anagrams 4) Palindrome Please can some can give me a list of more classic string questions which i can practice before going there.

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  • How can I partial compare two strings in C?

    - by Nazgulled
    Hi, Let's say I have the following content: Lorem Ipsum is simply dummy text of the printing and typesetting industry. How do I search for dummy or dummy text in that string using C? Is there any easy way to do it or only with strong string manipulation? All I need is to search for it and return a boolean with the result.

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  • Groovy / Scala / Java under the hood

    - by Jack
    I used Java for like 6-7 years, then some months ago I discovered Groovy and started to save a lot of typing.. then I wondered how certain things worked under the hood (because groovy performance is really poor) and understood that to give you dynamic typing every Groovy object is a MetaClass object that handles all the things that the JVM couldn't handle by itself. Of course this introduces a layer in the middle between what you write and what you execute that slows down everything. Then somedays ago I started getting some infos about Scala. How these two languages compare in their byte code translations? How much things they add to the normal structure that it would be obtained by plain Java code? I mean, Scala is static typed so wrapper of Java classes should be lighter, since many things are checked during compile time but I'm not sure about the real differences of what's going inside. (I'm not talking about the functional aspect of Scala compared to the other ones, that's a different thing) Can someone enlighten me? From WizardOfOdds it seems like that the only way to get less typing and same performance would be to write an intermediate translator that translates something in Java code (letting javac compile it) without alterating how things are executed, just adding synctatic sugar withour caring about other fallbacks of the language itself.

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  • Editing a .class file directly, playing around with opcodes

    - by echox
    Hi, today I just tried to play a little bit around with the opcodes in compiled java class file. After inserting iinc 1,1 the java virtual machine responds with: Exception in thread "main" java.lang.ClassFormatError: Truncated class file at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) at java.lang.ClassLoader.defineClass(ClassLoader.java:616) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.access$000(URLClassLoader.java:58) at java.net.URLClassLoader$1.run(URLClassLoader.java:197) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) Could not find the main class: Test. Program will exit. This is my example source code: public class Test { public static void main(String[] args) { int i = 5; i++; i++; i++; System.out.println("Number: " + i + "\n"); } } The opcode for an increment is 0x84 + 2 bytes for operands. There's only one section in the resulting class file, which contains 0x84: [..] 8401 0184 0101 8401 01[..] So I would translate this as: iinc 1,1 iinc 1,1 iinc 1,1 corresponding to my i++; i++; i++; I then tried to append just 840101 to increment the variable once more, but that didn't work and resulted in the ClassFormatError. Is there anything like a checksum for the class file? I looked up the format of a classfile in http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html but could not find anything which points out to some kind of bytes_of_classfile or something. I also don't understand why the error is "Truncated Class File", because I did append something :-) I know its not a good idea to edit class files directly, but I'm just interested on the VM internals here.

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  • Are frameworks using byte-code generation creating leaky abstractions?

    - by Gabriel Šcerbák
    My point is, if you don't understand the abstraction of a framework, you can still decompile it and understand it, because you know the language e.g. Java. However, when byte-code generation happens, you have to understand even a lower level - JVM level byte-codes. I am really affraid of using any of such frameworks, which are many. Most of the time I think the reason for byte-code generation is simply lack of language features such as metaprogramming. Do you agree? What is your opinion and argument? How do you take over the problem with leaky abstractions in those frameworks?

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  • How do you access byte level information in JavaScript?

    - by JustSmith
    The generally accepted answer is that you can't. However there is mounting evidence that this is not true based on the existence of projects that read in types of data that are not basic HTML types. Some projects that do this are the JavaScript version of ProtoBuf and Smokescreen. Smokescreen is a flash interpreter written in JS so if it is not possible to get at the bytes directly how are these projects working around this? The source to Smokescreen can be found here. I have looked it over but with JS not being my primary language right now the solution eludes me.

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  • Detect use of older Java libraries

    - by Tony Morris
    Is there a third party library to detect the use of a Java 1.5 library when compiling with a 1.5 compiler with -source 1.4 and -target 1.4? I could use a 1.4 rt.jar in the bootclasspath however I hope there is a better way. To be used, for example, to fail the compile/build if a newer library is used.

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  • Sun's JVM instruction speed table

    - by Pindatjuh
    Is there a benchmark available how much relative time each instruction costs in a single-thread, average-case scenario (either with or without JIT compiler), for the JVM (any version) by Sun? If there is not a benchmark already available, how can I get this information? E.g.: TIME iload_1 1 iadd 12 getfield 40 etc. Where getfield is equivalent to 40 iload_1 instructions.

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  • Simple image editor to select area of image as wallpaper

    - by Kevin
    I've spent way to many hours looking for software to do the following simple task, so now I'll ask. I need software that will open an image and put a 'crop box' on it. You can set the 'crop box' to standard screen resolutions (1024x768) or define a custom one. You can move the 'crop box' around on the image to select the area you want. You can re-size the 'crop box' (selecting a corner and dragging w/mouse) and it maintains the correct aspect ratio. You can save the area in the 'crop box' to use as the Windows background. (The software doesn't need to set it as the background, I can do that myself in Windows XP.) The free software sites (CNET.com, etc.) have lots of image editing software that do things much more complicated than this simple task. I've spent too many hours downloading them to see if they will do this particular task. The ones I've tried would require manual trial and error to get the part of an image that I want saved as an image, with the correct aspect ratio so Windows doesn't screw with it (stretch, tile, crop) when I select it as the wallpaper.

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  • Proving file creation dates

    - by Nils Munch
    In a weird case surrounding copyrights of a software system I have developed, I use the fact that I have all the source files of the system in question, created long before I joined the company that claims to own the system. The company being sued by yours truely says that I have simply manipulated to files to appear to be from that date. Is it even possible to fake or manipulate creation dates ? And if so, how can I "prove" that the files really are that old ? Luckily, I stored my project on GitHub, whick confirmed the fact that the files are from that era, but that is besides the point. I run purely Apple OS X.

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  • Export to excel - COMMA issue

    - by 6242Y
    I want to put a string in an excel sheet from my Export to excel function. However my string is as follows: string : Red, red wine Go to my head Make me forget that I Still need and on my excel I get unexpected results , column change after comma and also column change when there is no full stop in front of an UPPER CASE alphabet. The Upper case alphabets (without a full stop before them) are also causing this (Go , Make . Still) How can I solve this issue ? I tried removing the spaces after the comma as var desc = ""; if (o.Description.Contains(',')) { var trimmedSplits = new List<string>(); var splits = o.Description.Split(','); foreach (var stringBits in splits) { desc = desc + stringBits.Trim() + ","; } desc = desc.Remove(desc.Length - 1); } dtRow[(int)ProductRangeExportToExcel.Description] = desc;

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  • Despeckle line art

    - by Dour High Arch
    We have a number of line-art charts unfortunately saved as JPEGs. They are now riddled with distracting compression artifacts or "speckles". Is there any way of removing these? I do not have the original files and it will be very difficult to recreate them. I am running Windows 7 and tried Paint.Net; none of the filters help. Posterize washed out all the colors and leaves the speckles. Blur makes text unreadable. Noise Reduction wrecks antialiasing of curved lines, and perversely enhances the speckles, making them look like checkerboards. Yes, I have Googled for software to do this; there are many programs that advertise despeckling but, after my experience with Paint.Net, do not want to experiment with applications that show no before and after images. The only example I have seen that does what I want is from a Photoshop tutorial. I have dozens of files and the tutorial requires considerable manual fine-tuning. I would prefer to automate or batch-process this task. Commercial apps are fine, but I do not want to spend over $600 and learning a complex program for a single task.

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  • How Do I Parse a String?

    - by Russ
    I am new to bash, and I am creating a script that loops through the files in a directory and based on part of the filename, does something with the file, so far I have this: #!/bin/bash DIR="/Users/me/Documents/import/*" for f in "$DIR" do $t=?????? echo "Loading $f int $t..." done so $f will output something like this: /Users/me/Documents/import/time_dim-1272037430173 out of this, I want time_dim, the directory can be variable length and -1272037430173 is a fixed length (it's the unix timestamp btw). What is the best way to go about this?

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  • Not-quite-JSON string deserialization in Python

    - by cpharmston
    I get the following text as a string from an XML-based REST API 'd':4 'ca':5 'sen':1 'diann':2,6,8 'feinstein':3,7,9 that I'm looking to deserialize into a pretty little Python dictionary: { 'd': [4], 'ca': [5], 'sen': [1], 'diann': [2, 6, 8], 'feinstein': [3, 7, 9] } I'm hoping to avoid using regular expressions or heavy string manipulation, as this format isn't documented and may change. The best I've been able to come up with: members = {} for m in elem.text.split(' '): m = m.split(':') members[m[0].replace("'", '')] = map(int, m[1].split(',')) return members Obviously a terrible approach, but it works, and that's better than anything else I've got right now. Any suggestions on better approaches?

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  • Application leaking Strings?

    - by Jörg B.
    My .net application does some heavy string loading/manipulation and unfortunately the memory consumption keeps rising and rising and when looking at it with a profiler I see alot of unreleased string instances. Now at one point of time or another I do need all objects t hat do have these string fields, but once done, I could get rid of e.g. the half of it and I Dispose() and set the instances to null, but the Garbage Collector does not to pick that up.. they remain in memory (even after half an hour after disposing etc). Now how do I get properly rid of unneeded strings/object instances in order to release them? They are nowhere referenced anymore (afaik) but e.g. aspose's memory profiler says their distance to the gc's root is '3'?

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  • Most efficient way to remove special characters from string

    - by ObiWanKenobi
    I want to remove all special characters from a string. Allowed characters are A-Z (uppercase or lowercase), numbers (0-9), underscore (_), or the dot sign (.). I have the following, it works but I suspect (I know!) it's not very efficient: public static string RemoveSpecialCharacters(string str) { StringBuilder sb = new StringBuilder(); for (int i = 0; i < str.Length; i++) { if ((str[i] >= '0' && str[i] <= '9') || (str[i] >= 'A' && str[i] <= 'z' || (str[i] == '.' || str[i] == '_'))) sb.Append(str[i]); } return sb.ToString(); } What is the most efficient way to do this? What would a regular expression look like, and how does it compare with normal string manipulation? The strings that will be cleaned will be rather short, usually between 10 and 30 characters in length.

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  • image filters for iphone sdk development

    - by plsp
    Hi All, I am planning to develop an iphone app which makes use of image filters like blurring, sharpening,etc. I noticed that there are few approaches for this one, Use openGL ES. I even found an example code on apple iphone dev site. How easy is openGL for somebody who has never used it? Can the image filters be implemented using the openGL framework? There is a Quartz demo as well posted on apple iphone dev site. Has anybody used this framework for doing image processing? How is this approach compared to openGL framework? Don't use openGL and Quartz framework. Basically access the raw pixels from the image and do the manipulation myself. Make use of any custom built image processing libraries like this one. Do you know of any other libraries like this one? Can anybody provide insights/suggestions on which option is the best? Your opinions are highly appreciated. Thanks!

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  • Why is setting HTML5's CanvasPixelArray values ridiculously slow and how can I do it faster?

    - by Nixuz
    I am trying to do some dynamic visual effects using the HTML 5 canvas' pixel manipulation, but I am running into a problem where setting pixels in the CanvasPixelArray is ridiculously slow. For example if I have code like: imageData = ctx.getImageData(0, 0, 500, 500); for (var i = 0; i < imageData.length; i += 4){ imageData.data[i] = buffer[i]; imageData.data[i + 1] = buffer[i + 1]; imageData.data[i + 2] = buffer[i + 2]; } ctx.putImageData(imageData, 0, 0); Profiling with Chrome reveals, it runs 44% slower than the following code where CanvasPixelArray is not used. tempArray = new Array(500 * 500 * 4); imageData = ctx.getImageData(0, 0, 500, 500); for (var i = 0; i < imageData.length; i += 4){ tempArray[i] = buffer[i]; tempArray[i + 1] = buffer[i + 1]; tempArray[i + 2] = buffer[i + 2]; } ctx.putImageData(imageData, 0, 0); My guess is that the reason for this slowdown is due to the conversion between the Javascript doubles and the internal unsigned 8bit integers, used by the CanvasPixelArray. Is this guess correct? Is there anyway to reduce the time spent setting values in the CanvasPixelArray?

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