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  • Java NumberFormatException

    - by Bragaadeesh
    Hi, I am trying to do a conversion of a String to integer for which I get a NumberFormatException. The reason is pretty obvious. But I need a workaround here. Following is the sample code. public class NumberFormatTest { public static void main(String[] args) { String num = "9.18E+09"; try{ long val = Long.valueOf(num); }catch(NumberFormatException ne){ //Try to convert the value to 9180000000 here } } } I need the logic that goes in the comment section, a generic one would be nice. Thanks.

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  • Inheritance in Java

    - by Mandar
    Hello, recently I went through the inheritance concept. As we all know, in inheritance, superclass objects are created/initialized prior to subclass objects. So if we create an object of subclass, it will contain all the superclass information. But I got stuck at one point. Do the superclass and the subclass methods are present on separate call-stack? If it is so, is there any specific reason for same? If it is not so, why they don't appear on same call-stack? E.g. // Superclass class A { void play1( ) { // .... } } // Subclass class B extends A { void play2( ) { //..... } } Then does the above 2 methods i.e play1( ) and play2( ) appear on separate call stack? Thanks.

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  • is this possible in java or any other programming language

    - by drake
    public abstract class Master { public void printForAllMethodsInSubClass() { System.out.println ("Printing before subclass method executes"); } } public class Owner extends Master { public void printSomething () { System.out.println ("This printed from Owner"); } public int returnSomeCals () { return 5+5; } } Without messing with methods of subclass...is it possible to execute printForAllMethodsInSubClass() before the method of a subclass gets executed?

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  • Multiple threads modifying a collection in Java??

    - by posdef
    Hi, The project I am working on requires a whole bunch of queries towards a database. In principle there are two types of queries I am using: read from excel file, check for a couple of parameters and do a query for hits in the database. These hits are then registered as a series of custom classes. Any hit may (and most likely will) occur more than once so this part of the code checks and updates the occurrence in a custom list implementation that extends ArrayList. for each hit found, do a detail query and parse the output, so that the classes created in (I) get detailed info. I figured I would use multiple threads to optimize time-wise. However I can't really come up with a good way to solve the problem that occurs with the collection these items are stored in. To elaborate a little bit; throughout the execution objects are supposed to be modified by both (I) and (II). I deliberately didn't c/p any code, as it would be big chunks of code to make any sense.. I hope it make some sense with the description above. Thanks,

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  • Where do you start your design - code, UI or workflow?

    - by Mmarquee
    Hi I was discussing this at work, and was wondering where people start their designs? We tend to start with designing code to solve the problem presented to us, but that is probably all of us are (or were) programmers. I was wondering where other people and organisations start their design. Do they start with solving the problem as a coding problem, sit down and design what UI to use, or map out the data or workflow? Thanks

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  • Variable Assignment and loops (Java)

    - by Raven Dreamer
    Greetings Stack Overflowers, A while back, I was working on a program that hashed values into a hashtable (I don't remember the specifics, and the specifics themselves are irrelevant to the question at hand). Anyway, I had the following code as part of a "recordInput" method. tempElement = new hashElement(someInt); while(in.hasNext() == true) { int firstVal = in.nextInt(); if (firstVal == -911) { break; } tempElement.setKeyValue(firstVal, 0); for(int i = 1; i<numKeyValues;i++) { tempElement.setKeyValue(in.nextInt(), i); } elementArray[placeValue] = tempElement; placeValue++; } // close while loop } // close method This part of the code was giving me a very nasty bug -- no matter how I finagled it, no matter what input I gave the program, it would always produce an array full of only a single value -- the last one. The problem, as I later determined it, was that because I had not created the tempElement variable within the loop, and because values were not being assigned to elementArray[] until after the loop had ended -- every term was defined rather as "tempElement" -- when the loop terminated, every slot in the array was filled with the last value tempElement had taken. I was able to fix this bug by moving the declaration of tempElement within the while loop. My question to you, Stackoverflow, is whether there is another (read: better) way to avoid this bug while keeping the variable declaration of tempElement outside the while loop. (suggestions for better title and tags also appreciated)

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  • Finding the actual runtime call tree of a Java Program

    - by Chathuranga Chandrasekara
    Suppose I have a big program that consists of hundreds of methods in it. And according to the nature of input the program flow is getting changed. Think I want to make a change to the original flow. And it is big hassle to find call hierarchy/ references and understand the flow. Do I have any solution for this within Eclipse? Or a plugin? As an example, I just need a Log of method names that is in order of time. Then I don't need to worry about the methods that are not relevant with my "given input" Update : Using debug mode in eclipse or adding print messages are not feasible. The program is sooooo big. :)

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  • Example of ==, equals and hashcode in java

    - by Abhishek Jain
    Given this: String s1= new String("abc"); String s2= new String("abc"); String s3 ="abc"; System.out.println(s1==s3); System.out.println(s1==s2); System.out.println(s1.equals(s2)); System.out.println(s1.equals(s3)); System.out.println(s1.hashCode()); System.out.println(s2.hashCode()); System.out.println(s3.hashCode()); Output is: false false true true 96354 96354 96354 Here == is giving false for each object but hashcode for each String object is same. Why is it so?

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  • get eigenvalue pca with java

    - by Muhamad Burhanudin
    I try use PCA to reduce dimention, and i use jama for help me using matrix. but, i got problem when get eigenvalue with jama. for example i hava 2 image dimention 100x100, then i create single matrix 2 image x (100x100). there is 20.000 pixel. and how to get reduction with eigenvalue? this is sample my code : public static void main(String[] args) { BufferedImage bi; int[] rgb; int R, G, B; // int[] jum; double[][] gray = new double[500][500] ; String[] baris = new String[1000]; try { //bi = ImageIO.read(new File("D:\\c.jpg")); int[][] pixelData = new int[bi.getHeight() * bi.getWidth()][3]; int counter = 0; for (int i = 0; i < bi.getHeight(); i++) { for (int j = 0; j < bi.getWidth(); j++) { gray[i][j] = getPixelData(bi, i, j); // R = getR(bi, i, j); //G = getG(bi, i, j); //B = getB(bi, i, j); //jum = R + G + B; // gray[counter] = Double.toString(R + G + B / 3); // System.out.println("Gray " +gray); //for (int k = 0; k < rgb.length; k++) { // pixelData[counter][k] = rgb[k]; // } counter++; } } } catch (IOException e) { e.printStackTrace(); } Matrix matrix = new Matrix(gray); PCA pca = new PCA(matrix); pca.getEigenvalue(6); String n = pca.toString(); System.err.println("nilai n "+n); //double dete = pcadete(matrix,3600); } private static int getPixelData(BufferedImage bi, int x, int y) { int argb = bi.getRGB(y, x); int r, g, b; int gray; int rgb[] = new int[]{ (argb >> 16) & 0xff, //red (argb >> 8) & 0xff, //green (argb) & 0xff //blue }; r = rgb[0]; g = rgb[1]; b = rgb[2]; gray = (r + g + b) / 3; System.out.println("gray: " + gray); return gray; } when i show eigenvalue in this code : PCA pca = new PCA(matrix); pca.getEigenvalue(6); String n = pca.toString(); System.err.println("nilai n "+n); Result is : nilai n PCA@c3e9e9 Can, u tell me what way to get eigenvalue and reduction dimension.

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  • Use Java Annotation not to run a method

    - by Michael Mao
    Hi all: I've got a method in my class only for testing purpose : private void printOut(String msg, Object value) { System.out.println(msg + value); } It is a wrapper method for System.out.println(); So I hope, with the use of Annotation, I can choose not to run this method during productive environment while still keep those diagnostic output ready if I am to switch back to debugging environment. Which Annotation shall I put on top of the method name?

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  • bounding java generics by 'super' keyword

    - by mohsenof
    Why I can use 'super' just with wildcards and not with type parameters? for example why in Collection interface they've not written toArray method like this interface Collection"<"T{ public "< S super T S[] toArray(S[] a){ } } (sorry, I don't know how to deal with "<")

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  • Java String.indexOf and empty Strings

    - by tmeisenh
    I'm curious why the String.indexOf is returning a 0 (instead of -1) when asking for the index of an empty string within a string. The Javadocs only say this method returns the index in this String of the specified string, -1 if the string isn't found. System.out.println("FOO".indexOf("")); // outputs 0 wtf!!! System.out.println("FOO".indexOf("bar")); // outputs -1 as expected System.out.println("FOO".indexOf("F")); // outputs 0 as expected System.out.println("".indexOf("")); // outputs 0 as expected, I think

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  • IBM RAD With Java 1.5 wont compile code with generics

    - by Matt1776
    Hello I have some code that has generic references in it and my IBM RAD IDE will not compile the code, instead treating it as an error. I have checked the version of the JRE its pointing to across all the Enterprise Project's and it is 1.5 which I am told does support generics. Also I checked that all the libraries for WAS were pointing to the correct version and that the Compiler Compliance Level was set correctly (which it was at 5.0 and i changed it to 6.0 with no luck either) Does anyone have any suggestions as to anything else I can try? I have issues like this with RAD all the time and I dont know about anyone else but they took eclipse and made it complicated and dysfunctional.

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  • Will this Java regex return a single result or multiple

    - by Blankman
    If my HTML is: <tr><td>....</td><hr></tr> <tr><td>....</td><hr></tr> <tr><td>....</td><hr></tr> <tr><td>....</td><hr></tr> <tr><td>....</td><hr></tr> <tr><td>....</td><hr></tr> If my regex is: Patterp p = Pattern.compile("<tr>(.*)<hr></tr>"); Should this get 1 result or all the individual rows? Is there a way to force it to get all the rows and not just the entire html from the top <tr> to the last instance of <hr></tr> ?

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  • Returning searched results in an array in Java without ArrayList

    - by Crystal
    I started down this path of implementing a simple search in an array for a hw assignment without knowing we could use ArrayList. I realized it had some bugs in it and figured I'd still try to know what my bug is before using ArrayList. I basically have a class where I can add, remove, or search from an array. public class AcmeLoanManager { public void addLoan(Loan h) { int loanId = h.getLoanId(); loanArray[loanId - 1] = h; } public Loan[] getAllLoans() { return loanArray; } public Loan[] findLoans(Person p) { //Loan[] searchedLoanArray = new Loan[10]; // create new array to hold searched values searchedLoanArray = this.getAllLoans(); // fill new array with all values // Looks through only valid array values, and if Person p does not match using Person.equals() // sets that value to null. for (int i = 0; i < searchedLoanArray.length; i++) { if (searchedLoanArray[i] != null) { if (!(searchedLoanArray[i].getClient().equals(p))) { searchedLoanArray[i] = null; } } } return searchedLoanArray; } public void removeLoan(int loanId) { loanArray[loanId - 1] = null; } private Loan[] loanArray = new Loan[10]; private Loan[] searchedLoanArray = new Loan[10]; // separate array to hold values returned from search } When testing this, I thought it worked, but I think I am overwriting my member variable after I do a search. I initially thought that I could create a new Loan[] in the method and return that, but that didn't seem to work. Then I thought I could have two arrays. One that would not change, and the other just for the searched values. But I think I am not understanding something, like shallow vs deep copying???....

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  • java version of python-dateutil

    - by elhefe
    Python has a very handy package that can parse nearly any unambiguous date and provides helpful error messages on a parse failure, python-dateutil. Comparison to the SimpleDateFormat class is not favorable - AFAICT SimpleDateFormat can only handle one exact date format and the error messages have no granularity. I've looked through the Joda API but it appears Joda is the same way - only one explicit format can be parsed at a time. Is there any package or library that reproduces the python-dateutil behavior? Or am I missing something WRT Joda/SimpleDateFormat?

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  • serialize/deserialize a LinkedHashMap (android) java

    - by user348058
    So i want to pass a LinkedHashMap to an intent. //SEND THE MAP Intent singlechannel = new Intent(getBaseContext(),singlechannel.class); singlechannel.putExtra("db",shows1);//perase to startActivity(singlechannel); //GET THE MAP LinkedHashMap<String,String> db = new LinkedHashMap<String,String>(); db=(LinkedHashMap<String,String>) getIntent().getSerializableExtra("db"); This one Worked Like a charm with HashMap. But with LinkedHashMap i got a problem I got a warning "Type safety: Unchecked cast from Serializable to LinkedHashMap" But i had this warning with HashMap too? Any ideas.Any help is much appreciated Also I just saw this. https://issues.apache.org/jira/browse/HARMONY-6498

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  • Java Layout Insets

    - by ikurtz
    board image the above is a board layout done by using gridbaglayout. i would like insets of 5 pixels around the whole board but not between each label. i scaned the api and havent come up with something that lets me do this. does this mean i have to nest my board gui inside another gridbaglayout with the insets desired? thank you.

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  • Java multiple connections downloading file

    - by weulerjunior
    Hello friends, I was wanting to add multiple connections in the code below to be able to download files faster. Could someone help me? Thanks in advance. public void run() { RandomAccessFile file = null; InputStream stream = null; try { // Open connection to URL. HttpURLConnection connection = (HttpURLConnection) url.openConnection(); // Specify what portion of file to download. connection.setRequestProperty("Range", "bytes=" + downloaded + "-"); // Connect to server. connection.connect(); // Make sure response code is in the 200 range. if (connection.getResponseCode() / 100 != 2) { error(); } // Check for valid content length. int contentLength = connection.getContentLength(); if (contentLength < 1) { error(); } /* Set the size for this download if it hasn't been already set. */ if (size == -1) { size = contentLength; stateChanged(); } // Open file and seek to the end of it. file = new RandomAccessFile("C:\\"+getFileName(url), "rw"); file.seek(downloaded); stream = connection.getInputStream(); while (status == DOWNLOADING) { /* Size buffer according to how much of the file is left to download. */ byte buffer[]; if (size - downloaded > MAX_BUFFER_SIZE) { buffer = new byte[MAX_BUFFER_SIZE]; } else { buffer = new byte[size - downloaded]; } // Read from server into buffer. int read = stream.read(buffer); if (read == -1) { break; } // Write buffer to file. file.write(buffer, 0, read); downloaded += read; stateChanged(); } /* Change status to complete if this point was reached because downloading has finished. */ if (status == DOWNLOADING) { status = COMPLETE; stateChanged(); } } catch (Exception e) { error(); } finally { // Close file. if (file != null) { try { file.close(); } catch (Exception e) { } } // Close connection to server. if (stream != null) { try { stream.close(); } catch (Exception e) { } } } }

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