Using java.util.Arrays.binarySearch

Hi,
I tried the following code
import java.util.Arrays ;
class SecondTry {
public static void main(java.lang.String args[]) {
int xyz[] = new int[10];
xyz[0] = 5;
xyz[1] = 6;
xyz[2] = 1;
Arrays.sort(xyz);
System.out.println(Arrays.binarySearch(xyz,5));
i expected to see a result of 1. But i get a 8.
I am sure i must be doing something wrong. But not able to figure out what exactly is wrong. Could somebody help?
TIA,
Babu

hi there,
.The output was 8 because u have declared the array size to be 10,so the values which are not assigned would be assigned to zero,so if you change the array size to 3,u would get the desired output :)
cheers
class SecondTry {
public static void main(java.lang.String args[]) {
int xyz[] = new int[3]; //change to three
xyz[0] = 5;
xyz[1] = 6;
xyz[2] = 1;
Arrays.sort(xyz);
System.out.println(Arrays.binarySearch(xyz,5));

Similar Messages

Java.util.Arrays.sort for Vector

I used the java.util.Arrays.sort to sort an array based on the method below.
              java.util.Arrays.sort(array, 0, total, new ComparatorX());
           repaint();
            class ComparatorX implements java.util.Comparator
          public int compare( Object p1, Object p2){
               int x1=((Point)p1).x;
               int x2=((Point)p2).x;
               if(x1>x2)
                            return 1;
               if(x1>x2)
                            return -1;
               return 0;
     }I've since changed the array to a vector. Is there anyway I can keep the comparator. Or how can I sort the vector based on the above method.

BTW: Don't know if it's just a typing mistake, but your code contains an error:
class ComparatorX implements java.util.Comparator     {
   public int compare( Object p1, Object p2) {
      int x1=((Point)p1).x;
      int x2=((Point)p2).x;
      if (x1>x2) {
         return 1;
      if (x1>x2) { // Should be: if (x2 > x1) ...
         return -1;
      return 0;

Java.util.Array

Exception in thread "main" java.lang.ClassCastException: Card
at java.util.Arrays.mergeSort(Arrays.java:1044)
at java.util.Arrays.sort(Arrays.java:997)
at CardPlayer.sortHand(CardPlayer.java:91)
at Game.main(Game.java:75)
i get this error message after I call a sort method using the java.util.Array
does anyone know why, or do u need more code?
thanks

The Card object needs to implement the Comparable interface if an array of them is to be sorted. The ClassCastException occurs when the sorting code attempts to assign a Card Object to a Comparable variable. The API documentation refers to this problem like this:
Throws:
ClassCastException - if the array contains elements that are not mutually comparable (for example, strings and integers).

Trouble extending java.util.Arrays

I have written some utility functions for dealing with arrays and I would like to bundle them into a class along with java's built-in array functions (java.util.Arrays). To do this, I tried to extends the class java.util.Arrays like this:
public class ArrayUtils extends java.util.Arrays
/* some static methods */
When I try to compile this with javac (even with no class body between the braces), I get an error "error:Cannot find constructor "Arrays" with matching parameters [JLS 15.12]". Does anyone know what's going on here? Why is the compiler looking for a constructor? And why can't it find one? I would very much appreciate your insight. Thanks. Eli

Does anyone know what's
going on here? Why is the compiler looking for a
constructor? And why can't it find one?Conceputually....
Inheritance exists to allow one to inherit from an object. In java objects can be created by using a class. However classes in java do not have to be objects. And you are trying to inherit from something that is not an object.
One of the other uses for class in java is to group a number of convienent functions together. (Grouped functions do NOT represent a class.) That is what java.util.Arrays is.
Technically....
The class java.util.Arrays has a private constructor which means you can't derive anything from it.

Private static ArrayList within java.util.Arrays

I was recently reviewing the code in java.util.Arrays (class version 1.45 - Java version 1.4.1). Beginning on line 2289 is a private static class named ArrayList. I'm completely baffled as to why the author created this slimmed-down private class (which would be, incidentally, returned by the Arrays.asList(Object[] a) method) rather than use the public class java.util.ArrayList. Can anyone offer an explanation?
Thanks,
John

from JDK JAVADoc:
asList
public static List asList(Object[] a)
Returns a fixed-size list backed by the specified array. (Changes to the returned list "write through" to the array.) This method acts as bridge between array-based and collection-based APIs, in combination with Collection.toArray. The returned list is serializable.
So the private ArrayList extends java.util.ArrayList, and any changes made this list does not affect the internal Object[].... in other words can not be changed.

Problem in Creating a jar file using java.util.jar and deploying in jboss 4

Dear Techies,
I am facing this peculiar problem. I am creating a jar file programmatically using java.util.jar api. The jar file is created but Jboss AS is unable to deploy this jar file. I have also tested that my created jar file contains the same files. When I create a jar file from the command using jar -cvf command, Jboss is able to deploy. I am sending the code , please review it and let me know the problem. I badly require your help. I am unable to proceeed in this regard. Please help me.
package com.rrs.corona.solutionsacceleratorstudio.solutionadapter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.jar.JarEntry;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;
import com.rrs.corona.solutionsacceleratorstudio.SASConstants;
* @author Piku Mishra
public class JarCreation
     * File object
     File file;
     * JarOutputStream object to create a jar file
     JarOutputStream jarOutput ;
     * File of the generated jar file
     String jarFileName = "rrs.jar";
     *To create a Manifest.mf file
     Manifest manifest = null;
     //Attributes atr = null;
     * Default Constructor to specify the path and
     * name of the jar file
     * @param destnPath of type String denoting the path of the generated jar file
     public JarCreation(String destnPath)
     {//This constructor initializes the destination path and file name of the jar file
          try
               manifest = new Manifest();
               jarOutput = new JarOutputStream(new FileOutputStream(destnPath+"/"+jarFileName),manifest);
          catch(Exception e)
               e.printStackTrace();
     public JarCreation()
     * This method is used to obtain the list of files present in a
     * directory
     * @param path of type String specifying the path of directory containing the files
     * @return the list of files from a particular directory
     public File[] getFiles(String path)
     {//This method is used to obtain the list of files in a directory
          try
               file = new File(path);
          catch(Exception e)
               e.printStackTrace();
          return file.listFiles();
     * This method is used to create a jar file from a directory
     * @param path of type String specifying the directory to make jar
     public void createJar(String path)
     {//This method is used to create a jar file from
          // a directory. If the directory contains several nested directory
          //it will work.
          try
               byte[] buff = new byte[2048];
               File[] fileList = getFiles(path);
               for(int i=0;i<fileList.length;i++)
                    if(fileList.isDirectory())
                         createJar(fileList[i].getAbsolutePath());//Recusive method to get the files
                    else
                         FileInputStream fin = new FileInputStream(fileList[i]);
                         String temp = fileList[i].getAbsolutePath();
                         String subTemp = temp.substring(temp.indexOf("bin")+4,temp.length());
//                         System.out.println( subTemp+":"+fin.getChannel().size());
                         jarOutput.putNextEntry(new JarEntry(subTemp));
                         int len ;
                         while((len=fin.read(buff))>0)
                              jarOutput.write(buff,0,len);
                         fin.close();
          catch( Exception e )
               e.printStackTrace();
     * Method used to close the object for JarOutputStream
     public void close()
     {//This method is used to close the
          //JarOutputStream
          try
               jarOutput.flush();
               jarOutput.close();
          catch(Exception e)
               e.printStackTrace();
     public static void main( String[] args )
          JarCreation jarCreate = new JarCreation("destnation path where jar file will be created /");
          jarCreate.createJar("put your source directory");
          jarCreate.close();

Hi,
I have gone through your code and the problem is that when you create jar it takes a complete path address (which is called using getAbsolutePath ) (when you extract you see the path; C:\..\...\..\ )
You need to truncate this complete path and take only the path address where your files are stored and the problem must be solved.

How do I estimate time takes to Zip/Unzip using java.util.zip ?

If I am compressing files or uncompressing zips using java.util.zip is there a way for me to tell the user how long it should take or for perhaps displaying a progress monitor ?

For unzip use the ZipInputStream and pass it a CountingInputStream that keeps track ofr the number of bytes read from it (you write this). This CountingInputStream extends fileInputStream and as such can provide you with information about the total number of bytes available to be read and the number already read. This can give a crude idea of how much work has been done and how much work still needs to be done. It is inaccurate but should be good enoough for a progress bar
As for zipping use the ZipOutputStream and pass it blocks of information. Keep track of the number of blocks you have written and the number you still need to write.
matfud

Using java.util.zip.ZipFile

I have files that are about 4GB (with possible growth in the future) that will be sent to a file system and a java process will be used to unzip them.
Is there a size limit for unzipping files using java.util.zip.ZipFile?
annie

Chicon wrote:
Hi annie613,
Indeed, there's a size limit of 2GB for unzipping files, more precisely when the size of the inflated file reaches 2GB !
Edit : inflated instead of deflated
Edited by: Chicon on Jun 29, 2009 3:56 PMHmm, this blog says that the current limit of 4GB has been expanded by implementing ZIP64 support in OpenJDK7 build(b55).
[http://blogs.sun.com/xuemingshen/entry/zip64_support_for_4g_zipfile]

How to set property "java.util.Arrays.useLegacyMergeSort" in jnlp-file?

Hi,
I have a problem in a web start application with java 7 and the new sort behavior (exception: comparison method violates its general contract).
So I like to go back to previous behavior and tried to put the new java 7 system property "java.util.Arrays.useLegacyMergeSort" in the generated jnlp-File:
<property name="java.util.Arrays.useLegacyMergeSort" value="true"/>.
Now I can read the property value in java code with System.getProperty("java.util.Arrays.useLegacyMergeSort"), and guess the property was successful set, but the exception still appears?!
The system property works with command line "javaws -J-Djava.util.Arrays.useLegacyMergeSort=true file.jnlp", but not via doubleclick on the jnlp-file or url and browser.
Any ideas?
Cheers,
Dan

Only "trusted" set of properties can be set in the JNLP file by unsigned applications.
List of properties is revised from time to time but it usually takes time for new properties to be added to it (if there is strong demand for it as every property should undergo security audit).
You can specify arbitrary property if you sign your application and JNLP file.

Unzipping files using java.util

I am trying to unzip files using java.util.zip
It works fine when I am trying to unzip a file that is already residing on the server.
But I want to unzip the file that user will upload to the server .
My code is uploading zip file to server but not able to unzip this zip file giving error
java.util.zip.ZipException: error in opening zip file
What could be the problem
I am not getting exactly
Can you give me any clue
Thanks

sounds like the uploading is the problem. Are you FTPing the file? If so check that it's being transferred in binary, not ascii.

Modifying JAR file using java.util.jar package over the network

Hello,
I am modifying a JAR file programmatically using java.util.jar package. The time taken to save the contents to a local disk is very less (around 1 sec) . When I tried modifying the JAR from a remote machine over the network (from mapped drive or shared folder of WIN NT), the time taken to save is 15-20 times more.
I am recreating the whole JAR while modifying. Is there any way to improve the performance. Or is it possible to write only the changed files?
Thanks,
Prasad Y S.

When you "update" a jar file, you must always recreate it from scratch.

Help:how to use java.util.jar to zip or unzip a binary file.

how to use java.util.jar to zip or unzip a binary file or a file contain native code.

It may help you to know how I add JARs
1. I open my Project (myProject)
2. I Mount the JAR to the FileSystem (like mypackages.jar = which includes com.mus.de.myClass.java)
3. I Mount the File to the FileSystem (like c:\..myfiles..\myProject)
3.1 I add the File to my Project
4. I select File | New -> Classes | Main
4.1 I typed "import com.mus.de.myClass.java" to refer to this package.
4.2 I called some of the public methods
thats it
Andreas

How can I use java.util.Date and change display format.

Hello All,
I want to use java.util.Date in View Context and in Custom Control Context of Web dynpro java. When i mapped of a Input Field to the java.util.Date then message shows that its not supported. Plz suggest me how to handle Date with different formats ??

If you always want the user to enter the date in dd/MM/yyyy, you can do the following.
Goto Local Dictonary -> Simple types in your project and create a type known as "InputDate" (or whatever you feel) of built-in type 'Date'.
Now specifiy its format in the 'Representation' tab as "dd/MM/yyyy" (case-senstive).
Now declare a value attribute say "inputdate" in your context with this type and bind the inputfield to this context value attribute.
This will solve your problem.
But if you want the user to input date depending on the region he belongs, change the default locale date in Control Panel->Regional and Language Options->Change to English(UK) -> Customize -> Date Tab -> Sort Date Format to dd/MM/yyyy.
Now clear the cache, delete temporary files and restart the machine. This should solve the problem.

AsList(java.lang.Object[]) in java.util.Arrays cannot be applied to (int[])

hi all,
i'm getting the above error msg when trying to compile a simple array prog...
while at it, is there another simple way to print the contents
of an array to the console in a single statement except using the asList method??? .. like :
int[] myArray = {1,2,3,4};
System.out.println(myArray);
==================================
here's the code for my program :-
tks in advance.
import java.util.*;
public class ListArray {
public static void main(String args[]) {
     int[] anArray = {2,7,5,8,3};
     for (int i = 0; i < anArray.length; i++) {
     System.out.println("Element No : " + (i+1) + " = " + anArray);
     System.out.println("All the Elements : " + Arrays.asList(anArray));

Funnily enough, thats because int[] is not an array of Objects.
You can make your listing method work by writing this instead:
for (int index = 0; index < anArray.length; index++) {
System.out.println("Element No: " + (index + 1) + " = " + anArray[index]);
}

Using java.util.logging Properly

Hello,
I have implemented java.util.logging in my application by creating a kind of "wrapper" class that I call for handling logging. It doesn't extend the logging classes, it just provides an object with helper methods that I can call when I want it.
public class LogCleanerLogger {
    private static final String cleanerLogfile = "logcleanerlog%g.txt";
    private static final String loggerName = "LogCleaner";
    private Logger cleanerLogger = null;
    public LogCleanerLogger() throws IOException{
        this.cleanerLogger = Logger.getLogger(getLoggerName());
        cleanerLogger.setUseParentHandlers(false);
        FileHandler logFile = new FileHandler(getCleanerLogfile(),10000,1, true);
        logFile.setFormatter(new SimpleFormatter());
        cleanerLogger.addHandler(logFile);
    public void writeLogInfoMessage(String message){
        cleanerLogger.info(message);
    public void writeLogWarningMessage(String message){
        cleanerLogger.warning(message);
    public void writeLogErrorMessage(String message){
        cleanerLogger.severe(message);
// getters and setters
} // end class    This all works quite happily and I can log any information I want. Except for one thing -- my log directory ends up with the log file (logcleanerlog0.txt) and a list of what appear to be temporary logs, e.g. logcleanerlog0.txt.1, logcleanerlog0.txt.2, and so on. Each increment of the number corresponds to a log file that has progressively less information in it that the previous one. At the top level, the unnumbered log, logcleanerlog0.txt, has all the logged information in it.
I cannot make out, from reading the API and other documentation, how I can get rid of these other files, which appear to me to be temporary files used in the construction of the top level file.
Can someone help me by explaining the mechanism for generating these files and either (a) how I can get rid of them altogether or (b) how I can arrange for them to be generated in a temp dir, while keeping the main log in the present directory (application root).
Or perhaps there is a "better way" (that is equally as easy, of course ;-).
Thanks.
mp

are you sure you cannot use the classes from a newer
version. You can put those classes in your own
directory. If there ar some other classes that need to
be from the newer version, you can include them, also
in your project. It is important that your project
directory to be placed in the classpath variable
before the jdk jars.
(this solution might not work)I doubt that is worth trying.
First, although it probably does not apply in this case, you are not allowed to distribute part of a JVM. So you could never use this solution in a commercial application.
Secondly the Java API does change. And every execution path that might use the changed code would have to be tested. That is going to take a lot of work. Keep in mind that the logging api uses java.lang.String and java.lang.String definitely changed in 1.4 and almost every class in the Java API uses it.

Using java.util.Arrays.binarySearch

Similar Messages

Maybe you are looking for