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Thread: Help with password generation

  1. #1
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    Post Help with password generation

    I'm making a program to generate a random password with the desired length and chars.

    All went smooth until i got to the generation itself. The error exists in this code:

    package generate;
     
    import gui.PassPanel;
     
    import java.util.Random;
     
    public class GeneratePass {
     
    	private final String[] letters = new String[] {
    			"a","A","b","B","c","C","d","D","e","E","f","F","g","G","h","H",
    			"i","I","j","J","k","K","l","L","m","M","n","N","o","O","p","P",
    			"q","Q","r","R","s","S","t","T","u","U","v","V","w","W","x","X",
    			"y","Y","z","Z"
    	};
     
    	private final String[] numbers = new String[] {
    			"0","1","2","3","4","5","6","7","8","9"
    	};
     
    	private final String[] both = new String[] {
    			"a","A","b","B","c","C","d","D","e","E","f","F","g","G","h","H",
    			"i","I","j","J","k","K","l","L","m","M","n","N","o","O","p","P",
    			"q","Q","r","R","s","S","t","T","u","U","v","V","w","W","x","X",
    			"y","Y","z","Z","0","1","2","3","4","5","6","7","8","9"
    	};
     
    	String pass = "";
     
    	public GeneratePass(String chars, int length) {
    		String[] charsUsing;
    		if (chars.equals("both")) {
    			charsUsing = both;
    		}
    		else if (chars.equals("letters")) {
    			charsUsing = letters;
    		}
    		else{
    			charsUsing = numbers;
    		}
     
    		Random r = new Random(charsUsing.length);
     
    		for (int i = 0; i < length; i++) {
    			pass = pass + charsUsing[r.nextInt()];
    		}
     
    		PassPanel.setPassword(pass);
    	}
    }

    And I get this exception:

     
    Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1165488049
    at generate.GeneratePass.<init>(GeneratePass.java:44)
    at gui.PassPanel$MyOkButtonListener.actionPerformed(P assPanel.java:103)
    at javax.swing.AbstractButton.fireActionPerformed(Abs tractButton.java:2012)
    at javax.swing.AbstractButton$Handler.actionPerformed (AbstractButton.java:2335)
    at javax.swing.DefaultButtonModel.fireActionPerformed (DefaultButtonModel.java:404)
    at javax.swing.DefaultButtonModel.setPressed(DefaultB uttonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseRe leased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.jav a:6268)
    at javax.swing.JComponent.processMouseEvent(JComponen t.java:3267)
    at java.awt.Component.processEvent(Component.java:603 3)
    at java.awt.Container.processEvent(Container.java:204 5)
    at java.awt.Component.dispatchEventImpl(Component.jav a:4629)
    at java.awt.Container.dispatchEventImpl(Container.jav a:2103)
    at java.awt.Component.dispatchEvent(Component.java:44 55)
    at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:4633)
    at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:4297)
    at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:4227)
    at java.awt.Container.dispatchEventImpl(Container.jav a:2089)
    at java.awt.Window.dispatchEventImpl(Window.java:2517 )
    at java.awt.Component.dispatchEvent(Component.java:44 55)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.j ava:649)
    at java.awt.EventQueue.access$000(EventQueue.java:96)
    at java.awt.EventQueue$1.run(EventQueue.java:608)
    at java.awt.EventQueue$1.run(EventQueue.java:606)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:105)
    at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:116)
    at java.awt.EventQueue$2.run(EventQueue.java:622)
    at java.awt.EventQueue$2.run(EventQueue.java:620)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:105)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java: 619)
    at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:275)
    at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:200)
    at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:190)
    at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:185)
    at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:177)
    at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:138)




    It points to this line of code:


    pass = pass + charsUsing[r.nextInt()];

    Please help me!
    Last edited by Dr.Code; June 26th, 2012 at 10:54 AM.


  2. #2
    Super Moderator Sean4u's Avatar
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    Default Re: Help with password generation

    You just need to re-read the API documentation for Random. The constructor you're using doesn't do what you think it does. Nor does Random.nextInt(). The fix is to select the correct constructor and the correct int-returning method from Random's API

  3. The Following User Says Thank You to Sean4u For This Useful Post:

    Dr.Code (June 26th, 2012)

  4. #3
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    Default Re: Help with password generation

    Quote Originally Posted by Sean4u View Post
    You just need to re-read the API documentation for Random. The constructor you're using doesn't do what you think it does. Nor does Random.nextInt(). The fix is to select the correct constructor and the correct int-returning method from Random's API
    Thank you! I see what I did now and it works perfect, thanks!

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