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  1. JDK
  2. JDK-4195583

NPE thrown in List.add() with null item

    Details

    • Subcomponent:
    • Resolved In Build:
      1.2.2
    • CPU:
      generic
    • OS:
      generic

      Description

      An NPE is thrown when List.add() is called with a null item as the
      argument. According to the spec, a null item is supposed to be treated
      as an empty string, "".

      /*
      */

      /**
       * ListNullTest.java
       *
       * summary:
       */

      import java.applet.Applet;
      import java.awt.*;
      import java.awt.event.*;


      public class ListNullTest extends Applet
       {
         List list;

         public void init()
          {
            this.setLayout (new BorderLayout ());

            list = new List(15);
            //list.add("");
            //list.add(null);
            list.add("", 0);
            //list.add("", 1);
            list.add((String) null, 1);
            System.out.println("Just added the null item");

            this.add("South", list);
            System.out.println("Just added the list");

            String[] instructions =
             {
               " This test program adds two items to a List: one with \"\" as the ",
               " item and one with null as the item. It then checks to see if the ",
               " List really handles the null item as \"\".",
               " ",
               " Instructions:",
               " ",
               " If no null pointer exception was thrown, the test passed. "
             };

            Sysout.createDialogWithInstructions( instructions );

          }//End init()

         public void start ()
          {
            setSize (200,300);
            setVisible(true);

          }// start()

       }// class ListAddPerfTest


        
      /****************************************************
       Standard Test Machinery
       DO NOT modify anything below -- it's a standard
        chunk of code whose purpose is to make user
        interaction uniform, and thereby make it simpler
        to read and understand someone else's test.
       ****************************************************/

      /**
       This is part of the standard test machinery.
       It creates a dialog (with the instructions), and is the interface
        for sending text messages to the user.
       To print the instructions, send an array of strings to Sysout.createDialog
        WithInstructions method. Put one line of instructions per array entry.
       To display a message for the tester to see, simply call Sysout.println
        with the string to be displayed.
       This mimics System.out.println but works within the test harness as well
        as standalone.
       */

      class Sysout
       {
         private static TestDialog dialog;

         public static void createDialogWithInstructions( String[] instructions )
          {
            dialog = new TestDialog( new Frame(), "Instructions" );
            dialog.printInstructions( instructions );
            dialog.show();
            println( "Any messages for the tester will display here." );
          }
         
         public static void createDialog( )
          {
            dialog = new TestDialog( new Frame(), "Instructions" );
            String[] defInstr = { "Instructions will appear here. ", "" } ;
            dialog.printInstructions( defInstr );
            dialog.show();
            println( "Any messages for the tester will display here." );
          }
         
            
         public static void printInstructions( String[] instructions )
          {
            dialog.printInstructions( instructions );
          }


         public static void println( String messageIn )
          {
            dialog.displayMessage( messageIn );
          }

       }// Sysout class

      /**
        This is part of the standard test machinery. It provides a place for the
         test instructions to be displayed, and a place for interactive messages
         to the user to be displayed.
        To have the test instructions displayed, see Sysout.
        To have a message to the user be displayed, see Sysout.
        Do not call anything in this dialog directly.
        */
      class TestDialog extends Dialog
       {

         TextArea instructionsText;
         TextArea messageText;
         int maxStringLength = 80;
         
         //DO NOT call this directly, go through Sysout
         public TestDialog( Frame frame, String name )
          {
            super( frame, name );
            int scrollBoth = TextArea.SCROLLBARS_BOTH;
            instructionsText = new TextArea( "", 15, maxStringLength, scrollBoth );
            add( "North", instructionsText );
            
            messageText = new TextArea( "", 5, maxStringLength, scrollBoth );
            add("South", messageText);
            
            pack();
            show();
          }// TestDialog()

         //DO NOT call this directly, go through Sysout
         public void printInstructions( String[] instructions )
          {
            //Clear out any current instructions
            instructionsText.setText( "" );

            //Go down array of instruction strings

            String printStr, remainingStr;
            for( int i=0; i < instructions.length; i++ )
             {
               //chop up each into pieces maxSringLength long
               remainingStr = instructions[ i ];
               while( remainingStr.length() > 0 )
                {
                  //if longer than max then chop off first max chars to print
                  if( remainingStr.length() >= maxStringLength )
                   {
                     //Try to chop on a word boundary
                     int posOfSpace = remainingStr.
                        lastIndexOf( ' ', maxStringLength - 1 );
                     
                     if( posOfSpace <= 0 ) posOfSpace = maxStringLength - 1;
                                    
                     printStr = remainingStr.substring( 0, posOfSpace + 1 );
                     remainingStr = remainingStr.substring( posOfSpace + 1 );
                   }
                  //else just print
                  else
                   {
                     printStr = remainingStr;
                     remainingStr = "";
                   }
                  
                  instructionsText.append( printStr + "\n" );
                  
                }// while
               
             }// for
            
          }//printInstructions()

         //DO NOT call this directly, go through Sysout
         public void displayMessage( String messageIn )
          {
            messageText.append( messageIn + "\n" );
          }
         
       }// TestDialog class
        

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            • Assignee:
              ehawkessunw Eric Hawkes (Inactive)
              Reporter:
              ehawkessunw Eric Hawkes (Inactive)
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              • Created:
                Updated:
                Resolved:
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