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Reading Directories and Files in Java

Posted on 2004-08-10
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Last Modified: 2012-08-14
I have a combo box control in Java with a first element of "NEW". When i pull down the combo box menu it should display the files  listed in a directory under windows. I should be able to open the file that I select and display the contents to a List Box. If I select "NEW" it should clear the contents of the List Box.

I need some code samples that I can try, which is the reason for the high points. If you've done this before or know where to get some code samples please provide information and I will award the points.

thanks
GS
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Question by:GoldStrike
  • 4
7 Comments
 
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Accepted Solution

by:
sudhakar_koundinya earned 500 total points
ID: 11765262
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Expert Comment

by:sudhakar_koundinya
ID: 11765630
the following code may helps you to write your further code

import javax.swing.*;
import java.io.*;
/*
 * Created on Aug 10, 2004
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

/**
 * @author Sudhakar
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
public class AddFiles extends JFrame {
      
      JComboBox combo=new JComboBox();
      public AddFiles()
      {
            init();
      }
      public void init()
      {
            addFiles(combo,"c:/");
            JPanel pane=new JPanel();
            pane.add(combo);
            this.getContentPane().add(pane);
      }
      public static void main(String s[])
      {
            AddFiles files=new AddFiles();
            files.setSize( 400,300);
            files.show() ;
      }
      public void addFiles(JComboBox _combo,String file)
      {
            File dir = new File(file);
          
          String[] children = dir.list();
          if (children == null) {
              // Either dir does not exist or is not a directory
          } else {
              for (int i=0; i<children.length; i++) {
                  // Get filename of file or directory
                  String filename = children[i];
                  _combo.addItem(filename );
              }
          }

      }

}
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Expert Comment

by:sudhakar_koundinya
ID: 11766035
and this is ur combo listener class
class MyActionListener implements ActionListener {
                public void actionPerformed(ActionEvent ae)
      {       
                      if(ae.getSource() ==combo)
             {
                   JComboBox cb = (JComboBox)ae.getSource();
                   Object newItem = cb.getSelectedItem();
                   try
                  {
                         FileInputStream fin=new FileInputStream(newItem.toString());
                         File file=new File(newItem.toString());
                         int length=(int)file.length();
                         byte bytes[]=new byte[length];
                         fin.read(bytes);
                         String string=new String(bytes);
                         String[] lines=string.split( "\n");
                         for(int i=0;i<lines.length;i++)
                         {
                               list.add(lines[i],null);
                               System.err.println(lines[i]);
                         }
                         
                  }
                   catch(Exception ex)
                  {
                               
                     }
             }
       }
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LVL 1

Expert Comment

by:jmeree
ID: 11768425
Why not use a JFileChooser like this? (created with netbeans)

import java.io.BufferedReader;
import javax.swing.JFileChooser;

public class FileViewer extends javax.swing.JFrame {
   
    private javax.swing.JButton exitButton;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JPanel jPanel3;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JButton newButton;
    private javax.swing.JButton openButton;
   
    public FileViewer() {
        super("File Viewer");
        initComponents();
    }
   
    private void initComponents() {
        jPanel1 = new javax.swing.JPanel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jPanel2 = new javax.swing.JPanel();
        jPanel3 = new javax.swing.JPanel();
        openButton = new javax.swing.JButton();
        newButton = new javax.swing.JButton();
        exitButton = new javax.swing.JButton();

        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowClosing(java.awt.event.WindowEvent evt) {
                exitForm(evt);
            }
        });

        jTextArea1.setPreferredSize(new java.awt.Dimension(300, 300));
        jScrollPane1.setViewportView(jTextArea1);

        jPanel1.add(jScrollPane1);

        getContentPane().add(jPanel1, java.awt.BorderLayout.CENTER);

        getContentPane().add(jPanel2, java.awt.BorderLayout.NORTH);

        openButton.setLabel("Open");
        openButton.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                openButtonMouseClicked(evt);
            }
        });

        jPanel3.add(openButton);

        newButton.setLabel("New");
        newButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                newButtonActionPerformed(evt);
            }
        });
        jPanel3.add(newButton);

        exitButton.setLabel("Exit");
        exitButton.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                exitButtonMouseClicked(evt);
            }
        });

        jPanel3.add(exitButton);

        getContentPane().add(jPanel3, java.awt.BorderLayout.SOUTH);

        pack();
    }

    private void exitButtonMouseClicked(java.awt.event.MouseEvent evt) {
        System.exit (0) ;
    }

    private void openButtonMouseClicked(java.awt.event.MouseEvent evt) {
        JFileChooser chooser = new JFileChooser();
        int returnVal = chooser.showOpenDialog(this);
        if(returnVal == JFileChooser.APPROVE_OPTION) {
           java.io.File f = chooser.getSelectedFile();
           System.out.println("You chose to open this file: " + f.getAbsolutePath() );
           try {
               BufferedReader br = new BufferedReader ( new java.io.FileReader(f) );
               String tempLine = null ;
               jTextArea1.setText(null);
               while( ( tempLine = br.readLine() ) != null ) { jTextArea1.append( tempLine + "\n" );  }
           }
           catch ( java.io.FileNotFoundException e ) {
              e.printStackTrace();
              System.exit (-1);
           }
           catch ( java.io.IOException e ) {
              e.printStackTrace();
              System.exit (-1);
           }
        }
    }

    private void newButtonActionPerformed(java.awt.event.ActionEvent evt) {
        jTextArea1.setText(null);
    }
   
    /** Exit the Application */
    private void exitForm(java.awt.event.WindowEvent evt) {
        System.exit(0);
    }
   
    public static void main(String args[]) {
        new FileViewer().show();
    }
   
}
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Author Comment

by:GoldStrike
ID: 11882016
thanks for all the inputs, I apologize for being late. The GetFiles and Add Items answered my questions.
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LVL 14

Expert Comment

by:sudhakar_koundinya
ID: 11883700
:-)
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