@DIV
import javax.swing.JFileChooser;
import java.io.*;
import java.io.File;
import javax.swing.filechooser.FileFilter;
        
public class NewJFrame extends javax.swing.JFrame {
    
    /** Creates new form NewJFrame */
    public NewJFrame() {
        initComponents();
    }
    
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    // <editor-fold defaultstate="collapsed" desc=" Generated Code">//GEN-BEGIN:initComponents
    private void initComponents() {
        jButton1 = new javax.swing.JButton();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jButton1.setText("\u30d5\u30a1\u30a4\u30eb\u3092\u958b\u304f");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                    .add(layout.createSequentialGroup()
                        .add(132, 132, 132)
                        .add(jButton1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 196, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                    .add(layout.createSequentialGroup()
                        .add(40, 40, 40)
                        .add(jScrollPane1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 406, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(22, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(19, 19, 19)
                .add(jButton1)
                .add(22, 22, 22)
                .add(jScrollPane1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 440, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(36, Short.MAX_VALUE))
        );
        pack();
    }// </editor-fold>//GEN-END:initComponents

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_jButton1ActionPerformed
        JFileChooser chooser = new JFileChooser();
        myFileFilter filter = new myFileFilter();

        chooser.setFileFilter(filter);
        int returnVal = chooser.showOpenDialog( null );
        if( returnVal == JFileChooser.APPROVE_OPTION ) {
            try {
                String filePath = chooser.getSelectedFile().getPath();
                BufferedReader inFile = new BufferedReader( new FileReader( filePath ) );

                String line = null;
                String data = "";
                while ( ( line = inFile.readLine() ) != null) {
                        data += line + "\r\n";
                }

                inFile.close();

                jTextArea1.setText(data);

            }
            catch ( Exception e ) {
                    System.out.println( e.getMessage() );
            }

        }
    }//GEN-LAST:event_jButton1ActionPerformed
    
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NewJFrame().setVisible(true);
            }
        });
    }
    
    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JButton jButton1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    // End of variables declaration//GEN-END:variables
    
}


class myFileFilter extends FileFilter {
    public boolean accept(File f) {
        if( f.isDirectory() ) {
            return true;
        }

        String s = f.getName();
        int x = s.lastIndexOf('.');
        if( x < 0 ) {
            return false;
        }

        String extention = s.substring(x+1).toLowerCase();
        if( extention.equals("txt") ) {
            return true;
        }
        if( extention.equals("csv") ) {
            return true;
        }

        return false;
    }
    public String getDescription() {
        return "テキスト"; 
    }
  
}
@END