弹出JDialog,为什么不能响应输入数字

Question

用了两个简单的类Frame0618.java和TargetDialog.java来试验.老是提示出错:
Exception occurred during event dispatching:
java.lang.NullPointerException
        at worldwind.TargetDialog.jButton1ActionPerformed(TargetDialog.java:112)
        at worldwind.TargetDialog.access$000(TargetDialog.java:19)
        at worldwind.TargetDialog$1.actionPerformed(TargetDialog.java:51)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
源代码:第一个类如下
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */package worldwind;import java.awt.Component;
import java.awt.Event;
import java.awt.Frame;
import java.awt.event.InputEvent;
import javax.swing.JOptionPane;
import javax.swing.JPopupMenu;/**
 *
 * @author Administrator
 */
public class Frame0618 extends Frame{
    static int geju=50,geshu=11;
    static Frame0618 frm = new Frame0618();
    static ChessPanel2 chesspanel = new ChessPanel2(geju,geshu);
    JPopupMenu popup=new JPopupMenu();
    TargetDialog dlg = new TargetDialog(frm,true);
    static double[][] target_xyz;//    class onrbutttondown implements MouseListener {
//
//        public void mouseClicked(MouseEvent e) {
//            System.out.println("xulei!!!!!");
//        }
//
//        public void mousePressed(MouseEvent e) {
//            throw new UnsupportedOperationException("Not supported yet.");
//        }
//
//        public void mouseReleased(MouseEvent e) {
//            throw new UnsupportedOperationException("Not supported yet.");
//        }
//
//        public void mouseEntered(MouseEvent e) {
//            throw new UnsupportedOperationException("Not supported yet.");
//        }
//
//        public void mouseExited(MouseEvent e) {
//            throw new UnsupportedOperationException("Not supported yet.");
//        }
//    }
/*@Override
    public boolean mouseDown(Event evt,int x,int y){
    System.out.println("hello!xulei!!!");
    return true;
    }*/
    @Override
    public boolean mouseDown(Event e,int x,int y) {
        //this.add(jPopupMenu1);
       int mods = e.modifiers;//左键时mods是0,右键时是4        if ((mods & InputEvent.BUTTON3_MASK) != 0) {
            
            //dlg.setVisible(true);
//            String s = javax.swing.JOptionPane.showInputDialog(this,"message","target_time",2);
//            target_xyz[0][3] = Double.valueOf(s).doubleValue();
//            System.out.println(target_xyz[0][3]);
            //System.out.println("当前鼠标坐标是"+x+"; "+y+"; ");
            dlg.setVisible(true);
            if(dlg.isModal()){
                System.out.println("当前");
//                target_xyz[0][3]=((Number)dlg.targetTime.getValue()).doubleValue();
            }        }
        return true;
    }
    
    public static void main(String[] args ) {        frm.setSize(800,800);
        frm.add(chesspanel);
        //frm.addMouseListener(l);
        frm.setVisible(true);
    }
}
第二个类如下/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 *//*
 * TargetDialog.java
 *
 * Created on 2009-6-19, 11:13:08
 */package worldwind;/**
 *
 * @author Administrator
 */public class TargetDialog extends javax.swing.JDialog {    int time ;
    /** Creates new form TargetDialog */
    public TargetDialog(java.awt.Frame parent, boolean modal) {
        super(parent, modal);
        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.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {
        bindingGroup = new org.jdesktop.beansbinding.BindingGroup();        jLabel1 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        targetTime = new javax.swing.JFormattedTextField();        org.jdesktop.beansbinding.Binding binding = org.jdesktop.beansbinding.Bindings.createAutoBinding(org.jdesktop.beansbinding.AutoBinding.UpdateStrategy.READ_WRITE, this, org.jdesktop.beansbinding.ELProperty.create("${defaultCloseOperation}"), this, org.jdesktop.beansbinding.BeanProperty.create("defaultCloseOperation"));
        bindingGroup.addBinding(binding);        jLabel1.setText("停留时间");        jButton1.setText("OK");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });        jButton2.setText("Cancel");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });        targetTime.setText("0");
        targetTime.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                targetTimeActionPerformed(evt);
            }
        });        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(38, 38, 38)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                    .addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jLabel1, javax.swing.GroupLayout.DEFAULT_SIZE, 71, Short.MAX_VALUE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jButton2)
                    .addComponent(targetTime, javax.swing.GroupLayout.PREFERRED_SIZE, 105, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap(37, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(50, 50, 50)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 42, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(targetTime, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(41, 41, 41)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton2))
                .addContainerGap(41, Short.MAX_VALUE))
        );        bindingGroup.bind();        pack();
    }// </editor-fold>                            private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
    }                                            private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        //WWJFrame.m_target_position1 = ((Number)this.targetTime.getValue()).doubleValue();
        //Frame0618.target_xyz[0][3]=((Number)this.targetTime.getValue()).doubleValue();
        
        System.out.println(((Number)this.targetTime.getValue()).doubleValue());
    }                                            private void targetTimeActionPerformed(java.awt.event.ActionEvent evt) {                                           
        // TODO add your handling code here:
    }                                              /**
    * @param args the command line arguments
    */
    /*public static void main(String args[]) {
    java.awt.EventQueue.invokeLater(new Runnable() {
    public void run() {
    TargetDialog dialog = new TargetDialog(new javax.swing.JFrame(), true);
    dialog.addWindowListener(new java.awt.event.WindowAdapter() {
    public void windowClosing(java.awt.event.WindowEvent e) {
    System.exit(0);
    }
    });
    dialog.setVisible(true);
    }
    });
    }*/    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JLabel jLabel1;
    protected javax.swing.JFormattedTextField targetTime;
    private org.jdesktop.beansbinding.BindingGroup bindingGroup;
    // End of variables declaration                   }以上是所有代码

Answer 1

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                       
        // TODO add your handling code here:
        //WWJFrame.m_target_position1 = ((Number)this.targetTime.getValue()).doubleValue();
        //Frame0618.target_xyz[0][3]=((Number)this.targetTime.getValue()).doubleValue();
       
        System.out.println(((Number)this.targetTime.getValue()).doubleValue());
    }      
上面的这个方法的this.targetTime.getValue()的值为null，这里不知道通过什么可以得到这个输入框的值为Number的。这里的value属性是从来没有设置过的