Question

JTextField 键盘监听事件

编了一段代码 txtTransNumber是我的JTextField，TransNumber是我想要在JTextField上显示的值 但是我每次在输入a~z的时候第一次总是会有字符出现后面就不出现还有删除时也是第一下删掉两个值，请问该怎么解决主要是不要显示出字符。
txtTransNumber.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent event) {
if (event.getKeyCode() > KeyEvent.VK_9
| event.getKeyCode() < KeyEvent.VK_0) {
switch (event.getKeyCode()) {
case KeyEvent.VK_BACK_SPACE:
{
TransNumber = TransNumber.substring(0, TransNumber.length() - 1);
FrmTransNumber.this.txtTransNumber.setText(TransNumber);
}
break;
case KeyEvent.VK_ESCAPE: {
TransNumber = "";
FrmTransNumber.this.setVisible(false);
break;
}
case KeyEvent.VK_ENTER: {
TransNumber = FrmTransNumber.this.txtTransNumber.getText();
FrmTransNumber.this.setVisible(false);
break;
}
default: {
FrmTransNumber.this.txtTransNumber.setText(TransNumber);
TransNumber = TransNumber;
}
}
} else {
FrmTransNumber.this.txtTransNumber.setText(TransNumber);
TransNumber = TransNumber+ (char) event.getKeyCode();
}
}
});

Answer 1

public class FrmTransNumber extends JFrame implements KeyListener{

public JTextField txtTransNumber;
public String TransNumber;

public FrmTransNumber(){
txtTransNumber = new JTextField();
this.add(txtTransNumber,BorderLayout.NORTH);
this.addKeyListener(this);
this.setSize(300,300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);

}

public static void main(String[] args) {
FrmTransNumber t = new FrmTransNumber();
}
@Override
public void keyPressed(KeyEvent event) {
if (event.getKeyCode() > KeyEvent.VK_9
| event.getKeyCode() < KeyEvent.VK_0) {
switch (event.getKeyCode()) {
case KeyEvent.VK_BACK_SPACE:
{
TransNumber = TransNumber.substring(0, TransNumber.length() - 1);
FrmTransNumber.this.txtTransNumber.setText(TransNumber);
}
break;
case KeyEvent.VK_ESCAPE: {
TransNumber = "";
FrmTransNumber.this.setVisible(false);
break;
}
case KeyEvent.VK_ENTER: {
TransNumber = FrmTransNumber.this.txtTransNumber.getText();
FrmTransNumber.this.setVisible(false);
break;
}
default: {
FrmTransNumber.this.txtTransNumber.setText(TransNumber);
TransNumber = TransNumber;
}
}
} else {
FrmTransNumber.this.txtTransNumber.setText(TransNumber);
TransNumber = TransNumber+ (char) event.getKeyCode();
}

}
public void keyReleased(KeyEvent e) {

}
public void keyTyped(KeyEvent e) {

}
}
是不是想要这样的效果

追问

输入字符后还是会在屏幕上显示啊。