jf.addFocusListener(new FocusListener()
{
public void focusLost(FocusEvent arg0){
JOptionPane.showMessageDialog(null,"含有非法字符,请重新输入")
}
public void focusGained(FocusEvent arg0){
}
})
如果还不太清楚HI我吧
Java编码中焦点改变问题,做个登陆界面案例,输入用户名的是JCombobox;输入密码是JPasswordText;当软件启动的时候,让光标焦点默认在密码输入框内代码如下:
import java.awt.*import javax.swing.*
public class requestFocusLnWindowDemo extends JFrame{
public requestFocusLnWindowDemo() {
Container c = this.getContentPane()
c.setLayout(new BorderLayout())
JTextField j = new JTextField("希望光标在下面",10)
final JTextField j1 = new JTextField(10)
c.add(j,BorderLayout.NORTH)
c.add(j1,BorderLayout.SOUTH)
this.setSize(300,200)
this.setLocationRelativeTo(null)//这句可以使窗口在屏幕中间显示
this.setVisible(true)
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
SwingUtilities.invokeLater(new Runnable(){
public void run(){
j1.requestFocusInWindow()
}
})
}
public static void main(String []args){
new requestFocusLnWindowDemo()
}
}