TextField tf = new TextField ();
//对该文本框进行监听
tf.addFocusListener (new FocusListener(){
// 失去焦点的时候
@Override
public void focusLost(FocusEvent e) {
if(tf.getText.length ==0 || tf.getText.equals("")){
JOptionPane.showMessageDialog(tf, "请输入文本", "提示",
JOptionPane.YES_OPTION);
}
}
@Override
public void focusGained(FocusEvent e) {
}
});
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