skyyoung:问题已经解决,不敢独享(requestFocus)
public void focusGained(FocusEvent e){}
// 失去焦点时,对所输入进行合法性验证
public void focusLost(FocusEvent e)
{ jTextField1.removeFocusListener(this);
str=jTextField1.getText();
if(str==null || "".compareTo(str.trim())==0
{
Toolkit.getDefaultToolkit().beep();
JOptionPane.showMessageDialog(this,"不允许空,请重新输入.");
requestFocus();
}
jTextField1.addFocusListener(this);
}