final JTextField jtfContent = new JTextField();
btnOK.addActionListener(new java.awt.event.ActionListener(){
public void actionPerformed(java.awt.event.ActionEvent event){
jtfContent.setText("I am OK");
}
} );
如果我省略 final
,我会看到错误 "Cannot refer to a non-final variable jtfContent inside an inner class defined in a different method"。
为什么匿名内部类要求外部类的实例变量必须是 final 才能访问它?