Question

java 文本框的小问题

JButton b4=new JButton();
String text1,text2;
JTextArea t1=new JTextArea();
JTextArea t2=new JTextArea();
text1=t1.getText();
text2=t2.getText();
b4.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
t1.append(text2);
t2.repaint();
}
}
);

我想在单击b4后，把文本区t2 的文本添加到文本区t1里，t2清空，应怎么改？
t1，t2，text2下面画红色波浪线，应该有错吧！我怎么看不出有什么错误？

编译提示：
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
Cannot refer to a non-final variable t1 inside an inner class defined in a different method
Cannot refer to a non-final variable text2 inside an inner class defined in a different method
Cannot refer to a non-final variable t2 inside an inner class defined in a different method

at QQ.main(QQ.java:106)

Answer 1

因为实在内部类中调用t1,t2所以应当声明为final
改为：
final JTextArea t1=new JTextArea();
final JTextArea t2=new JTextArea();

t2.repaint();改为t2.setText("");

Answer 2

public void actionPerformed(ActionEvent e)
{
t1.append(text2);
t2.repaint();//改为t2.setText("");
}