JAVA GUI学习的小问题 求助各位大大

[ffc19860831]

这是我在听马士兵的视屏是做的练习 可编译的时候老是有问题 找不出来

在线等帮助
import java.awt.*;
import java.awt.event.*;

public class TFMath {
public static void main(String args[]) {
new TFFrame().launchFrame();
}
}

class TFFrame extends Frame {
public void launchFrame() {
TextField num1 = new TextField(10);
TextField num2 = new TextField(10);
TextField num3 = new TextField(15);
Label lbplus = new Label("+");
Button BEqual = new Button("=");
BEqual.addActionListener(new MyMonitor(this));
setLayout(new FlowLayout());
add(num1);
add(lbplus);
add(num2);
add(BEqual);
add(num3);
pack();
setVisible(true);
}
}

class MyMonitor implements ActionListener {
TFFrame tf = null;
TextField num1,num2,num3;
public MyMonitor(TFFrame tf) {
this.tf = tf;
}

public void actionPerformed(ActionEvent e) {
int n1 = Integer.parseInt(tf.num1.getText());
int n2 = Integer.parseInt(tf.num2.getText());
tf.num3.setText("" +(n1+n2));
}
}

[knightzhuwei]

import java.awt.*;
import java.awt.event.*;

public class TFMath {
	public static void main(String args[]) {
		new TFFrame().launchFrame();
	}
}

class TFFrame extends Frame {
	TextField num1, num2, num3;

	public void launchFrame() {
		num1 = new TextField(10);
		num2 = new TextField(10);
		num3 = new TextField(15);
		Label lbplus = new Label("+");
		Button BEqual = new Button("=");
		BEqual.addActionListener(new MyMonitor(this));
		setLayout(new FlowLayout());
		add(num1);
		add(lbplus);
		add(num2);
		add(BEqual);
		add(num3);
		pack();
		setVisible(true);
	}
}

class MyMonitor implements ActionListener {
	TFFrame tf = null;

	public MyMonitor(TFFrame tf) {
		this.tf = tf;
	}

	public void actionPerformed(ActionEvent e) {
		int n1 = Integer.parseInt(tf.num1.getText());
		int n2 = Integer.parseInt(tf.num2.getText());
		tf.num3.setText("" + (n1 + n2));
	}
}

[final_xt]

TextField 要作为类的变量，不能作为方法的变量。。。否则new的时候取不到

[ffc19860831]

谢谢 了解了
只能用于成员变量才能访问是吧

[final_xt]

引用 3 楼 ffc19860831 的回复:

谢谢 了解了
只能用于成员变量才能访问是吧

也不一定，那要看成员变量的访问权限，如果是Private的话，就不可以被外表访问了