bear102 wrote:
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.lang.*;
public class AppletSum extends JApplet
{
implementors ActionListener; //这里有问题，看看语法书，是这么写的吗？应该放到extends JApplet后面
{
JTextField inputOen=new JTextField(20);
JTextField inputTwo=new JTextField(20);
JTextField output=new JTextField(20);
public void init()
{
Container pane=getContentPane();
pane.setLayout(new FlowLayout());
pane.add(new JLabel("Enter one number."));
pane.add(inputOne);
pane.add(new JLabel("Enter a number and hit retun."));
pane.add(inputTwo);
pane.add(new JLabel("Thier sum is:"));
pane.add(output);
inputTwo.addActionListenter(this);
}
public void actionPerformed(ActionEvent e)
{
double first,second,sum;
first=Double.parseDouble(inputOne.getText());
second=Double.parseDouble(inputTwo.getText());
sum=first+second;
output.setText(String.valueof(sum));
} ;
}
}
编译后出现如下错误：

Appletsum.java:13: 非法的表达式开始

public void init()
^
一个错误