方法声明无效；需要返回类型,详细请见下面?

来源：百度知道 编辑：UC知道 时间：2024/06/16 07:41:41
import java.awt.*;
import java.event.*;
public class squre
{

public static void main(String[] args)
{
new AppFrame();

}

class AppFrame extends Frame
{

TextField in = new TextField(10);
Button btn = new Button("求平方");
lable out =new lable("用于显示结果的标签");

}
public AppFrame()

{
setLayout(new FlowLayout());
add(in);
add(btn);
add(out);
btn.addActionListenter(new BtnActionAdapter());
setSize(400,100);
show();

}
class BtnActionAdapter implements ActionLisetener
{
public void actionperformed(ActionEvent e )
{
String s = in .getText();
double d = Double.parseDouble(s);
double sq = d*d;
out.setTExt(d+"的平方是"+sq);
}
}
}

错误太多就不解释了：

import java.awt.Button;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Label;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class squre extends Frame {
public static void main(String[] args) {
new squre();
}

TextField in = new TextField(10);
Button btn = new Button("求平方");
Label out = new Label("用于显示结果的标签");

public squre() {
setLayout(new FlowLayout());
add(in);
add(btn);
add(out);
btn.addActionListener(new BtnActionAdapter());
setSize(400, 100);
setVisible(true);
}

class BtnActionAdapter implements ActionListener {
public void actionPerformed(ActionEvent e) {
String s = in.getText();
double d = Double.parseDouble(s);
double sq = d * d;
out.setText(d + "的平方是&