Java实现简易计算器

import java.awt.*;
import java.awt.event.*;
public class Main extends Frame implements ActionListener{
private MenuBar mbr;
private Button b1,b2,b3,b4,b5,b6,b7,b8,b9,b0,b11,b12,b13,b14,b15,b16;
private Label ta;
private double sum=0;
private String str = "0";
private String res = "";
private String q1 = "";
private String q2 = "";
public Main()
{
super("计算器");
b1=new Button("1");
b2=new Button("2");
b3=new Button("3");
b4=new Button("4");
b5=new Button("5");
b6=new Button("6");
b7=new Button("7");
b8=new Button("8");
b9=new Button("9");
b0=new Button("0");
b11=new Button("=");
b12=new Button("-");
b13=new Button("/");
b14=new Button("*");
b15=new Button("+");
b16=new Button("C");
b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
b4.addActionListener(this);
b5.addActionListener(this);
b6.addActionListener(this);
b7.addActionListener(this);
b8.addActionListener(this);
b9.addActionListener(this);
b0.addActionListener(this);
b11.addActionListener(this);
b12.addActionListener(this);
b13.addActionListener(this);
b14.addActionListener(this);
b15.addActionListener(this);
ta=new Label(str,Label.RIGHT);
add(b1);
add(b2);
add(b3);
add(b4);
add(b5);
add(b6);
add(b7);
add(b8);
add(b9);
add(b0);
add(b11);
add(b12);
add(b13);
add(b14);
add(b15);
add(b16);
add(ta);
b16.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
ta.setText("");
}
});
setLayout(null);
ta.setBounds(0,30,200,100);
b7.setBounds(0,100,50,50);
b8.setBounds(50,100,50,50);
b9.setBounds(100,100,50,50);
b13.setBounds(150,100,50,50);
b4.setBounds(0,150,50,50);
b5.setBounds(50,150,50,50);
b6.setBounds(100,150,50,50);
b14.setBounds(150,150,50,50);
b1.setBounds(0,200,50,50);
b2.setBounds(50,200,50,50);
b3.setBounds(100,200,50,50);
b12.setBounds(150,200,50,50);
b0.setBounds(0,250,50,50);
b16.setBounds(50,250,50,50);
b11.setBounds(100,250,50,50);
b15.setBounds(150,250,50,50);

addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent we)
{
System.exit(0);
}
});

this.setSize(202,300);
this.setLocationRelativeTo(null);
this.setResizable(false);
this.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
double x=0;
double ans=0;
String str=e.getActionCommand();
if(str.equals("1")||str.equals("2")||str.equals("3")||str.equals("4")||str.equals("5")||str.equals("6")||str.equals("7")||str.equals("8")||str.equals("9")||str.equals("0"))
{
res = res+str;
ta.setText(res);
}
else if(str.equals("+")||str.equals("-")||str.equals("*")||str.equals("/")||str.equals("="))
{
q2 = str;
if (q1.equals(""))
{
x = Double.parseDouble(ta.getText());
sum += x;
res = "";
q1 = q2;
}
else if(q1.equals("+"))
{
ans = Double.parseDouble(ta.getText());
sum += ans;
ta.setText(""+sum);
res = "";
q1 = q2;
}
else if(q1.equals("-"))
{
ans = Double.parseDouble(ta.getText());
sum -= ans;
ta.setText(""+sum);
res = "";
q1 = q2;
}
else if(q1.equals("*"))
{
ans = Double.parseDouble(ta.getText());
sum *= ans;
ta.setText(""+sum);
res = "";
q1 = q2;
}
else if(q1.equals("/"))
{
ans = Double.parseDouble(ta.getText());
sum /= ans;
ta.setText(""+sum);
res = "";
q1 = q2;
}
else if(q1.equals("="))
{
ans = Double.parseDouble(ta.getText());
sum = ans;
ta.setText(""+sum);
q1 = q2;
}
}
}
public static void main(String args[])
{
new Main();
}
}