java 简易计算器代码

demo1：

import java.awt.*;
import java.awt.event.*;
public class num implements ActionListener
{
Frame win=new Frame("jiandanjisuanqi");
Panel num=new Panel();
Panel meth = new Panel();
TextArea display=new TextArea();
Button add1,sub,mul,div;
int no1,no2;
float no3;
String ch,ch3;
Button res=new Button("=");
Button canc=new Button("CE");
Button but7=new Button("7");
Button but8=new Button("8");
Button but9=new Button("9");
Button but4=new Button("4");
Button but5=new Button("5");
Button but6=new Button("6");
Button but1=new Button("1");
Button but2=new Button("2");
Button but3=new Button("3");
Button but0=new Button("0");
public void test()
{
add1=new Button("+");
sub=new Button("-");
mul=new Button("*");
div=new Button("/");
win.setLayout(new GridLayout(4,0));
num.setLayout(new GridLayout(4,4));
num.add(but7);
num.add(but8);
num.add(but9);
num.add(add1);
num.add(but4);
num.add(but5);
num.add(but6);
num.add(sub);
num.add(but1);
num.add(but2);
num.add(but3);
num.add(mul);
num.add(but0);
num.add(canc);
num.add(res);
num.add(div);
but0.addActionListener(this);
but1.addActionListener(this);
but2.addActionListener(this);
but3.addActionListener(this);
but4.addActionListener(this);
but5.addActionListener(this);
but6.addActionListener(this);
but7.addActionListener(this);
but8.addActionListener(this);
but9.addActionListener(this);
canc.addActionListener(new CE());
add1.addActionListener(new METH());
sub.addActionListener(new METH());
mul.addActionListener(new METH());
div.addActionListener(new METH());
res.addActionListener(new RES());
win.add(display);
win.add(num);
win.setSize(400,400);
//win.setBackground(Color.black);
win.setForeground(Color.red);
win.setVisible(true);
win.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
}
public void actionPerformed(ActionEvent e)
{
display.append(e.getActionCommand());
}
private class CE implements ActionListener
{
public void actionPerformed(ActionEvent ex)
{
display.setText("");
no1=0;
no2=0;
no3=0;
}
}
private class METH implements ActionListener
{
public void actionPerformed(ActionEvent ey)
{
no1=Integer.parseInt(display.getText());
display.setText("");
ch=ey.getActionCommand();
}
}
private class RES implements ActionListener
{
public void actionPerformed(ActionEvent es)
{
no2=Integer.parseInt(display.getText());
if(ch=="+")
{
no3=no1+no2;
ch3=Float.toString(no3);
display.setText(ch3);
}
else if(ch=="-")
{
no3=no1-no2;
ch3=Float.toString(no3);
display.setText(ch3);
}
else if(ch=="*")
{
no3=no1*no2;
ch3=Float.toString(no3);
display.setText(ch3);
}
else if(ch=="/")
{
no3=(float)no1/no2;
ch3=Float.toString(no3);
display.setText(ch3);
if(no2==0){
display.setText("");
}
}
}
}
public static void main (String[]args)
{
num s=new num();
s.test();
}
}

/*public class num{
public static void main(String[] arge){
System.out.print(switchIt(2));

}
public static int switchIt(int x){
int j=1;
switch (x) {
case 1:j++;
case 2:j++;
case 3:j++;

default: j++;
break;
}
return j+x;
}
}*/


demo2;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Calculator extends WindowAdapter implements ActionListener {
JFrame list;
JTextField show;
JButton bc, c, ce, ab, jia, jian, cheng, chu, equ, point, sqrt, ds, bfh, zf;
// 按钮 退格，清空，复位，关于，加，减，乘，除，等号，小数点，2次方根，倒数，百分号，正负号
JButton b[] = new JButton[10]; // 按钮数组，数字键0～9
double sum = 0, getValue;
int i = 0, j = 0, p = 0, l, action;
JDialog about;
final int slength = 30; // 设置结果显示有效长度

public void disp() {
list = new JFrame("简易计算器");
list.setSize(360, 230);
list.setLocation(380, 260);
list.setBackground(Color.LIGHT_GRAY);
list.setLayout(new FlowLayout(FlowLayout.CENTER));
list.setResizable(false);
show = new JTextField(31);
show.setText("0");
show.setHorizontalAlignment(SwingConstants.RIGHT);
show.setEditable(false);
list.add(show);

Panel dispTop = new Panel();
list.add(dispTop);
dispTop.setLayout(new GridLayout(1, 4, 3, 3));
bc = new JButton(" Back ");
bc.setForeground(Color.BLUE);
dispTop.add(bc);
ce = new JButton(" CE ");
ce.setForeground(Color.BLUE);
dispTop.add(ce);
c = new JButton(" C ");
c.setForeground(Color.BLUE);
dispTop.add(c);
ab = new JButton(" About ");
ab.setForeground(Color.BLUE);
dispTop.add(ab);
about = new JDialog(list, "关于计算器", true);
Label ct = new Label("hello world!", 1);
ct.setForeground(Color.RED);
about.add(ct, "Center");
about.setSize(200, 100);
about.setLocation(500, 300);
about.addWindowListener(this);

Panel dispMain = new Panel();
list.add(dispMain);
dispMain.setLayout(new GridLayout(1, 2, 10, 10));

Panel dispLeft = new Panel();
dispMain.add(dispLeft);
dispLeft.setLayout(new GridLayout(4, 3, 3, 3));

Panel dispRight = new Panel();
dispMain.add(dispRight);
dispRight.setLayout(new GridLayout(4, 2, 3, 3));
for (l = 9; l >= 0; l--) {
b[l] = new JButton(String.valueOf(l));
dispLeft.add(b[l]);
b[l].addActionListener(this);
}
jia = new JButton("+");
jia.setForeground(Color.RED);
jian = new JButton("-");
jian.setForeground(Color.RED);
cheng = new JButton("*");
cheng.setForeground(Color.RED);
chu = new JButton("/");
chu.setForeground(Color.RED);
equ = new JButton("=");
equ.setForeground(Color.RED);
point = new JButton(".");
zf = new JButton(" +/- ");
sqrt = new JButton("sqrt");
bfh = new JButton("%");
ds = new JButton("1/x");
dispRight.add(chu);
dispRight.add(sqrt);
dispRight.add(cheng);
dispRight.add(bfh);
dispRight.add(jian);
dispRight.add(ds);
dispRight.add(jia);
dispRight.add(equ);
dispLeft.add(zf);
dispLeft.add(point);
bc.addActionListener(this);
ce.addActionListener(this);
c.addActionListener(this);
ab.addActionListener(this);
jia.addActionListener(this);
jian.addActionListener(this);
cheng.addActionListener(this);
chu.addActionListener(this);
equ.addActionListener(this);
point.addActionListener(this);
zf.addActionListener(this);
sqrt.addActionListener(this);
bfh.addActionListener(this);
ds.addActionListener(this);
list.addWindowListener(this);
list.setVisible(true);
}

public void actionPerformed(ActionEvent e) {
getValue = Double.valueOf(show.getText()).doubleValue();
// getValue=Double.valueOf(show.getText());//如果该行出错，则在后面加上.doubleValue();属版本兼容问题
if (e.getSource() == jia) { // 加运算，可连加
if (j == 0) {
sum = getValue;
} else if (action == 1) {
sum += getValue;
}
setSum();
j++;
p = 0;
i = 0;
action = 1;
} else if (e.getSource() == jian) { // 减运算，可连减
if (j == 0) {
sum = getValue;
} else if (action == 2) {
sum -= getValue;
}
setSum();
j++;
p = 0;
i = 0;
action = 2;
} else if (e.getSource() == cheng) { // 乘运算，可连乘
if (j == 0) {
sum = getValue;
} else if (action == 3) {
sum *= getValue;
}
setSum();
j++;
p = 0;
i = 0;
action = 3;
} else if (e.getSource() == chu) { // 除运算，可连除
if (j == 0)
sum = getValue;
else if (action == 4) {
sum /= getValue;
}
setSum();
j++;
p = 0;
i = 0;
action = 4;
} else if (e.getSource() == equ) { // 等号,运算最后一个操作数
switch (action) {
case 1:
show.setText(String.valueOf(sum += getValue));
break;
case 2:
show.setText(String.valueOf(sum -= getValue));
break;
case 3:
show.setText(String.valueOf(sum *= getValue));
break;
case 4:
show.setText(String.valueOf(sum /= getValue));
break;
}
setSum();
i = 0;
j = 0;
action = 0;
} else if (e.getSource() == point) { // 小数点,只能按一个小数点
if (p == 0)
show.setText(show.getText() + e.getActionCommand());
p = 1;
} else if (e.getSource() == c || e.getSource() == ce) { // 清空与复位
i = 0;
j = 0;
p = 0;
sum = 0;
action = 0;
show.setText("0");
} else if (e.getSource() == bc) { // 退格
String s = show.getText();
if (s.length() > 1) {
show.setText("");
for (l = 0; l < s.length() - 1; l++) { // 按一下,删除尾部一位
char a = s.charAt(l);
show.setText(show.getText() + a);
}
} else
show.setText("0");
} else if (e.getSource() == ab) { // 关于
about.setVisible(true);
} else if (e.getSource() == sqrt) { // 开2次方根
sum = Math.sqrt(getValue);
setSum();
j++;
} else if (e.getSource() == ds) { // 求倒数
sum = 1 / getValue;
setSum();
j++;
} else if (e.getSource() == bfh) { // 百分号
sum = getValue / 100;
setSum();
j++;
} else if (e.getSource() == zf) { // 正负号切换,正号不显示
String s = show.getText();
char a = s.charAt(0);
if (a == '-') {
show.setText("");
for (l = 1; l < s.length(); l++) { // 去掉负号
show.setText(show.getText() + s.charAt(l));
}
} else if (getValue != 0) { // 加上负号
show.setText("-" + s);
}
}
for (l = 0; l < 10; l++) { // 0~9数字键触发
if (e.getSource() == b[l]) {
if (i == 0)
show.setText("");
String s = show.getText();
if (s.length() < slength)
show.setText(show.getText() + e.getActionCommand());
if (e.getSource() == b[0] && getValue == 0 && p == 0)
show.setText("0");
if (e.getSource() != b[0] && getValue == 0 && p == 0)
show.setText(e.getActionCommand());
i++;
}
}
}

public void setSum() { // 把计算结果显示出来
show.setText(String.valueOf(sum));
String s = show.getText();
char a = s.charAt((s.length() - 1));
char b = s.charAt((s.length() - 2));
if (a == '0' && b == '.') { // 如果是整数,则去掉后面的小数点和0
show.setText(String.valueOf(Math.round(sum)));
}
}

public void windowClosing(WindowEvent e) {
if (e.getSource() == about)
about.setVisible(false);
else if (e.getSource() == list)
System.exit(0);
}

public static void main(String args[]) {
(new Calculator()).disp();
}
}