用java写计算器的代码 java怎么写计算器

求用JAVA实现计算器的代码（可实用的，没语法错误的）

import java.awt.BorderLayout; import java.awt.Color; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JTextField; import javax.swing.border.TitledBorder; //导包 public class Jisuanqi extends JFrame implements ActionListener { //继承JFrame 实现事件监听 private JTextField reasult; private JButton btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9, btn0, btnAC, btnAdd, btnSub, btnReasult, btnD, btnAbout, btnCancel; private boolean add, sub, end, s, c; private String str; private double num1, num2; public Jisuanqi() { //构造属性 JPanel p1 = new JPanel(); JPanel p2 = new JPanel(); JPanel p3 = new JPanel(); TitledBorder tb = new TitledBorder("输出"); tb.setTitleColor(Color.BLUE); //标题边框底端线 设置颜色 btnAbout = new JButton(" 关于 "); btnCancel = new JButton("Cancel"); //两个按钮 btnCancel.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ee) { System.exit(0); } }); //给Cancel添加事件监听 当鼠标点击时 程序结束 btnAbout.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ee) { JOptionPane.showMessageDialog(null, "黄盖！！", "消息", JOptionPane.INFORMATION_MESSAGE); } //给“关于”添加事件监听 当鼠标点击时 弹出对话框 显示黄盖 }); p3.add(btnAbout); p3.add(btnCancel); // JPanel p4=new JPanel(); // JPanel p5=new JPanel(); // reasult.setBorder(tb); reasult = new JTextField("0", 20); reasult.setEditable(false); //设置不能修改 reasult.setHorizontalAlignment(JTextField.RIGHT); // 设置文本的水平对齐方式。 reasult.setForeground(Color.BLUE); //颜色 p1.setBorder(tb); p1.add(reasult); btn0 = new JButton("0"); btn0.addActionListener(this); btn1 = new JButton("1"); btn1.addActionListener(this); btn2 = new JButton("2"); btn2.addActionListener(this); btn3 = new JButton("3"); btn3.addActionListener(this); btn4 = new JButton("4"); btn4.addActionListener(this); btn5 = new JButton("5"); btn5.addActionListener(this); btn6 = new JButton("6"); btn6.addActionListener(this); btn7 = new JButton("7"); btn7.addActionListener(this); btn8 = new JButton("8"); btn8.addActionListener(this); btn9 = new JButton("9"); btn9.addActionListener(this); btnD = new JButton("."); btnD.addActionListener(this); btnD.setForeground(Color.RED); btnAC = new JButton("AC"); btnAC.addActionListener(this); btnAC.setBackground(Color.PINK); btnAdd = new JButton("+"); btnAdd.addActionListener(this); btnAdd.setForeground(Color.BLUE); btnSub = new JButton("—"); btnSub.addActionListener(this); btnSub.setForeground(Color.BLUE); btnReasult = new JButton("="); btnReasult.addActionListener(this); btnReasult.setForeground(Color.RED); //事件监听 + 颜色 p2.add(btn1); p2.add(btn2); p2.add(btn3); p2.add(btn4); p2.add(btn5); p2.add(btn6); p2.add(btn7); p2.add(btn8); p2.add(btn9); p2.add(btn0); p2.add(btnD); p2.add(btnAC); p2.add(btnAdd); p2.add(btnSub); p2.add(btnReasult); //面板上添加按钮 p2.setLayout(new GridLayout(5, 3)); //面板上设置对齐方式 add(p1, BorderLayout.NORTH); add(p2, BorderLayout.CENTER); add(p3, BorderLayout.SOUTH); //将p1 p2 p3 面板对象添加到JFrame } public void num(int i) { String s = null; s = String.valueOf(i); if (end) { // 如果数字输入结束，则将文本框置零，重新输入 reasult.setText("0"); end = false; } if ((reasult.getText()).equals("0")) { // 如果文本框的内容为零，则覆盖文本框的内容 reasult.setText(s); } else { // 如果文本框的内容不为零，则在内容后面添加数字 str = reasult.getText() + s; reasult.setText(str); } }/* * * String s=null; * * s=String.valueOf(i); * * str=reasult.getText()+s; * * reasult.setText(str); * * } */ public void actionPerformed(ActionEvent e) { if (e.getSource() == btn1) num(1); else if (e.getSource() == btn2) num(2); else if (e.getSource() == btn3) num(3); else if (e.getSource() == btn4) num(4); else if (e.getSource() == btn5) num(5); else if (e.getSource() == btn6) num(6); else if (e.getSource() == btn7) num(7); else if (e.getSource() == btn8) num(8); else if (e.getSource() == btn9) num(9); else if (e.getSource() == btn0) num(0); else if (e.getSource() == btnAdd) { sign(1); btnD.setEnabled(true); } else if (e.getSource() == btnSub) { sign(2); btnD.setEnabled(true); } else if (e.getSource() == btnAC) { btnD.setEnabled(true); reasult.setText("0"); } else if (e.getSource() == btnD) { str = reasult.getText(); str += "."; reasult.setText(str); btnD.setEnabled(false); } else if (e.getSource() == btnReasult) { btnD.setEnabled(true); num2 = Double.parseDouble(reasult.getText()); if (add) { num1 = num1 + num2; } else if (sub) { num1 = num1 - num2; } reasult.setText(String.valueOf(num1)); end = true; } } public void sign(int s) { if (s == 1) { add = true; sub = false; } else if (s == 2) { add = false; sub = true; } num1 = Double.parseDouble(reasult.getText()); end = true; } //设计计算的过程 public static void main(String[] args) { Jisuanqi j = new Jisuanqi(); j.setTitle("+/-简易计算器"); j.setLocation(500, 280); j.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //默认关闭可以关闭程序 j.setResizable(false); j.pack(); j.setVisible(true); } } 这个计算机，绝对让你满意

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怎么用JAVA编程编写一个计算器？

打开IED：打开自己java编程的软件，采用的是eclipse软件。

建立java工程。

编写类。

编写类的详细步骤

1.类的基本结构：

由于这里用到了界面，所以要进行窗口界面的编程，按钮事件的处理，和计算处理界面；

package MyCaculator;

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class MyCaculator extends JFrame {

private int add=1,sub=2,mul=3,div=4;

private int op=0;

boolean ifOp;

private String output="0";

private Button[] jba=new Button[]{new Button("7"),new Button("8"),

new Button("9"),new Button("+"),

new Button("4"),new Button("5"),new Button("6"),new Button("-"),

new Button("1"),new Button("2"),new Button("3"),new Button("*"),

new Button("0"),new Button("."),new Button("="),new Button("/")};

private JPanel jpt=new JPanel();

private JPanel jpb=new JPanel();

private JTextField jtf=new JTextField("");

private MyCaculator(){

}

private void operate(String x){

}

public String add(String x){

return output;

}

public String subtract(String x){

return output;

}

public String multiply(String x){

return output;

}

public String divide(String x){

return output;

}

public String Equals(String x){

return output;

}

public void opClean(){

}

class setOperate_Act implements ActionListener{

public void actionPerformed(ActionEvent e) {

}

}

class setLabel_Act implements ActionListener{

public void actionPerformed(ActionEvent e) {

}

}

public static void main(String[] args) {

}

}

2.建立构造方法：

所谓构造方法就是，对自己的主类进行初始化，代码如下：

private MyCaculator(){

jpt.setLayout(new BorderLayout());

jpt.add(jtf);

this.add(jpt,BorderLayout.NORTH);

jpb.setLayout(new GridLayout(4,4));

for(int i=0;ijba.length;i++){

jpb.add(jba[i]);

if(i==3||i==7||i==11||i==15||i==14)

jba[i].addActionListener(new setOperate_Act());

else

jba[i].addActionListener(new setLabel_Act());

}

this.add(jpb,BorderLayout.CENTER);

this.setSize(250, 200);

this.setResizable(false);

this.setVisible(true);

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

3.建立数据计算方法

这里的数据计算方法有6个，一个是主方法其他几个是加减乘除的处理方法，代码如下：

private void operate(String x){

double x1=Double.valueOf(x);

double y=Double.valueOf(output);

switch(op){

case 0:output=x;break;

case 1:output=String.valueOf(y+x1);break;

case 2:output =String.valueOf(y-x1);break;

case 3:output =String.valueOf(y*x1);break;

case 4:

if(x1!=0) output=String.valueOf(y/x1);

else output="不能为0";

break;

}

}

public String add(String x){

operate(x);

op=add;

return output;

}

public String subtract(String x){

operate(x);

op=sub;

return output;

}

public String multiply(String x){

operate(x);

op=mul;

return output;

}

public String divide(String x){

operate(x);

op=div;

return output;

}

public String Equals(String x){

operate(x);

op=0;

return output;

}

public void opClean(){

op=0;

output ="0";

}

4.事件处理方法

这里的时间处理方法，没有建立一个整体的方法，二是在为了便于处理的方法，将按钮事件分成两个部分，并采用两个子类来实现，这两个类时内部类要写在主类内部的，代码如下：

class setOperate_Act implements ActionListener{

public void actionPerformed(ActionEvent e) {

if(e.getSource()==jba[3]){

jtf.setText(add(jtf.getText()));

ifOp=true;

}

else if(e.getSource()==jba[7]){

jtf.setText(subtract(jtf.getText()));

ifOp=true;

}

else if(e.getSource()==jba[11]){

jtf.setText(multiply(jtf.getText()));

ifOp=true;

}

else if(e.getSource()==jba[15]){

jtf.setText(divide(jtf.getText()));

ifOp=true;

}

else if(e.getSource()==jba[14]){

jtf.setText(Equals(jtf.getText()));

ifOp=true;

}

}

}

class setLabel_Act implements ActionListener{

public void actionPerformed(ActionEvent e) {

Button tempb=(Button)e.getSource();

if(ifOp){

jtf.setText(tempb.getLabel());

ifOp=false;

}else {

jtf.setText(jtf.getText()+tempb.getLabel());

}

}

}

5.建立main方法：

要想实现我们的代码，我们需在main方法中，实例化我们的对象。

public static void main(String[] args) {

new MyCaculator();

}

用JAVA编写一个计算器

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.ImageIcon;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JTextField;

import javax.swing.SwingConstants;

public class Jisuanqi extends JFrame implements ActionListener {

/**

*

*/

private static final long serialVersionUID = 1L;

Result result = new Result(); // 定义text的面板

Number_Key number_key = new Number_Key(); // 定义按钮面板

// 当点击按钮+、-、*、/时，com = true

boolean com = false;

// 当i=0时说明是我们第一次输入，字符串text不会累加

int i = 0;

// 存放text的内容

String text = "";

// 存放点击按钮+、-、*、/之前的数值

double defbutton = 0;

// +、-、*、/的代号分别为1，2，3，4

int symbol = 0;

// 构造函数

Jisuanqi() {

super("计算器"); // 设定标题

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 设定关闭窗体时退出程序

JPanel pane = new JPanel(); // 定义主面板

pane.setLayout(new BorderLayout());

setBounds(380, 220, 30, 80); // 前两个参数是在屏幕上显示的坐标，后两个是大小

// 替换图标

ImageIcon icon = new ImageIcon("F:1.GIF");

// Jisuanqi.class.getResource("APPLE.GIF")

// );

setIconImage(icon.getImage());

pane.add(result, BorderLayout.NORTH);

pane.add(number_key, BorderLayout.CENTER);

pane.add(number_key.equal, BorderLayout.SOUTH);

number_key.one.addActionListener(this); // 对1按钮添加监听事件

number_key.two.addActionListener(this); // 对2按钮添加监听事件

number_key.three.addActionListener(this); // 对3按钮添加监听事件

number_key.four.addActionListener(this); // 对4按钮添加监听事件

number_key.five.addActionListener(this); // 对5按钮添加监听事件

number_key.six.addActionListener(this); // 对6按钮添加监听事件

number_key.seven.addActionListener(this); // 对7按钮添加监听事件

number_key.eight.addActionListener(this); // 对8按钮添加监听事件

number_key.nine.addActionListener(this); // 对9按钮添加监听事件

number_key.zero.addActionListener(this); // 对0按钮添加监听事件

number_key.ce.addActionListener(this); // 对置零按钮添加监听事件

number_key.plus.addActionListener(this); // 对+按钮添加监听事件

number_key.equal.addActionListener(this); // 对=按钮添加监听事件

number_key.sub.addActionListener(this); // 对-按钮添加监听事件

number_key.mul.addActionListener(this); // 对*按钮添加监听事件

number_key.div.addActionListener(this); // 对/按钮添加监听事件

number_key.point.addActionListener(this); // 对.按钮添加监听事件

setContentPane(pane);

pack(); // 初始化窗体大小为正好盛放所有按钮

}

// 各个按钮触发的事件

public void actionPerformed(ActionEvent e) {

/*

* 如果是点击数字按钮那么先要判断是否在此之前点击了+、-、*、/、=，如果是那么com=true 如果没有com=

* false;或者是否点击数字键，如果是i = 1,如果没有 i = 0;

*/

if (e.getSource() == number_key.one) {

if (com || i == 0) {

result.text.setText("1");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "1");

}

} else if (e.getSource() == number_key.two) {

if (com || i == 0) {

result.text.setText("2");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "2");

}

} else if (e.getSource() == number_key.three) {

if (com || i == 0) {

result.text.setText("3");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "3");

}

} else if (e.getSource() == number_key.four) {

if (com || i == 0) {

result.text.setText("4");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "4");

}

} else if (e.getSource() == number_key.five) {

if (com || i == 0) {

result.text.setText("5");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "5");

}

} else if (e.getSource() == number_key.six) {

if (com || i == 0) {

result.text.setText("6");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "6");

}

} else if (e.getSource() == number_key.seven) {

if (com || i == 0) {

result.text.setText("7");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "7");

}

} else if (e.getSource() == number_key.eight) {

if (com || i == 0) {

result.text.setText("8");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "8");

}

} else if (e.getSource() == number_key.nine) {

if (com || i == 0) {

result.text.setText("9");

com = false;

i = 1;

} else {

text = result.text.getText();

result.text.setText(text + "9");

}

}

/*

* 对于0这个按钮有一定的说法，在程序里不会出现如00000这样的情况，加了判断条件就是

* 如果text中的数值=0就要判断在这个数值中是否有.存在?如果有那么就在原来数值基础之上添 加0;否则保持原来的数值不变

*/

else if (e.getSource() == number_key.zero) { // result.text.getText()是得到text里内容的意思

if (com || i == 0) {

result.text.setText("0");

com = false;

i = 1;

} else {

text = result.text.getText();

if (Float.parseFloat(text) 0 || Float.parseFloat(text) 0) { // Float.parseFloat(text)就是类型转换了，下面都是一样

result.text.setText(text + "0");

} else {

if (text.trim().indexOf(".") == -1) {

result.text.setText(text);

} else {

result.text.setText(text + "0");

}

}

}

} else if (e.getSource() == number_key.ce) {

result.text.setText("0");

i = 0;

com = true;

// text = "";

defbutton = 0;

}

/*

* 本程序不会让一个数值中出现2个以上的小数点.具体做法是:判断是否已经存在.存在就不添加, 不存在就添加.

*/

else if (e.getSource() == number_key.point) {

if (com || i == 0) {

result.text.setText("0.");

com = false;

i = 1;

} else {

text = result.text.getText();

if (text.trim().indexOf(".") == -1) {

result.text.setText(text + ".");

} else {

result.text.setText(text);

}

}

} // 获得点击+之前的数值

else if (e.getSource() == number_key.plus) {

com = true;

i = 0;

defbutton = Double.parseDouble(result.text.getText());

symbol = 1;

} // 获得点击-之前的数值

else if (e.getSource() == number_key.sub) {

com = true;

i = 0;

defbutton = Double.parseDouble(result.text.getText());

symbol = 2;

} // 获得点击*之前的数值

else if (e.getSource() == number_key.mul) {

com = true;

i = 0;

defbutton = Double.parseDouble(result.text.getText());

System.out.println(defbutton);

symbol = 3;

} // 获得点击/之前的数值

else if (e.getSource() == number_key.div) {

com = true;

i = 0;

defbutton = Double.parseDouble(result.text.getText());

symbol = 4;

} else if (e.getSource() == number_key.equal) {

switch (symbol) {

case 1: { // 计算加法

double ad = defbutton

+ Double.parseDouble(result.text.getText());

result.text.setText(ad + "");

i = 0;

text = "";

break;

}

case 2: { // 计算减法

double ad = defbutton

- Double.parseDouble(result.text.getText());

result.text.setText(String.valueOf(ad));

i = 0;

text = "";

break;

}

case 3: { // 计算乘法

double ad = defbutton

* Double.parseDouble(result.text.getText());

result.text.setText(ad + "");

i = 0;

text = "";

break;

}

case 4: { // 计算除法

double ad = defbutton

/ Double.parseDouble(result.text.getText());

result.text.setText(ad + "");

i = 0;

text = "";

break;

}

}

System.out.println(com);

}

System.out.println(result.text.getText());

}

@SuppressWarnings("deprecation")

public static void main(String[] args) {

Jisuanqi loveyou = new Jisuanqi();

loveyou.show();

}

}

// 计算器数字按钮定义面板

class Number_Key extends JPanel {

/**

*

*/

private static final long serialVersionUID = 1L;

JButton zero = new JButton("0"); // 数字键0

JButton one = new JButton("1"); // 数字键1

JButton two = new JButton("2"); // 数字键2

JButton three = new JButton("3"); // 数字键3

JButton four = new JButton("4"); // 数字键4

JButton five = new JButton("5"); // 数字键5

JButton six = new JButton("6"); // 数字键6

JButton seven = new JButton("7"); // 数字键7

JButton eight = new JButton("8"); // 数字键8

JButton nine = new JButton("9"); // 数字键9

JButton plus = new JButton("+");

JButton sub = new JButton("-");

JButton mul = new JButton("*");

JButton div = new JButton("/");

JButton equal = new JButton("=");

JButton ce = new JButton("清零"); // 置零键

JButton point = new JButton(".");

Number_Key() {

setLayout(new GridLayout(4, 4, 1, 1)); // 定义布局管理器为网格布局

setBackground(Color.blue); // 设置背景颜色

// 添加按钮

add(one);

add(two);

add(three);

add(four);

add(five);

add(six);

add(seven);

add(eight);

add(nine);

add(zero);

add(plus);

add(sub);

add(mul);

add(div);

add(point);

add(equal);

add(ce);

}

}

// 计算器显示结果的窗体

class Result extends JPanel {

/**

*

*/

private static final long serialVersionUID = 1L;

// text先是输入和结果

JTextField text = new JTextField("0");

@SuppressWarnings("deprecation")

Result() { // 讲输入的数字或得到的结果在text的右边显示

text.setHorizontalAlignment(SwingConstants.RIGHT);

text.enable(false); // 文本框不能编辑

setLayout(new BorderLayout()); // 设定布局管理器边框布局

add(text, BorderLayout.CENTER); // text放置在窗体的中间

}

}

java 计算器代码

import javax.swing.*;

import javax.swing.border.Border;

import java.awt.*;

import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

import java.math.BigDecimal;

import java.math.RoundingMode;

import java.util.HashMap;

/**

* 我的计算器。Cheshi 继承于 JFrame，是计算器的界面

c*/

public class Cheshi extends JFrame {

private Border border = BorderFactory.createEmptyBorder(5, 5, 5, 5);

private JTextField textbox = new JTextField("0");

private CalculatorCore core = new CalculatorCore();

private ActionListener listener = new ActionListener() {

public void actionPerformed(ActionEvent e) {

JButton b = (JButton) e.getSource();

String label = b.getText();

String result = core.process(label);

textbox.setText(result);

}

};

public Cheshi(String title) throws HeadlessException {

super(title); // 调用父类构造方法

setupFrame(); // 调整窗体属性

setupControls(); // 创建控件

}

private void setupControls() {

setupDisplayPanel(); // 创建文本面板

setupButtonsPanel(); // 创建按钮面板

}

// 创建按钮面板并添加按钮

private void setupButtonsPanel() {

JPanel panel = new JPanel();

panel.setBorder(border);

panel.setLayout(new GridLayout(4, 5, 3, 3));

createButtons(panel, new String[]{

"7", "8", "9", "+", "C",

"4", "5", "6", "-", "CE",

"1", "2", "3", "*", "", // 空字符串表示这个位置没有按钮

"0", ".", "=", "/", ""

});

this.add(panel, BorderLayout.CENTER);

}

/**

* 在指定的面板上创建按钮

*

* @param panel 要创建按钮的面板

* @param labels 按钮文字

*/

private void createButtons(JPanel panel, String[] labels) {

for (String label : labels) {

// 如果 label 为空，则表示创建一个空面板。否则创建一个按钮。

if (label.equals("")) {

panel.add(new JPanel());

} else {

JButton b = new JButton(label);

b.addActionListener(listener); // 为按钮添加侦听器

panel.add(b);

}

}

}

// 设置显示面板，用一个文本框来作为计算器的显示部分。

private void setupDisplayPanel() {

JPanel panel = new JPanel();

panel.setLayout(new BorderLayout());

panel.setBorder(border);

setupTextbox();

panel.add(textbox, BorderLayout.CENTER);

this.add(panel, BorderLayout.NORTH);

}

// 调整文本框

private void setupTextbox() {

textbox.setHorizontalAlignment(JTextField.RIGHT); // 文本右对齐

textbox.setEditable(false); // 文本框只读

textbox.setBackground(Color.white); // 文本框背景色为白色

}

// 调整窗体

private void setupFrame() {

this.setDefaultCloseOperation(EXIT_ON_CLOSE); // 当窗体关闭时程序结束

this.setLocation(100, 50); // 设置窗体显示在桌面上的位置

this.setSize(300, 200); // 设置窗体大小

this.setResizable(false); // 窗体大小固定

}

// 程序入口

public static void main(String[] args) throws Exception {

UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

Cheshi frame = new Cheshi("我的计算器");

frame.setVisible(true); // 在桌面上显示窗体

}

}

/**

* 计算器核心逻辑。这个逻辑只能处理 1~2 个数的运算。

*/

class CalculatorCore {

private String displayText = "0"; // 要显示的文本

boolean reset = true;

private BigDecimal number1, number2;

private String operator;

private HashMapString, Operator operators = new HashMapString, Operator();

private HashMapString, Processor processors = new HashMapString, Processor();

CalculatorCore() {

setupOperators();

setupProcessors();

}

// 为每种命令添加处理方式

private void setupProcessors() {

processors.put("[0-9]", new Processor() {

public void calculate(String command) {

numberClicked(command);

}

});

processors.put("\\.", new Processor() {

public void calculate(String command) {

dotClicked();

}

});

processors.put("=", new Processor() {

public void calculate(String command) {

equalsClicked();

}

});

processors.put("[+\\-*/]", new Processor() {

public void calculate(String command) {

operatorClicked(command);

}

});

processors.put("C", new Processor() {

public void calculate(String command) {

clearClicked();

}

});

processors.put("CE", new Processor() {

public void calculate(String command) {

clearErrorClicked();

}

});

}

// 为每种 operator 添加处理方式

private void setupOperators() {

operators.put("+", new Operator() {

public BigDecimal process(BigDecimal number1, BigDecimal number2) {

return number1.add(number2);

}

});

operators.put("-", new Operator() {

public BigDecimal process(BigDecimal number1, BigDecimal number2) {

return number1.subtract(number2);

}

});

operators.put("*", new Operator() {

public BigDecimal process(BigDecimal number1, BigDecimal number2) {

return number1.multiply(number2);

}

});

operators.put("/", new Operator() {

public BigDecimal process(BigDecimal number1, BigDecimal number2) {

return number1.divide(number2, 30, RoundingMode.HALF_UP);

}

});

}

// 根据命令处理。这里的命令实际上就是按钮文本。

public String process(String command) {

for (String pattern : processors.keySet()) {

if (command.matches(pattern)) {

processors.get(pattern).calculate(command);

break;

}

}

return displayText;

}

// 当按下 CE 时

private void clearErrorClicked() {

if (operator == null) {

number1 = null;

} else {

number2 = null;

}

displayText = "0";

reset = true;

}

// 当按下 C 时，将计算器置为初始状态。

private void clearClicked() {

number1 = null;

number2 = null;

operator = null;

displayText = "0";

reset = true;

}

// 当按下 = 时

private void equalsClicked() {

calculateResult();

number1 = null;

number2 = null;

operator = null;

reset = true;

}

// 计算结果

private void calculateResult() {

number2 = new BigDecimal(displayText);

Operator oper = operators.get(operator);

if (oper != null) {

BigDecimal result = oper.process(number1, number2);

displayText = result.toString();

}

}

// 当按下 +-*/ 时（这里也可以扩展成其他中间操作符）

private void operatorClicked(String command) {

if (operator != null) {

calculateResult();

}

number1 = new BigDecimal(displayText);

operator = command;

reset = true;

}

// 当按下 . 时

private void dotClicked() {

if (displayText.indexOf(".") == -1) {

displayText += ".";

} else if (reset) {

displayText = "0.";

}

reset = false;

}

// 当按下 0-9 时

private void numberClicked(String command) {

if (reset) {

displayText = command;

} else {

displayText += command;

}

reset = false;

}

// 运算符处理接口

interface Operator {

BigDecimal process(BigDecimal number1, BigDecimal number2);

}

// 按钮处理接口

interface Processor {

void calculate(String command);

}

}

java编一个计算器的代码

界面漂亮堪比系统自带计算器，功能完美加减乘除开平方等等全部具备，还有清零按钮，小数点的使用，连加连乘功能完全参考系统官方计算器经过长期调试改进而成，马上拷贝代码拿去试试看吧，绝不后悔！

代码如下：

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.util.*;

public class Counter {

public static void main(String[] args) {

CounterFrame frame = new CounterFrame();

frame.show();

}

}

class CounterFrame extends JFrame {

public CounterFrame() {

JMenuBar menuBar = new JMenuBar();

JMenu menuFile = new JMenu();

JMenu menuFile1 = new JMenu();

JMenu menuFile2 = new JMenu();

JMenu menuFile3 = new JMenu();

JMenuItem menuFileExit = new JMenuItem();

menuFile.setText("文件");

menuFile1.setText("编辑");

menuFile2.setText("查看");

menuFile3.setText("帮助");

menuFileExit.setText("退出");

menuFileExit.addActionListener

(

new ActionListener() {

public void actionPerformed(ActionEvent e) {

CounterFrame.this.windowClosed();

}

}

);

menuFile.add(menuFileExit);

menuBar.add(menuFile);

menuBar.add(menuFile1);

menuBar.add(menuFile2);

menuBar.add(menuFile3);

setTitle("计算器");

setJMenuBar(menuBar);

setSize(new Dimension(400, 280));

this.getContentPane().add(new Allpanel());

this.addWindowListener

(

new WindowAdapter() {

public void windowClosing(WindowEvent e) {

CounterFrame.this.windowClosed();

}

}

);

}

protected void windowClosed() {

System.exit(0);

}

}

class Tool {

public static Tool instance;

private JTextField field;

private Tool() {

this.field=new JTextField(30);

this.field.setHorizontalAlignment(JTextField.RIGHT);

}

public static Tool getinstance()

{

if(instance==null)

{

instance=new Tool();

}

return instance;

}

public JTextField getfield()

{

return (this.field);

}

}

class Allpanel extends JPanel {

public Allpanel() {

this.setLayout(new BorderLayout(0,7));

Northpanel np=new Northpanel();

Centerpanel cp=new Centerpanel();

this.add(np,BorderLayout.NORTH);

this.add(cp,BorderLayout.CENTER);

}

}

class Centercenter extends JPanel {

static Vector Vec=new Vector();

static Vector vc=new Vector();

static Vector vc1=new Vector();

static Vector vc2=new Vector();

static Vector vc3=new Vector();

static String begin="yes";

static double add;

static double jq;

static double cs;

static double cq;

static double dy;

static String jg;

static String what;

static double tool=0;

static String to="yes";

/**

* Method Centercenter

*

*

*/

public Centercenter() {

// TODO: Add your code here

final JTextField text=Tool.getinstance().getfield();

this.setLayout(new GridLayout(4,5,3,3));

String arg[] ={"7","8","9","/","sqrt","4","5","6","*","%","1","2","3","-","1/x","0","+/-",".","+","="};

for(int i=0;i20;i++)

{

final JButton b=new JButton(arg[i]);

//this.add(new JButton(arg[i]));

this.add(b);

if(i==0||i==1||i==2||i==5||i==6||i==7||i==10||i==11||i==12||i==15)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String mark=b.getText();

String ma=text.getText();

if(vc3.contains("v3"))

{

text.setText("0."+mark);

vc3.clear();

}

else if(vc.contains("a"))

{

if(vc2.contains("v2"))

{

text.setText("0."+mark);

vc.clear();

vc2.clear();

}

else

{

text.setText(mark);

vc.clear();

Vec.clear();

Vec.add(mark);

}

}

else

{

text.setText(ma.trim()+mark);

Vec.add(mark);

}

begin="no";

to="yes";

}

});

}

if(i==17)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String mar=b.getText();

String m=text.getText();

if("yes".equals(begin))

{

vc3.add("v3");

}

if(vc1.contains("v1"))

{

vc2.add("v2");

vc1.clear();

}

if(!Vec.contains(".")!vc.contains("a"))

{

text.setText(m.trim()+mar);

Vec.add(".");

}

}

});

}

if(i==18)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

add=Double.parseDouble(ma);

if(what==null)

{

tool=add;

what="add";

}

else

{

tool=tool+add;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="+";

}

});

}

if(i==13)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

jq=Double.parseDouble(ma);

if(what==null)

{

tool=jq;

what="jq";

}

else

{

tool=tool-jq;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="-";

}

});

}

if(i==3)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

cq=Double.parseDouble(ma);

if(what==null)

{

tool=cq;

what="cq";

}

else

{

tool=tool/cq;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="/";

}

});

}

if(i==4)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

cq=Double.parseDouble(ma);

text.setText(String.valueOf(Math.sqrt(cq)));

}

});

}

if(i==8)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

cs=Double.parseDouble(ma);

if(what==null)

{

tool=cs;

what="cs";

}

else

{

tool=tool*cs;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="*";

}

});

}

if(i==19)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

dy=Double.parseDouble(ma);

if(what=="add")

{

jg=String.valueOf((tool+dy));

}

if(what=="jq")

{

jg=String.valueOf((tool-dy));

}

if(what=="cs")

{

jg=String.valueOf((tool*dy));

}

if(what=="cq")

{

jg=String.valueOf((tool/dy));

}

if(what==null)

{

if(to=="+")

{

tool=add;

jg=String.valueOf(tool+dy);

}

else if(to=="-")

{

tool=jq;

jg=String.valueOf(dy-tool);

}

else if(to=="*")

{

tool=cs;

jg=String.valueOf(dy*tool);

}

else if(to=="/")

{

tool=cq;

jg=String.valueOf(dy/tool);

}

else

{

jg=String.valueOf(dy);

}

}

text.setText(jg);

Vec.clear();

Vec.add(".");

vc.add("a");

vc1.add("v1");

what=null;

tool=0;

}

});

}

}

}

}

class Centernorth extends JPanel {

public Centernorth() {

final JTextField text=Tool.getinstance().getfield();

JButton jb1=new JButton("Backspace");

JButton jb2=new JButton(" CE ");

JButton jb3=new JButton(" C ");

this.add(jb1);

this.add(jb2);

this.add(jb3);

jb1.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e)

{

String back=Tool.getinstance().getfield().getText();

text.setText(backmethod(back));

Centercenter.Vec.remove(Centercenter.Vec.size()-1);

}

});

jb3.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e)

{

text.setText("0.");

Centercenter.Vec.clear();

Centercenter.Vec.add(".");

Centercenter.vc.add("a");

Centercenter.begin="yes";

Centercenter.vc1.clear();

Centercenter.what=null;

Centercenter.tool=0;

}

});

}

public String backmethod(String str)

{

return str.substring(0,str.length()-1);

}

}

class Centerpanel extends JPanel {

public Centerpanel() {

this.setLayout(new BorderLayout(8,7));

Centernorth cn=new Centernorth();

Centercenter cc=new Centercenter();

Centerwest cw=new Centerwest();

this.add(cn,BorderLayout.NORTH);

this.add(cc,BorderLayout.CENTER);

this.add(cw,BorderLayout.WEST);

}

}

class Centerwest extends JPanel {

public Centerwest() {

this.setLayout(new GridLayout(4,1,3,3));

this.add(new JButton("MC"));

this.add(new JButton("MR"));

this.add(new JButton("MS"));

this.add(new JButton("M+"));

}

}

class Northpanel extends JPanel {

private JTextField tf;

public Northpanel() {

tf=Tool.getinstance().getfield();

this.add(tf);

}

}

---------------------------------------------------------------------------

=============《按你要求特意后改过的最简单功能的代码如下》========================

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.util.*;

public class Counter2 {

public static void main(String[] args) {

CounterFrame frame = new CounterFrame();

frame.show();

}

}

class CounterFrame extends JFrame {

public CounterFrame() {

setTitle("计算器");

setSize(new Dimension(400, 280));

this.getContentPane().add(new Allpanel());

this.addWindowListener

(

new WindowAdapter() {

public void windowClosing(WindowEvent e) {

CounterFrame.this.windowClosed();

}

}

);

}

protected void windowClosed() {

System.exit(0);

}

}

class Tool {

public static Tool instance;

private JTextField field;

private Tool() {

this.field=new JTextField(30);

this.field.setHorizontalAlignment(JTextField.RIGHT);

}

public static Tool getinstance()

{

if(instance==null)

{

instance=new Tool();

}

return instance;

}

public JTextField getfield()

{

return (this.field);

}

}

class Allpanel extends JPanel {

public Allpanel() {

this.setLayout(new BorderLayout(0,7));

Northpanel np=new Northpanel();

Centerpanel cp=new Centerpanel();

this.add(np,BorderLayout.NORTH);

this.add(cp,BorderLayout.CENTER);

}

}

class Centercenter extends JPanel {

static Vector Vec=new Vector();

static Vector vc=new Vector();

static Vector vc1=new Vector();

static Vector vc2=new Vector();

static Vector vc3=new Vector();

static String begin="yes";

static double add;

static double jq;

static double cs;

static double cq;

static double dy;

static String jg;

static String what;

static double tool=0;

static String to="yes";

/**

* Method Centercenter

*

*

*/

public Centercenter() {

// TODO: Add your code here

final JTextField text=Tool.getinstance().getfield();

this.setLayout(new GridLayout(4,5,3,3));

String arg[] ={"7","8","9","/","4","5","6","*","1","2","3","-","0","=",".","+"};

for(int i=0;i16;i++)

{

final JButton b=new JButton(arg[i]);

//this.add(new JButton(arg[i]));

this.add(b);

if(i==0||i==1||i==2||i==4||i==5||i==6||i==8||i==9||i==10||i==12)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String mark=b.getText();

String ma=text.getText();

if(vc3.contains("v3"))

{

text.setText("0."+mark);

vc3.clear();

}

else if(vc.contains("a"))

{

if(vc2.contains("v2"))

{

text.setText("0."+mark);

vc.clear();

vc2.clear();

}

else

{

text.setText(mark);

vc.clear();

Vec.clear();

Vec.add(mark);

}

}

else

{

text.setText(ma.trim()+mark);

Vec.add(mark);

}

begin="no";

to="yes";

}

});

}

if(i==14)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String mar=b.getText();

String m=text.getText();

if("yes".equals(begin))

{

vc3.add("v3");

}

if(vc1.contains("v1"))

{

vc2.add("v2");

vc1.clear();

}

if(!Vec.contains(".")!vc.contains("a"))

{

text.setText(m.trim()+mar);

Vec.add(".");

}

}

});

}

if(i==15)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

add=Double.parseDouble(ma);

if(what==null)

{

tool=add;

what="add";

}

else

{

tool=tool+add;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="+";

}

});

}

if(i==11)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

jq=Double.parseDouble(ma);

if(what==null)

{

tool=jq;

what="jq";

}

else

{

tool=tool-jq;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="-";

}

});

}

if(i==3)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

cq=Double.parseDouble(ma);

if(what==null)

{

tool=cq;

what="cq";

}

else

{

tool=tool/cq;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="/";

}

});

}

if(i==7)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

cs=Double.parseDouble(ma);

if(what==null)

{

tool=cs;

what="cs";

}

else

{

tool=tool*cs;

text.setText(String.valueOf((tool)));

}

vc.add("a");

vc1.add("v1");

to="*";

}

});

}

if(i==13)

{

b.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

String ma=text.getText();

dy=Double.parseDouble(ma);

if(what=="add")

{

jg=String.valueOf((tool+dy));

}

if(what=="jq")

{

jg=String.valueOf((tool-dy));

}

if(what=="cs")

{

jg=String.valueOf((tool*dy));

}

if(what=="cq")

{

jg=String.valueOf((tool/dy));

}

if(what==null)

{

if(to=="+")

{

tool=add;

jg=String.valueOf(tool+dy);

}

else if(to=="-")

{

tool=jq;

jg=String.valueOf(dy-tool);

}

else if(to=="*")

{

tool=cs;

jg=String.valueOf(dy*tool);

}

else if(to=="/")

{

tool=cq;

jg=String.valueOf(dy/tool);

}

else

{

jg=String.valueOf(dy);

}

}

text.setText(jg);

Vec.clear();

Vec.add(".");

vc.add("a");

vc1.add("v1");

what=null;

tool=0;

}

});

}

}

}

}

class Centernorth extends JPanel {

public Centernorth() {

final JTextField text=Tool.getinstance().getfield();

}

}

class Centerpanel extends JPanel {

public Centerpanel() {

this.setLayout(new BorderLayout(8,7));

Centernorth cn=new Centernorth();

Centercenter cc=new Centercenter();

Centerwest cw=new Centerwest();

this.add(cn,BorderLayout.NORTH);

this.add(cc,BorderLayout.CENTER);

this.add(cw,BorderLayout.WEST);

}

}

class Centerwest extends JPanel {

public Centerwest() {

}

}

class Northpanel extends JPanel {

private JTextField tf;

public Northpanel() {

tf=Tool.getinstance().getfield();

this.add(tf);

}

}

------------------------------------------------------------

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