java实现简单计算器功能

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
//import javax.swing.JOptionPane;

public class MyCalculator_18 implements ActionListener { // 导入动作监听接口
// 设计面板中的单位
JFrame frame;

JTextField textAnswer;

JPanel panel1, panel2, panel3;

JLabel labelMemSpace; // labelMemSpace单纯做摆设，控制面板的形状

JButton buttonBk, buttonCe, buttonC;

JButton button[];

JButton buttonDot, buttonAddAndSub, buttonAdd, buttonSub, buttonMul,
buttonDiv, buttonMod;

JButton buttonSqrt, buttonDao, buttonEqual;

DecimalFormat df; // 设置数据输出精度

boolean clickable; // 控制当前能否按键


double vard, answerd; // 用来保存double型数据的中间值(vard)和最后结果(answerd)

short key = -1, prekey = -1; // key用来保存当前进行何种运算,prekey用来保存前次进行何种运算

String copy; // 做复制用

JTextArea help; // 帮助


// 构造函数
public MyCalculator_18() {
clickable = true;
answerd = 0;
frame = new JFrame("计算器");
df = new DecimalFormat("0.##############"); // 设置数据输出精度(对于double型值)
textAnswer = new JTextField(15);
textAnswer.setText("");
textAnswer.setEditable(false);
textAnswer.setBackground(new Color(255, 255, 255));

panel1 = new JPanel();
panel2 = new JPanel();
frame.getContentPane().add(panel1);
panel1.setLayout(new BorderLayout());
// 设计整个面板

panel1.add(textAnswer, BorderLayout.NORTH);
labelMemSpace = new JLabel(" ");
buttonBk = new JButton("Backspace");
buttonBk.setForeground(new Color(255, 0, 0));
buttonCe = new JButton("CE");
buttonCe.setForeground(new Color(255, 0, 0));
buttonC = new JButton("C");
buttonC.setForeground(new Color(255, 0, 0));
buttonBk.addActionListener(this);
buttonCe.addActionListener(this);
buttonC.addActionListener(this);
panel1.add(panel2, BorderLayout.CENTER);
panel2.setLayout(new FlowLayout(FlowLayout.RIGHT));
panel2.add(labelMemSpace);
panel2.add(buttonBk);
panel2.add(buttonCe);
panel2.add(buttonC);
panel3 = new JPanel();
panel1.add(panel3, BorderLayout.SOUTH);
button = new JButton[10];
for (int i = 0; i < button.length; i++) {
button[i] = new JButton(Integer.toString(i));
button[i].setForeground(new Color(0, 0, 255));
}
buttonDot = new JButton(".");
buttonDot.setForeground(new Color(0, 0, 255));
buttonAddAndSub = new JButton("+/-");
buttonAddAndSub.setForeground(new Color(0, 0, 255));
buttonAdd = new JButton("+");
buttonAdd.setForeground(new Color(255, 0, 0));
b

uttonSub = new JButton("-");
buttonSub.setForeground(new Color(255, 0, 0));
buttonMul = new JButton("*");
buttonMul.setForeground(new Color(255, 0, 0));
buttonDiv = new JButton("/");
buttonDiv.setForeground(new Color(255, 0, 0));
buttonMod = new JButton("%");
buttonMod.setForeground(new Color(0, 0, 255));
buttonSqrt = new JButton("sqrt");
buttonSqrt.setForeground(new Color(0, 0, 255));
buttonDao = new JButton("1/x");
buttonDao.setForeground(new Color(0, 0, 255));
buttonEqual = new JButton("=");
buttonEqual.setForeground(new Color(255, 0, 0));
// 将所有行为与监听绑定
panel3.setLayout(new GridLayout(4, 5));
panel3.add(button[7]);
button[7].addActionListener(this);
panel3.add(button[8]);
button[8].addActionListener(this);
panel3.add(button[9]);
button[9].addActionListener(this);
panel3.add(buttonDiv);
buttonDiv.addActionListener(this);
panel3.add(buttonSqrt);
buttonSqrt.addActionListener(this);
panel3.add(button[4]);
button[4].addActionListener(this);
panel3.add(button[5]);
button[5].addActionListener(this);
panel3.add(button[6]);
button[6].addActionListener(this);
panel3.add(buttonMul);
buttonMul.addActionListener(this);
panel3.add(buttonMod);
buttonMod.addActionListener(this);
panel3.add(button[1]);
button[1].addActionListener(this);
panel3.add(button[2]);
button[2].addActionListener(this);
panel3.add(button[3]);
button[3].addActionListener(this);
panel3.add(buttonSub);
buttonSub.addActionListener(this);
panel3.add(buttonDao);
buttonDao.addActionListener(this);
panel3.add(button[0]);
button[0].addActionListener(this);
panel3.add(buttonAddAndSub);
buttonAddAndSub.addActionListener(this);
panel3.add(buttonDot);
buttonDot.addActionListener(this);
panel3.add(buttonAdd);
buttonAdd.addActionListener(this);
panel3.add(buttonEqual);
buttonEqual.addActionListener(this);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}

// 设置各个按钮行为
public void actionPerformed(ActionEvent event) {
Object temp = event.getSource();
// 如果按下数据按钮，将按下的按钮代表的数据插入的当前文本框字符串之后
for (int i = 0; i <= 9; i++)
if (temp == button[i] && clickable == true)
textAnswer.setText(textAnswer.getText()
+ Integer.toString(i));


// 按下"."按钮时，判断当前文本框内字符串中含不含"."，如果已含，则不允许再插入"."
if (temp == buttonDot && clickable == true) {
boolean isDot = false;
if (textAnswer.getText().length() == 0)
isDot = true;
for (int i = 0; i < textAnswer.getText().length(); i++)
if ('.' == textAnswer.getText().charAt(i)) {
isDot = true;
break;
}
if (isDot == false)
textAnswer.setText(textAnswer.getText() + ".");
}
if((temp==buttonAdd||temp==buttonSub||temp==butt

onMul||temp==buttonDiv)&&clickable == true)
{
//+
if(temp==buttonAdd){
switch(prekey){
case 0:
answerd +=Double.parseDouble(textAnswer.getText());
case 1:
answerd -=Double.parseDouble(textAnswer.getText());
case 2:
answerd *=Double.parseDouble(textAnswer.getText());
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {

textAnswer.setText("除数不能为零");
clickable = false;
} else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 0;
}
//-
if(temp==buttonSub){
switch(prekey){
case 0:
answerd +=Double.parseDouble(textAnswer.getText());
case 1:
answerd -=Double.parseDouble(textAnswer.getText());
case 2:
answerd *=Double.parseDouble(textAnswer.getText());
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {

textAnswer.setText("除数不能为零");
clickable = false;
} else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 1;
}
//*
if(temp==buttonMul){
switch(prekey){
case 0:
answerd +=Double.parseDouble(textAnswer.getText());
case 1:
answerd -=Double.parseDouble(textAnswer.getText());
case 2:
answerd *=Double.parseDouble(textAnswer.getText());
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {

textAnswer.setText("除数不能为零");
clickable = false;
} else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 2;
}
///
if(temp==buttonDiv){
switch(prekey){
case 0:
answerd +=Double.parseDouble(textAnswer.getText());
case 1:
answerd -=Double.parseDouble(textAnswer.getText());
case 2:
answerd *=Double.parseDouble(textAnswer.getText());
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {

textAnswer.setText("除数不能为零");
clickable = false;
} else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 3;
}

}
//=
if(temp==buttonEqual && clickable == true){
if (prekey == 5) {
if (key == 0) {
answerd += vard;
textAnswer.setText(df.format(answerd));
}
if (key == 1) {
answerd -= vard;
textAnswer.setText(df.format(answerd));
}
if (key == 2) {
answerd *= vard;
textAnswer.setText(df.format(answerd));
}
if (

key == 3) {
answerd /= vard;
textAnswer.setText(df.format(answerd));
}


} else {
vard = Double.parseDouble(textAnswer.getText());
if (key == 0) {
prekey = -1;
answerd += Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}
if (key == 1) {
prekey = -1;
answerd -= Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}
if (key == 2) {
prekey = -1;
answerd *= Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}
if (key == 3) {
prekey = -1;
answerd /= Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}


}
prekey = 5;
}
//取余
if(temp ==buttonMod && clickable == true){
if(answerd == 0){
String s= textAnswer.getText();
textAnswer.setText(s);
}else{

}
}
//开根号
if(temp == buttonSqrt&& clickable == true){
String s=textAnswer.getText();
if(s.charAt(0)=='-'){
textAnswer.setText("不能开根");
clickable = false;
}else{
textAnswer.setText(Double.toString(https://www.doczj.com/doc/732531492.html,ng.Math.sqrt(Double.parseDouble(textAnswer.getText()))));
}
}
//求倒数
if(temp == buttonDao&& clickable == true){
String s=textAnswer.getText();
if(s.charAt(0)=='0'&&s.length()==1){
textAnswer.setText("0没有倒数");
clickable = false;
}else{
boolean isDec=true;

}
}

//正负号
if(temp==buttonAddAndSub&& clickable == true ){
String tem=textAnswer.getText();
if(tem.charAt(0)=='-'){
textAnswer.setText("");
for(int j=1;jtextAnswer.setText(textAnswer.getText()+tem.charAt(j));}
}else{
tem="-"+tem;
textAnswer.setText(tem);}
}
//Ce
if(temp==buttonCe){
textAnswer.setText("");

}
//C
if(temp==buttonC){
vard=answerd=0;
textAnswer.setText("");
}
//退格
if(temp==buttonBk){
String str1;
str1=textAnswer.getText();
textAnswer.setText("");
for(int j=0;jchar c=str1.charAt(j);
textAnswer.setText(textAnswer.getText()+c);}

}}

// 主函数
public static void main(String args[]) {
new MyCalculator_18();
}
}