import javax.swing.*;
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import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener
{
private boolean dotExist, operated, equaled; // 帮助运算的布尔变量
private double storedNumber; // 目前的结果
private char lastOperator; // 表示上一运算符
private JTextField operation; // 结果栏
private JButton dot, plus, minus, multi, div, sqrt, equal, changePN, clear; // 运算符
private JButton[] numbers; // 数字
// 构造者
public Calculator()
{
setTitle("Calculator");
// 初始化变量
dotExist = false; // 表示当前的数是否有小数点
operated = false; // 表示任意运算符是否被按下
equaled = false; // 表示等号是否被按下
storedNumber = 0;
lastOperator = '?';
// 初始化窗口变量
operation = new JTextField("0");
operation.setEditable(false);
numbers = new JButton[10];
for (int i = 0; i 10; i++)
numbers[i] = new JButton("" + i);
dot = new JButton(".");
plus = new JButton("+");
minus = new JButton("-");
multi = new JButton("*");
div = new JButton("/");
sqrt = new JButton("√");
equal = new JButton("=");
changePN = new JButton("±");
clear = new JButton("AC");
// 将窗口物体放入窗口
GridBagLayout layout = new GridBagLayout();
getContentPane().setLayout(layout);
addComponent(layout, operation, 0, 0, 4, 1);
addComponent(layout, numbers[1], 1, 0, 1, 1);
addComponent(layout, numbers[2], 1, 1, 1, 1);
addComponent(layout, numbers[3], 1, 2, 1, 1);
addComponent(layout, numbers[4], 2, 0, 1, 1);
addComponent(layout, numbers[5], 2, 1, 1, 1);
addComponent(layout, numbers[6], 2, 2, 1, 1);
addComponent(layout, numbers[7], 3, 0, 1, 1);
addComponent(layout, numbers[8], 3, 1, 1, 1);
addComponent(layout, numbers[9], 3, 2, 1, 1);
addComponent(layout, dot, 4, 0, 1, 1);
addComponent(layout, numbers[0], 4, 1, 1, 1);
addComponent(layout, sqrt, 4, 2, 1, 1);
addComponent(layout, plus, 1, 3, 1, 1);
addComponent(layout, minus, 2, 3, 1, 1);
addComponent(layout, multi, 3, 3, 1, 1);
addComponent(layout, div, 4, 3, 1, 1);
addComponent(layout, equal, 5, 0, 2, 1);
addComponent(layout, changePN, 5, 2, 1, 1);
addComponent(layout, clear, 5, 3, 1, 1);
}
// 对按钮进行反应的方法
public void actionPerformed(ActionEvent e)
{
JButton btn = (JButton)e.getSource();
if (btn == clear)
{
operation.setText("0");
dotExist = false;
storedNumber = 0;
lastOperator = '?';
}
else if (btn == equal)
{
operate('=');
equaled = true;
}
else if (btn == plus)
{
operate('+');
equaled = false;
}
else if (btn == minus)
{
operate('-');
equaled = false;
}
else if (btn == multi)
{
operate('*');
equaled = false;
}
else if (btn == div)
{
operate('/');
equaled = false;
}
else if (btn == changePN)
{
operate('p');
operate('=');
equaled = true;
}
else if (btn == sqrt)
{
operate('s');
operate('=');
equaled = true;
}
else
{
if (equaled)
storedNumber = 0;
for (int i = 0; i 10; i++)
if (btn == numbers[i])
{
if (operation.getText().equals("0"))
operation.setText("" + i);
else if(! operated)
operation.setText(operation.getText() + i);
else
{
operation.setText("" + i);
operated = false;
}
}
if (btn == dot ! dotExist)
{
operation.setText(operation.getText() + ".");
dotExist = true;
}
}
}
// 进行运算的方法
private void operate(char operator)
{
double currentNumber = Double.valueOf(operation.getText()).doubleValue();
if (lastOperator == '?')
storedNumber = currentNumber;
else if (lastOperator == '+')
storedNumber += currentNumber;
else if (lastOperator == '-')
storedNumber -= currentNumber;
else if (lastOperator == '*')
storedNumber *= currentNumber;
else if (lastOperator == '/')
storedNumber /= currentNumber;
else if (lastOperator == 'p')
storedNumber *= -1;
else if (lastOperator == 's')
storedNumber = Math.sqrt(currentNumber);
else if (lastOperator == '=' equaled)
storedNumber = currentNumber;
operation.setText("" + storedNumber);
operated = true;
lastOperator = operator;
}
// 快捷使用GridBagLayout的方法
private void addComponent(GridBagLayout layout, Component component, int row, int col, int width, int height)
{
GridBagConstraints constraints = new GridBagConstraints();
constraints.fill = GridBagConstraints.BOTH;
constraints.insets = new Insets(10, 2, 10, 2);
constraints.weightx = 100;
constraints.weighty = 100;
constraints.gridx = col;
constraints.gridy = row;
constraints.gridwidth = width;
constraints.gridheight = height;
layout.setConstraints(component, constraints);
if (component instanceof JButton)
((JButton)component).addActionListener(this);
getContentPane().add(component);
}
// 主方法初始化并显示窗口
public static void main(String[] args)
{
Calculator calc = new Calculator();
calc.setSize(290, 400);
calc.setVisible(true);
}
}
public class Excer{
public static void main(String args[])
{
Excer ex=new Excer();
int x=0;
int y=0;
ex.math(x,y);
}
void math(int x,int y){
MyMath mm = new MyMath();
System.out.println("x="+x+" ,y="+y);
System.out.println("x+y="+mm.plus(x,y));
System.out.println("x-y="+mm.minus(x,y));
System.out.println("x*y="+mm.multi(x,y));
System.out.println("x/y="+mm.div(x,y));
}
}
class MyMath
{
int plus(int a,int b)
{
return(a+b);
}
int minus(int a,int b)
{
return(a-b);
}
int multi(int a,int b)
{
return(a*b);
}
float div(int a,int b)
{
return ((float)a/b);
}
}
public class MyComputer implements ActionListener{
private boolean appendnumber = false;
private boolean append = false;
private boolean flag = false;
private String temp1 = null;
private String op1 = null;
private JTextField jtf = new JTextField("0.",28);
public MyComputer(){
init();
}
private void init() {
/*
* 下面都是在画计算机界面你想看也可以，
* 不看也行，具体计算在public void
* actionPerformed(ActionEvent e)
* 里
*/
JFrame frame = new JFrame("我的计算器");
JPanel panelTop = new JPanel();
panelTop.setLayout(new FlowLayout());
panelTop.add(jtf);
JPanel panelBotton = new JPanel();
String[] str = {"BackSpace","CE","C","+",
"7","8","9","-",
"4","5","6","*",
"1","2","3","/",
"0","+/-",".","="};
JButton[] jb = new JButton[str.length];
panelBotton.setLayout(new GridLayout(5,4));
for(int i = 0;i jb.length;i++)
{
jb[i] = new JButton(str[i]);
panelBotton.add(jb[i]);
jb[i].addActionListener(this);
}
frame.add(panelTop,BorderLayout.NORTH);
frame.add(panelBotton);
frame.setSize(400, 400);
frame.setVisible(true);
}
public static void main(String[] args) {
new MyComputer();
}
public void actionPerformed(ActionEvent e) {
String comm = e.getActionCommand();//获得button里的数据
/*
* "0123456789".indexOf(comm)!=-1是判断button里获得的数据
* 是0---9的情况
*/
if ("0123456789".indexOf(comm)!=-1) {
if(!appendnumber){
jtf.setText(comm);
appendnumber = true;
}else{
jtf.setText(jtf.getText()+comm);
}
}
/*
* 判断button里获得的数据是加减乘除的情况
*/
if("+-*/".indexOf(comm)!=-1){
//在遇到加减乘除的符号时我们先存储刚输入的值
temp1 = jtf.getText();
//然后存储符号
op1 = comm;
/*
* 然后可以重新输入数据到输入框，所以这时候我们
* 不能追加数据，设置追加数据标志为false
*/
appendnumber = false;
}
/*
* 判断button里获得的数据是等号的情况
*/
else if("=".equals(comm)) {
if(temp1==null||"".equals(temp1))return;
/*
* 遇到等号的时候，我们取出刚才保存的数据和当前输入的数据做运算
*/
double num1 = Double.parseDouble(temp1);//转化数据成double型的
double num2 = Double.parseDouble(jtf.getText());//转化数据成double型的
//取出刚才保存的符号看是加减乘除的那种运算
if("+".equals(op1)){
num1+=num2;
}
if("-".equals(op1)){
num1-=num2;
}
if ("*".equals(op1)) {
num1*=num2;
}
if("/".equals(op1)){
num1/=num2;
}
jtf.setText(num1+"");
appendnumber = false;
}
/*
* 判断button里获得的数据是小数点的情况
*/
else if (".".equals(comm)) {
if(jtf.getText().indexOf(".")==-1){
append = true;
}
if (append) {
jtf.setText(jtf.getText()+".");
append = false;
appendnumber = true;
}
}
/*
* 判断button里获得的数据是在数据前面加正负号的情况
*/
else if ("+/-".equals(comm)) {
if(!flag){
jtf.setText("-"+jtf.getText());
flag = true;
}
else{
String result = jtf.getText().substring(1, jtf.getText().length());
jtf.setText(result);
flag = false;
}
}
/*
* 判断button里获得的数据是清除输入框的情况
*/
else if ("C".equals(comm)) {
jtf.setText("0.");
appendnumber = false;
}
/*
* 判断button里获得的数据是清除输入框的情况
*/
else if ("CE".equals(comm)) {
jtf.setText("0.");
appendnumber = false;
}
/*
* 判断button里获得的数据是输入框的数据退一位的情况
*/
else if ("BackSpace".equals(comm)) {
if(jtf.getText()==null||"".equals(jtf.getText()))return;
String result = jtf.getText().substring(0, jtf.getText().length()-1);
jtf.setText(result+"");
appendnumber = true;
}
}
}
很简单的东西啊！你们去分那么多情况啊！这个东西啊一个人写半个小时就OK了，如果你会写的话，其实初学者们别因为别人怎么怎么说就吓倒，其实这写起来都没多少代码的，都是些小东西而已。最重要的是你要搞懂来龙去脉就不难了，别听一些人吹谁谁牛X这类的，其实你认真的去做，认真的去思考，你也不比他们差。
java编程实现分数的加减乘除运算的步骤如下：
1、打开eclipse，创建一个Java工程，在此工程里新建一个类；
2、在新建的类中，添加4个运算类；
3、在主方法中调用对应的方法即可完成分数的加减乘除运算了。
具体实现代码如下：
public class Demo {
public static void main(String[] args) {
System.out.println(jia(1, 2));
System.out.println(jian(1, 2));
System.out.println(cheng(1, 2));
System.out.println(chu(1, 2));
}
//加法运算
private static float jia(float x,float y) {
return x + y;
}
//减法运算
private static float jian(float x,float y) {
return x - y;
}
//乘法运算
private static float cheng(float x,float y) {
return x * y;
}
//除法运算
private static float chu(float x,float y) {
return x / y;
}
}
用Java编写的实现加减乘除的程序如下
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Calculator extends JFrame implements ActionListener{
JLabel jl1=new JLabel("第一个数");
JLabel jl2=new JLabel("运算符");
JLabel jl3=new JLabel("第二个数");
JLabel jl4=new JLabel("结果:");
JTextField jtf1=new JTextField(8);
JTextField jtf2=new JTextField(8);
JTextField jtf3=new JTextField(8);
String a[]={"+","-","*","/"};
JComboBoxString jcb=new JComboBoxString(a);
JButton jb1=new JButton("计算");
JButton jb2=new JButton("退出");
JPanel jp=new JPanel();
Calculator(){
setTitle("计算器");
jb1.addActionListener(this);
jb2.addActionListener(this);
jp.setLayout(null);
jl1.setBounds(30, 30, 80, 20);
jl2.setBounds(110, 30, 80, 20);
jl3.setBounds(190, 30, 80, 20);
jtf1.setBounds(30, 60, 70, 20);
jcb.setBounds(110, 60, 70,20);
jtf2.setBounds(190, 60, 70, 20);
jl4.setBounds(80, 110, 40, 20);
jtf3.setBounds(110, 110, 100, 20);
jb1.setBounds(60, 160, 60, 25);
jb2.setBounds(170, 160, 60, 25);
jp.add(jl1);jp.add(jl2);jp.add(jl3);
jp.add(jtf1);jp.add(jcb);jp.add(jtf2);
jp.add(jl4);jp.add(jtf3);
jp.add(jb1);jp.add(jb2);
add(jp,BorderLayout.CENTER);
setSize(300, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
public static void main(String[] args) {
new Calculator();
}
@Override
public void actionPerformed(ActionEvent ae) {
if(ae.getSource()==jb1){
String c=((String) jcb.getSelectedItem()).trim();
if(jtf1.getText().trim().equals("")){
JOptionPane.showMessageDialog(this, "第一个数不能为空");
jtf1.requestFocus();
return;
}
if(jtf2.getText().trim().equals("")){
JOptionPane.showMessageDialog(this, "第二个数不能为空");
jtf2.requestFocus();
return;
}
double num1=Double.parseDouble(jtf1.getText().trim());
double num2=Double.parseDouble(jtf2.getText().trim());
double num3 = 0;
switch(c){
case "+":num3=num1+num2;break;
case "-":num3=num1-num2;break;
case "*":num3=num1*num2;break;
case "/":
if(num2==0){
JOptionPane.showMessageDialog(this, "除数不能为0");
jtf2.requestFocus();
return;
}else{
num3=num1/num2;
break;
}
}
jtf3.setText(String.valueOf(num3));
}
if(ae.getSource()==jb2){
System.exit(0);
}
}
}
运行结果
//JAVA编程:四则运算(接收用户输入的2个操作数，和运算符)，计算之后，输出结果~~~~
import java.util.Scanner;
public class 四则运算 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.print("请输入第一个数字：");
int a = sc.nextInt();
System.out.print("请输入运算符号：");
String str = sc.next();
char ch = str.charAt(0);
System.out.print("请输入第二个数字：");
int b = sc.nextInt();
switch(ch)
{
case '+':
System.out.println(a+"+"+ b + "="+(a+b));
break;
case '-':
System.out.println(a+"-"+ b+ "="+(a-b));
break;
case '*':
System.out.println(a+"*"+ b+ "="+(a*b));
break;
case '/':
if(b==0){
System.out.println("被除数为零，运算无意义!");
break;
}
else {
System.out.println(a+"/"+ b+ " = "+(a/b));
break;
}
default:
System.out.println("运算符是无意义字符！");
break;
}
}
}
望采纳~~~~~~~~
