用java实现简单的计算机程序
1.该程序能实现加减乘除运算
2.界面的实现
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Calc extends JFrame implements ActionListener,KeyListener{
JTextField txtResult;
JButton btn0,btn1,btn2,btn3,btn4,btn5,btn6,btn7,btn8,btn9;
JButton btnAdd,btnSub,btnTimes,btnDiv,btnEquals,btnDot;
JButton btnClear,btnExit;
JPanel centerPanel,southPanel;
double num1=0,num2=0,result=0;
String opr= "+";
public Calc() {
setTitle("计算器2016");
txtResult = new JTextField("0.0");
//只读
// txtResult.setEditable(false);
centerPanel = new JPanel(new GridLayout(4,4,5,5));
southPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
add(txtResult,BorderLayout.NORTH);
txtResult.addKeyListener(this);
add(centerPanel);
btn0 = new JButton("0");
btn1 = new JButton("1");
btn2 = new JButton("2");
btn3 = new JButton("3");
btn4 = new JButton("4");
btn5 = new JButton("5");
btn6 = new JButton("6");
btn7 = new JButton("7");
btn8 = new JButton("8");
btn9 = new JButton("9");
btnAdd = new JButton("+");
btnSub = new JButton("-");
btnTimes = new JButton("*");
btnDiv = new JButton("/");
btnDot = new JButton(".");
btnEquals = new JButton("=");
centerPanel.add(btn7);
centerPanel.add(btn8);
centerPanel.add(btn9);
centerPanel.add(btnDiv);
centerPanel.add(btn4);
centerPanel.add(btn5);
centerPanel.add(btn6);
centerPanel.add(btnTimes);
centerPanel.add(btn1);
centerPanel.add(btn2);
centerPanel.add(btn3);
centerPanel.add(btnSub);
centerPanel.add(btn0);
centerPanel.add(btnDot);
centerPanel.add(btnEquals);
centerPanel.add(btnAdd);
add(southPanel,BorderLayout.SOUTH);
btnClear = new JButton("清除");
btnExit = new JButton("关闭");
southPanel.add(btnClear);
southPanel.add(btnExit);
//监听
btn0.addActionListener(this);
btn1.addActionListener(this);
btn2.addActionListener(this);
btn3.addActionListener(this);
btn4.addActionListener(this);
btn5.addActionListener(this);
btn6.addActionListener(this);
btn7.addActionListener(this);
btn8.addActionListener(this);
btn9.addActionListener(this);
btnAdd.addActionListener(this);
btnSub.addActionListener(this);
btnTimes.addActionListener(this);
btnDiv.addActionListener(this);
btnDot.addActionListener(this);
btnEquals.addActionListener(this);
btnClear.addActionListener(this);
btnExit.addActionListener(this);
setSize(300, 300);
setVisible(true);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new Calc();
}
public void actionPerformed(ActionEvent e) {
if(e.getSource()==btnClear){
txtResult.setText("0");
}else if(e.getSource()==btnExit){
System.exit(0);
}else if(e.getSource()==btn0){
setText("0");
}else if(e.getSource()==btn1){
setText("1");
}else if(e.getSource()==btn2){
setText("2");
}else if(e.getSource()==btn3){
setText("3");
}else if(e.getSource()==btn4){
setText("4");
}else if(e.getSource()==btn5){
setText("5");
}else if(e.getSource()==btn6){
setText("6");
}else if(e.getSource()==btn7){
setText("7");
}else if(e.getSource()==btn8){
setText("8");
}else if(e.getSource()==btn9){
setText("9");
}else if(e.getSource()==btnDot){
setText(".");
}else if(e.getSource()==btnAdd){
opr = "+";
operator();
//清空内容
txtResult.setText("");
}else if(e.getSource()==btnSub){
opr = "-";
operator();
//清空内容
txtResult.setText("");
}else if(e.getSource()==btnTimes){
opr = "*";
operator();
//清空内容
txtResult.setText("");
}else if(e.getSource()==btnDiv){
opr = "/";
operator();
//清空内容
txtResult.setText("");
}else if(e.getSource()==btnEquals){
operator();
txtResult.setText(result+"");
num1=num2=result=0;
}
}
public void setText(String s){
//获取文本框的值
String str = txtResult.getText().trim();
//如果文本框里面的值是0，那么初始化为空值
if(str.equals("" ) || Double.parseDouble(str)==0){
str = "";
}
str += s;
//设置文本框的值
txtResult.setText(str);
}
public void operator(){
if(txtResult.getText().equals("")){
num1=0;
}else{
num1 = Double.parseDouble(txtResult.getText().trim());
}
System.out.println("num1="+num1+";num2="+num2);
if(opr.equals("+")){
result = num1+num2;
}else if(opr.equals("-")){
result = num2-num1;
}else if(opr.equals("*")){
result = num1*num2;
}else if(opr.equals("/")){
result = num2/num1;
}
num2=num1;
}
String m_temp;
public void keyPressed(KeyEvent e) {
m_temp = txtResult.getText();
}
public void keyReleased(KeyEvent e) {
try{
Double.parseDouble(txtResult.getText());
}catch(Exception ex){
txtResult.setText(m_temp);
}
}
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
}
当然如果你是想在eclipse控制台输入输出，代码如下
import java.util.Scanner;
public class Dome1 {
private double n1;
private double n2;
private double result;
//加法方法
public static void add() {
Dome1 dome1 = new Dome1();
System.out.println("请输入第一个数");
Scanner scanner = new Scanner(System.in);
dome1.setN1(scanner.nextInt());
System.out.println("请输入第二个数");
dome1.setN2(scanner.nextInt());
dome1.setResult(dome1.getN1() + dome1.getN2());
System.out.println(dome1.getResult());
}
//减法方法
public static void sub() {
Dome1 dome1 = new Dome1();
System.out.println("请输入第一个数");
Scanner scanner = new Scanner(System.in);
dome1.setN1(scanner.nextInt());
System.out.println("请输入第二个数");
dome1.setN2(scanner.nextInt());
dome1.setResult(dome1.getN1() - dome1.getN2());
System.out.println(dome1.getResult());
}
//乘法方法
public static void mul() {
Dome1 dome1 = new Dome1();
System.out.println("请输入第一个数");
Scanner scanner = new Scanner(System.in);
dome1.setN1(scanner.nextInt());
System.out.println("请输入第二个数");
dome1.setN2(scanner.nextInt());
dome1.setResult(dome1.getN1() * dome1.getN2());
System.out.println(dome1.getResult());
}
//除法方法
public static void div() {
Dome1 dome1 = new Dome1();
System.out.println("请输入除数");
Scanner scanner = new Scanner(System.in);
dome1.setN1(scanner.nextInt());
System.out.println("请输入被除数数");
dome1.setN2(scanner.nextInt());
if (dome1.getN2() != 0) {
dome1.setResult(dome1.getN1() / dome1.getN2());
} else {
System.out.println("被除数不能为0，请重新输入");
dome1.setN2(scanner.nextInt());
dome1.setResult(dome1.getN1() / dome1.getN2());
}
System.out.println(dome1.getResult());
}
//判断用户需要的计算种类
public static void judge(){
Dome1 dome1 = new Dome1();
Scanner scanner = new Scanner(System.in);
System.out.println("您想要做什么类型的计算？加法请按“1”\t减法请按“2”\t乘法请按“3”\t除法请按“4”");
Integer i = scanner.nextInt();
if (i > 0 && i < 5 && i instanceof Integer) {
if (i == 1){
dome1.add();
}else if (i == 2){
dome1.sub();
}else if (i == 3){
dome1.mul();
}else if (i == 4){
dome1.div();
}
} else {
System.out.println("请输入1~4以内的数,请重试");
dome1.judge();
}
}
public static void main(String[] args) {
Dome1 dome1 = new Dome1();
dome1.judge();
}
public double getN1() {
return n1;
}
public void setN1(double n1) {
this.n1 = n1;
}
public double getN2() {
return n2;
}
public void setN2(double n2) {
this.n2 = n2;
}
public double getResult() {
return result;
}
public void setResult(double result) {
this.result = result;
}
}
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