java：编写一个计算器小程序，要求可以做加减乘除运算

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener{
private static final long serialVersionUID = 8199443193151152362L;
private JButton bto_s=new JButton("sqrt"),bto_zf=new JButton("+/-"),bto_ce=new JButton("CE"),bto_c=new JButton("C"),bto_7=new JButton("7"),
bto_8=new JButton("8"),bto_9=new JButton("9"),bto_chu=new JButton("/"),bto_4=new JButton("4"),bto_5=new JButton("5"),
bto_6=new JButton("6"),bto_cheng=new JButton("*"),bto_1=new JButton("1"),bto_2=new JButton("2"),bto_3=new JButton("3"),
bto_jian=new JButton("-"),bto_0=new JButton("0"),bto_dian=new JButton("."),bto_deng=new JButton("="),bto_jia=new JButton("+");
JButton button[]={bto_s,bto_zf,bto_ce,bto_c,bto_7,bto_8,bto_9,bto_chu,bto_4,bto_5,bto_6,bto_cheng,bto_1,bto_2,bto_3,bto_jian,
bto_0,bto_dian,bto_deng,bto_jia};
private JTextField text_double;// = new JTextField("0");
private String operator = "="; //当前运算的运算符
private boolean firstDigit = true; // 标志用户按的是否是整个表达式的第一个数字,或者是运算符后的第一个数字
private double resultNum = 0.0; // 计算的中间结果
private boolean operateValidFlag = true; //判断操作是否合法
public Calculator()
{
super("Calculator");
this.setBounds(300, 300, 300, 300);
this.setResizable(false);
this.setBackground(Color.orange);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.getContentPane().setLayout(new BorderLayout());//设置布局
text_double=new JTextField("0",20);//设置文本区
text_double.setHorizontalAlignment(JTextField.RIGHT);//设置水平对齐方式未右对齐
this.getContentPane().add(text_double,BorderLayout.NORTH);//将文本区添加到Content北部
JPanel panel=new JPanel(new GridLayout(5,4));//在内容窗口添加一个网格布局
this.getContentPane().add(panel);//添加panel面板
for(int i=0;i panel.add(button[i]);

for(int i=0;i button[i].addActionListener(this);//为按钮注册
text_double.setEditable(false);//文本框不可编辑
text_double.addActionListener(this);//

this.setVisible(true);
}
public void actionPerformed(ActionEvent e)//
{
String c= e.getActionCommand();//返回与此动作相关的命令字符串。
System.out.println("##########command is "+c);
if(c.equals("C")){
handleC(); //用户按了“C”键
}
else if (c.equals("CE")) // 用户按了"CE"键
{
text_double.setText("0");
}
else if ("0123456789.".indexOf(c) >= 0) // 用户按了数字键或者小数点键
{
handleNumber(c); // handlezero(zero);
} else //用户按了运算符键
{
handleOperator(c);
}
}
private void handleC() // 初始化计算器的各种值
{
text_double.setText("0");
firstDigit = true;
operator = "=";
}
private void handleNumber(String button) {
if (firstDigit)//输入的第一个数字
{
text_double.setText(button);
} else if ((button.equals(".")) && (text_double.getText().indexOf(".") < 0))//输入的是小数点，并且之前没有小数点，则将小数点附在结果文本框的后面
//如果字符串参数作为一个子字符串在此对象中出现，则返回第一个这种子字符串的第一个字符的索引；如果它不作为一个子字符串出现，则返回 -1
{
text_double.setText(text_double.getText() + ".");
} else if (!button.equals("."))// 如果输入的不是小数点，则将数字附在结果文本框的后面
{
text_double.setText(text_double.getText() + button);
}
// 以后输入的肯定不是第一个数字了
firstDigit = false;
}
private void handleOperator(String button) {

if (operator.equals("/")) {
// 除法运算
// 如果当前结果文本框中的值等于0
if (getNumberFromText() == 0.0){
// 操作不合法
operateValidFlag = false;
text_double.setText("除数不能为零");
} else {
resultNum /= getNumberFromText();
}
} else if (operator.equals("+")){
// 加法运算
resultNum += getNumberFromText();
} else if (operator.equals("-")){
// 减法运算
resultNum -= getNumberFromText();
} else if (operator.equals("*")){
// 乘法运算
resultNum *= getNumberFromText();
} else if (operator.equals("sqrt")) {
// 平方根运算
if(getNumberFromText()<0){
operateValidFlag = false;
text_double.setText("被开方数不能为负数");}
else
resultNum = Math.sqrt(resultNum);
}
else if (operator.equals("+/-")){
// 正数负数运算
resultNum = resultNum * (-1);
} else if (operator.equals("=")){
// 赋值运算
resultNum = getNumberFromText();
}
if (operateValidFlag) {
// 双精度浮点数的运算
long t1;
double t2;
t1 = (long) resultNum;
t2 = resultNum - t1;
if (t2 == 0) {
text_double.setText(String.valueOf(t1));
} else {
text_double.setText(String.valueOf(resultNum));
}
}
operator = button; //运算符等于用户按的按钮
firstDigit = true;
operateValidFlag = true;
}
private double getNumberFromText() //从结果的文本框获取数字
{
double result = 0;
try {
result = Double.valueOf(text_double.getText()).doubleValue(); // ValueOf()返回表示指定的 double 值的 Double 实例
} catch (NumberFormatException e){
}
return result;
}
public static void main(final String[] args) {
new Calculator();
}
}

kankan我的

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.math.BigDecimal;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class TestCalc implements ActionListener {
JFrame jf = new JFrame("计算器");
JPanel jp = new JPanel();
JTextField jtf = new JTextField("0.", 200);
JButton[] jb = new JButton[20];
private int tag = 0;
private double a;
private double b;
private String operator;
StringBuilder sb1 = new StringBuilder();
StringBuilder sb2 = new StringBuilder();

public TestCalc() {

jf.add(jtf, BorderLayout.NORTH);
// jtf.requestFocus();
jtf.setEditable(false);
jtf.setCaretPosition(jtf.getText().length() - 1);
jf.add(jp);
jp.setLayout(new GridLayout(5, 4, 4, 4));
String[] str = { "Back", "CE", "C", "+", "7", "8", "9", "-", "4", "5",
"6", "*", "1", "2", "3", "/", "0", "+/-", ".", "=" };
int i = 0;
for (i = 0; i < str.length; i++) {
jb[i] = new JButton(str[i]);

jp.add(jb[i]);
jb[i].addActionListener(this);
}

jf.setSize(300, 240);
// jf.setLocation(300,200);
jf.setLocationRelativeTo(null);
jf.setVisible(true);
// jf.pack();//自动调整大小；
jf.setResizable(false);// 不允许别人调大小；
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public static void main(String[] args) {

TestCalc tc = new TestCalc();

}

public void actionPerformed(ActionEvent e) {

String command = e.getActionCommand();
if (command.matches("^[[0-9].]$")) {
if (tag == 0) {
sb1.append(command);
jtf.setText(sb1.substring(0));
} else {
sb2.append(command);
jtf.setText(sb2.substring(0));
}

} else if (command.matches("^[-/*+]$")) {
tag = 1;
operator = command;

} else {
if (command.matches("=")) {
String str1 = sb1.substring(0);
String str2 = sb2.substring(0);
if (str1 == null) {
a = 0.0;
} else {
a = Double.parseDouble(str1);
}
if (str2 == null) {
b = 0.0;
} else {
b = Double.parseDouble(str2);
}

if (operator.equals("+")) {
jtf.setText("" + (a + b));
} else if (operator.equals("-")) {
BigDecimal bd1 = new BigDecimal(Double.toString(a)); // 必须使用String做参数才可以精确运算
BigDecimal bd2 = new BigDecimal(Double.toString(b));
Double yu1 = bd1.subtract(bd2).doubleValue();
jtf.setText("" + (yu1));
} else if (operator.equals("*")) {
jtf.setText("" + (a * b));
} else if (operator.equals("/")) {
BigDecimal bd1 = new BigDecimal(Double.toString(a)); // 必须使用String做参数才可以精确运算
BigDecimal bd2 = new BigDecimal(Double.toString(b));
Double yu1 = bd1.divide(bd2).doubleValue();
jtf.setText("" + yu1);
}
tag = 0;
sb1.delete(0, sb1.length());
sb2.delete(0, sb2.length());
} else if (command.matches("C")) {
tag = 0;
sb1.delete(0, sb1.length());
sb2.delete(0, sb2.length());
jtf.setText("0.");
jtf.setCaretPosition(jtf.getText().length() - 1);
} else if (command.matches("CE")) {
tag = 0;
sb2.delete(0, sb2.length());
jtf.setText(sb1.substring(0));
} else if (command.matches("Back")) {//Back功能键的实现；
if (tag == 0) {
sb1.deleteCharAt(sb1.length() - 1);
jtf.setText(sb1.substring(0));
} else {
sb2.deleteCharAt(sb2.length() - 1);
jtf.setText(sb2.substring(0));
}

} else if (command.matches("\\+/-")) {
if (tag == 0) {
if(sb1.substring(0,1).equals("-")){
sb1.replace(0,1,"+");
}else{
sb1.insert(0, "-");
}

jtf.setText(sb1.substring(0));
} else {
if(sb2.substring(0,1).equals("-")){
sb2.replace(0,1,"+");
}else{
sb2.insert(0, "-");
}
jtf.setText(sb2.substring(0));
}

}else {

}
}
}

}

这是我做的小计算器，你看下，可以实现加减乘除。觉得好就采纳，谢谢啦。

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class calculate
{
public static void main(String[] args) {
jxframe kj=new jxframe();
kj.setVisible(true);
kj.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
class jxframe extends JFrame
{
JTextField w;
private boolean pd;
private String bj;
private double result;
public jxframe()
{
setTitle("计算器");
pd=true;
bj="=";
result=0;
w=new JTextField(20);
add(w,"North");
add(new m(),"Center");
pack();

}
class m extends JComponent
{
public m()
{
setLayout(new GridLayout(4,4));
addbutton("7",new sz());
addbutton("8",new sz());
addbutton("9",new sz());
addbutton("/",new jx());
addbutton("4",new sz());
addbutton("5",new sz());
addbutton("6",new sz());
addbutton("*",new jx());
addbutton("1",new sz());
addbutton("2",new sz());
addbutton("3",new sz());
addbutton("+",new jx());
addbutton("0",new sz());
addbutton(".",new sz());
addbutton("=",new jx());
addbutton("-",new jx());
}
public void addbutton(String name,ActionListener e)
{
JButton an=new JButton(name);
an.addActionListener(e);
add(an);
}
class sz implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String sb=e.getActionCommand();
if(pd)
{
w.setText("");
pd=false;
}
w.setText(w.getText()+sb);
}
}
class jx implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String jb=e.getActionCommand();
if(pd)
{
jb.equals("-");
w.setText(jb);
pd=false;
}
else{
js(Double.parseDouble(w.getText()));
bj=jb;
pd=true;
}
}
}
public void js(double jsb)
{
if(bj.equals("/")) result/=jsb;
if(bj.equals("*")) result*=jsb;
if(bj.equals("+")) result+=jsb;
if(bj.equals("-")) result-=jsb;
if(bj.equals("=")) result=jsb;
w.setText(""+result);
}
}
}

代码如下：
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Accumulator extends JFrame implements ActionListener,ItemListener{

public double result=0;
static String is="+";
JTextField jt1 = new JTextField(10);

JTextField jt2 = new JTextField(10);

JTextField jt3 = new JTextField(10);

JComboBox jcb = new JComboBox();

JButton jb = new JButton("=");
public Accumulator(){
JPanel jp = new JPanel();
jp.setLayout(new FlowLayout());

jcb.addItemListener(this);
jcb.addItem("+");
jcb.addItem("-");
jcb.addItem("*");
jcb.addItem("/");

jb.addActionListener(this);

jp.add(jt1);
jp.add(jcb);
jp.add(jt2);
jp.add(jb);
jp.add(jt3);

this.setTitle("简易计算器");
this.add(jp);
this.setBounds(400, 350, 500, 300);
this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
this.setVisible(true);
}

@Override
public void actionPerformed(ActionEvent ae) {
if(ae.getSource()==jb){
if(is.equals("+")){
result =Double.parseDouble(jt1.getText())+Double.parseDouble(jt2.getText());
jt3.setText(String.valueOf(result));
}
if(is.equals("-")){
result =Double.parseDouble(jt1.getText())-Double.parseDouble(jt2.getText());
jt3.setText(String.valueOf(result));
}
if(is.equals("*")){
result =Double.parseDouble(jt1.getText())*Double.parseDouble(jt2.getText());
jt3.setText(String.valueOf(result));
}
if(is.equals("/")){
result =Double.parseDouble(jt1.getText())/Double.parseDouble(jt2.getText());
jt3.setText(String.valueOf(result));
}
}
}

public static void main(String [] args){
Accumulator ac = new Accumulator();
}

@Override
public void itemStateChanged(ItemEvent ie) {
is =(String)ie.getItem();
}
}