简单写了下，代码如下请参照：
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/**
* 计算器类
*
* @author Administrator
*
*/
public class Calculator extends JFrame implements ActionListener {
private static final long serialVersionUID = 3868243398506940702L;
// 文本框
private JTextField result;
// 按钮数组
private JButton[] buttons;
// 按钮文本
private final String[] characters = { "7", "8", "9", "/", "4", "5", "6",
"*", "1", "2", "3", "-", "0", ".", "=", "+" };
// 是否为第一个输入的数字
private boolean isFirstDigit = true;
// 运算结果
private double resultNum = 0.0;
// 运算符
private String operator = "=";
public Calculator(String title) {
// 设置标题栏
super(title);
// 初始化各组件
init();
// 注册各组件监听器
registerListener();
// 显示窗体
setVisible(true);
}
/**
* 初始化各组件
*/
private void init() {
// 常用属性初始化
setSize(220, 200);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
/* 文本框对象初始化 */
result = new JTextField("0");
// 文本右对齐
result.setHorizontalAlignment(JTextField.RIGHT);
// 设置是否可编辑
result.setEditable(false);
/* 按钮初始化 */
buttons = new JButton[characters.length];
for (int i = 0; i buttons.length; i++) {
buttons[i] = new JButton(characters[i]);
buttons[i].setFocusable(false); // 不允许按钮定位焦点
}
/* 将文本框与按钮添加到窗体中 */
add(result, BorderLayout.NORTH);
JPanel pnl = new JPanel(new GridLayout(4, 4, 5, 5));
for (JButton jButton : buttons) {
pnl.add(jButton);
}
add(pnl);
this.getContentPane().setFocusable(true);
}
/**
* 注册监听器
*/
private void registerListener() {
for (JButton jButton : buttons) {
jButton.addActionListener(this);
}
// 注册键盘事件
this.getContentPane().addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
String text = String.valueOf(e.getKeyChar());
if (Character.isDigit(text.charAt(0)) || ".".equals(text)) { // 数字或小数点
handleNumber(text);
} else if ("+-*/=".indexOf(text) != -1) { // 运算符
handleOperator(text);
} else if (e.getKeyCode() == 8) { // 退格键
String tmp = result.getText().trim();
if (tmp.length() == 1) {
result.setText("0");
isFirstDigit = true;
} else {
result.setText(tmp.substring(0, tmp.length() - 1));
}
}
}
});
}
@Override
public void actionPerformed(ActionEvent e) {
JButton btn = (JButton) e.getSource();
String text = btn.getText().trim();
if (Character.isDigit(text.charAt(0)) || ".".equals(text)) { // 处理数字和小数点
handleNumber(text);
} else { // 处理运算符
handleOperator(text);
}
}
/**
* 处理数字和小数点
*
* @param text
*/
private void handleNumber(String text) {
if (isFirstDigit) { // 第一次输入
if (".".equals(text)) {
this.result.setText("0.");
} else {
this.result.setText(text);
}
} else if ("0".equals(text) "0".equals(this.result.getText())) {
isFirstDigit = true;
return;
} else if (".".equals(text) this.result.getText().indexOf(".") == -1) {
this.result.setText(this.result.getText() + ".");
} else if (!".".equals(text)) {
this.result.setText(this.result.getText() + text);
}
isFirstDigit = false;
}
/**
* 处理运算符
*
* @param text
*/
private void handleOperator(String text) {
switch (operator) { // 处理各项运算 适用于JDK1.7版本的
case "+":
resultNum += Double.parseDouble(this.result.getText());
break;
case "-":
resultNum -= Double.parseDouble(this.result.getText());
break;
case "*":
resultNum *= Double.parseDouble(this.result.getText());
break;
case "/":
resultNum /= Double.parseDouble(this.result.getText());
break;
case "=":
resultNum = Double.parseDouble(this.result.getText());
break;
}
// 将文本框的值修改为运算结果
this.result.setText(String.valueOf(resultNum));
// 将点击的运算符放入operator保存
operator = text;
// 下一个数字第一次点击
isFirstDigit = true;
}
public static void main(String[] args) {
new Calculator("My Calculator");
}
}
运行结果如下：
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class Calculator extends JFrame{
private float op1,op2;//定义两个变量存放需要运算的值
private String str="";//定义str去和text进行交叉赋值
private String opr,co;//opr存放符合，co用来存放复制的内容
private double re;//用来存放运算的结果
private boolean bo=false;//是否进行了+-*/运算
private boolean btime=false;//时间开关
Container contentpane=this.getContentPane();
JPanel panel1=new JPanel(new BorderLayout()),
panel2=new JPanel(new FlowLayout()),
panel3=new JPanel(new GridLayout(4,5)),
panel4=new JPanel(new BorderLayout()),
panel5=new JPanel(new BorderLayout());
//菜单栏
JMenuBar menubar=new JMenuBar();
JMenu edit=new JMenu("编辑(E)"),
find=new JMenu("查看(V)"),
help=new JMenu("帮助(H)");
JMenuItem copy=new JMenuItem("复制(C)",'C'),
paste=new JMenuItem("粘贴(P)",'P'),
standard=new JMenuItem("标准型(T)",'T'),
science=new JMenuItem("科学型(S)",'S'),
numarray=new JMenuItem("数字分组(I)",'I'),
helptopic=new JMenuItem("帮助主题(H)",'H'),
aboutcal=new JMenuItem("关于计算器(A)",'A');
//输入文本框
JTextField text=new JTextField(25);
//数字键
JButton one=new JButton("1"),
two=new JButton("2"),
three=new JButton("3"),
four=new JButton("4"),
five=new JButton("5"),
six=new JButton("6"),
seven=new JButton("7"),
eight=new JButton("8"),
nine=new JButton("9"),
zero=new JButton("0");
//功能键
JButton division=new JButton("/"),
multiply=new JButton("*"),
addition=new JButton("+"),
subtration=new JButton("-"),
sqrt=new JButton("sqrt"),
residual=new JButton("%"),
sign=new JButton("+/-"),
dot=new JButton("."),
reciprocal=new JButton("1/X"),
amount=new JButton("="),
backspace=new JButton("Backspace"),
ce=new JButton("CE"),
c=new JButton("C"),
time=new JButton("time");
public Calculator() {
contentpane.setLayout(new BorderLayout());
//textField文本从右边开始写
text.setHorizontalAlignment(SwingConstants.RIGHT);
text.setText("0.");
//菜单栏添加
edit.add(copy);
edit.add(paste);
find.add(standard);
find.add(science);
find.addSeparator();
find.add(numarray);
help.add(helptopic);
help.addSeparator();
help.add(aboutcal);
//把组件添加至容器中
menubar.add(edit);
menubar.add(find);
menubar.add(help);
panel1.add(menubar,"North");
panel1.add(text,"West");
//添加数字、功能键至panel2、panel3
panel2.add(backspace);
panel2.add(ce);
panel2.add(c);
panel2.add(time);
panel3.add(seven);
panel3.add(eight);
panel3.add(nine);
panel3.add(division);
panel3.add(sqrt);
panel3.add(four);
panel3.add(five);
panel3.add(six);
panel3.add(multiply);
panel3.add(residual);
panel3.add(one);
panel3.add(two);
panel3.add(three);
panel3.add(subtration);
panel3.add(reciprocal);
panel3.add(zero);
panel3.add(sign);
panel3.add(dot);
panel3.add(addition);
panel3.add(amount);
panel4.add(panel2,"North");
panel4.add(panel3,"West");
panel5.add(panel1,"North");
panel5.add(panel4,"West");
contentpane.add(panel5,"North");
//事件
//助记符
edit.setMnemonic('E');
find.setMnemonic('V');
help.setMnemonic('H');
//快捷键
KeyStroke kcopy=KeyStroke.getKeyStroke(KeyEvent.VK_C,Event.CTRL_MASK);
copy.setAccelerator(kcopy);
KeyStroke kpaste=KeyStroke.getKeyStroke(KeyEvent.VK_V,Event.CTRL_MASK);
paste.setAccelerator(kpaste);
//0-9、.的显示事件
actionlistener1 al1=new actionlistener1();
one.addActionListener(al1);
two.addActionListener(al1);
three.addActionListener(al1);
four.addActionListener(al1);
five.addActionListener(al1);
six.addActionListener(al1);
seven.addActionListener(al1);
eight.addActionListener(al1);
nine.addActionListener(al1);
//小数点的ActionListener事件
dot.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int count;
count=str.length();
//1.第一位就为.时改变text中内容为："0."
if(count==0){
str="0.";
text.setText(str);
}
//2.不可以重复按"."
else {if(!str.contains(".")){
str+=".";
text.setText(str);
}
else
System.out.println("您再点的话，输入的将不再是小数了！");
}
}
});
//如果第一位是0那么第二位就不可以为0
zero.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int count;
count=str.length();
if(bo){
if(!(str.contains("0")count==1)){
str="";
str+="0";
text.setText(str);
}else
System.out.println("您再点的话，输入的将不再是数字了！");
}
else{
if(!(str.contains("0")count==1)){
str+="0";
text.setText(str);
}else
System.out.println("您再点的话，输入的将不再是数字了！");
}
bo=false;
}
});
//+、-、*、/、%运算
actionlistener3 al3=new actionlistener3();
addition.addActionListener(al3);
subtration.addActionListener(al3);
multiply.addActionListener(al3);
division.addActionListener(al3);
residual.addActionListener(al3);
//CE和C清空按钮时间
actionlistener2 al2=new actionlistener2();
ce.addActionListener(al2);
c.addActionListener(al2);
//退格键
backspace.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int count;
count=str.length()-1;
if(bo==false){
if(count=0){
str=str.substring(0,count);
text.setText(str);
}
else
text.setText("0.");
}else
System.out.println("您现在正进行法则运算！");
}
});
//求平方根
sqrt.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int count;
count=str.length();
if(count!=0){
op1=Float.parseFloat(text.getText());
re=Math.sqrt(op1);
String str1=String.valueOf(re);
text.setText(str1);
str="";
}
else
System.out.println("您现在的按sqrt键毫无意义");
}
});
//求倒数
reciprocal.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int count;
count=str.length();
if(count!=0){
op1=Float.parseFloat(text.getText());
if(op1!=0){
re=1/op1;
String str1=String.valueOf(re);
text.setText(str1);
str=str1;
}
else{
text.setText("除数不可以为0的");
str="";
}
}
else
System.out.println("您现在的按1/X键毫无意义");
}
});
//=事件
amount.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
op2=Float.parseFloat(str);
//需判断进行那种运算法则
if(opr=="+"){//加法运算
re=op1+op2;
String str1=String.valueOf(re);
text.setText(str1);
str=String.valueOf(re);
}else{
if(opr=="-"){//减法运算
re=op1-op2;
String str1=String.valueOf(re);
text.setText(str1);
str=String.valueOf(re);
}else{
if(opr=="*"){//乘法运算
re=op1*op2;
String str1=String.valueOf(re);
text.setText(str1);
str=String.valueOf(re);
}else{
if(opr=="/"op2!=0){//除法运算
re=op1/op2;
String str1=String.valueOf(re);
text.setText(str1);
str=String.valueOf(re);
}else{
if(opr=="%"){//取余运算
re=op1%op2;
String str1=String.valueOf(re);
text.setText(str1);
str="";
}
else if(op2==0){
text.setText("除数不可以为0的");
str="";
}
}
}
}
}
//打印看看
System.out.print(op1);
System.out.print(opr);
System.out.print(op2+"=");
System.out.print(re);
System.out.println();
}
});
//复制事件
copy.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int count;
count=str.length();
if(count!=0){
co=text.getText();
}
else
System.out.println("没有可复制的对象");
}
});
//粘贴事件
paste.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
str=co;
text.setText(str);
}
});
//时间事件
time.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
if(btime==false){
String st=(new Date()).toString();
text.setText(st);
str="";
btime=true;
}
else{
text.setText(str);
btime=false;
}
}
});
//+/-事件
sign.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int a=Integer.valueOf(str);
a=a*(-1);
str=String.valueOf(a);
text.setText(str);
}
});
}
//定义1-9按钮在text中显示的内部类
class actionlistener1 implements ActionListener{
public void actionPerformed(ActionEvent e){
JButton button=(JButton)e.getSource();
String btext=button.getText();
//如果第一位为0再输入其他非零的整数时将零忽略
if(bo){
if(str.indexOf("0")==0str.length()==1){
str="";
str+=btext;
text.setText(str);
}else{
str="";
str+=btext;
text.setText(str);}
}else{
if(str.indexOf("0")==0str.length()==1){
str="";
str+=btext;
text.setText(str);
}else{
str+=btext;
text.setText(str);
}
}
bo=false;
}
}
//定义清空text中内容的内部类
class actionlistener2 implements ActionListener{
public void actionPerformed(ActionEvent e){
str="";
text.setText("0.");
}
}
//定义+、-、*、/、%运算的内部类
class actionlistener3 implements ActionListener{
public void actionPerformed(ActionEvent e){
int count;
count=str.length();
if(count!=0){
JButton button=(JButton)e.getSource();
opr=button.getText();
op1=Float.parseFloat(str);
bo=true;
}
else
System.out.println("您现在的按键毫无意义！");
}
}
public static void main(String[] args){
Calculator cc=new Calculator();
cc.pack();
cc.setResizable(false);//不可最大化
cc.setVisible(true);
cc.setTitle("计算器");
cc.setDefaultCloseOperation(EXIT_ON_CLOSE);
Dimension scmsize=Toolkit.getDefaultToolkit().getScreenSize();
int w=cc.getSize().width;
int h=cc.getSize().height;
int x=(scmsize.width-w)/2;
int y=(scmsize.height-h)/2;
cc.setLocation(x, y);
}
}
学java的时候自己编的，很简单，能够连续输入计算式后进行计算
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
/**简易计算器，能够进行简单的计算
*
* @see 2008.12.9
*/
public class CalculatorA
implements ActionListener{
private JFrame frame;
private JTextField field;
private JButton[] allButtons;
private JButton clearButton;
// private JButton backButton;
String result="";//保存结果
StringBuilder sb = new StringBuilder();//保存要进行的计算式
int x = 0; //用来判断上一次的事件类型
String str = "123+456-789*0.=/";
ArrayListString arrayList = new ArrayListString();//保存计算式，通过方法进行运算
public CalculatorA(){
frame = new JFrame("我的计算器v1.1");
frame.setLocation(300,300);
field = new JTextField(25);
allButtons = new JButton[16];
for(int i=0;iallButtons.length;i++){
allButtons[i]= new JButton(str.substring(i,i+1));
}
clearButton = new JButton("CLEAR");
// backButton = new JButton("——");
init();
setFondAndColor();
addEventHander();
}
public void init(){
frame.setLayout(new BorderLayout());
JPanel northPanel = new JPanel();
JPanel centerPanel = new JPanel();
JPanel southPanel = new JPanel();
northPanel.setLayout(new FlowLayout());
centerPanel.setLayout(new GridLayout(4,4));
southPanel.setLayout(new FlowLayout());
northPanel.add(field);
for(int i=0;iallButtons.length;i++){
centerPanel.add(allButtons[i]);
}
southPanel.add(clearButton);
//southPanel.add(backButton);
frame.add(northPanel,BorderLayout.NORTH);
frame.add(centerPanel,BorderLayout.CENTER);
frame.add(southPanel,BorderLayout.SOUTH);
}
//设置输入字体
public void setFondAndColor(){
field.setFont(new Font("宋体",Font.BOLD,24));
field.setBackground(new Color(100,200,200));
field.setForeground(Color.RED);
//设置字体从右起始
field.setHorizontalAlignment(JTextField.RIGHT);
}
public void showMi(){
frame.pack();
frame.setResizable(false);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void addEventHander(){
for(int i=0;iallButtons.length;i++){
allButtons[i].addActionListener(this);
}
clearButton.addActionListener(this);
// backButton.addActionListener(this);
}
@Override
public void actionPerformed(ActionEvent e) {
String str = e.getActionCommand();//取得当前事件返回的值
if("0123456789.".indexOf(str)!=-1){
if(x == 0){ //当x为0时表示还没有进行输入
result=str;
sb.append(str);
field.setText(str);
x = 1;
}
else if(x == 1){
result = result +str;
sb.append(str);
field.setText(result);
x = 1;
}
else if(x == 2){
sb.delete(0,sb.length());
result = result+str;
sb.append(str);
field.setText(result);
x = 1;
}
else if(x == 3){
result = str;
sb.delete(0,sb.length());
arrayList.clear();
field.setText(str);
sb.append(str);
field.setText(str);
x = 1;
}
else if(x == 4){
result ="";
sb.delete(0,sb.length());
arrayList.clear();
result = str;
sb.append(str);
field.setText(str);
x = 1;
}
else{
result = result +str;
sb.append(str);
field.setText(result);
x = 1;
}
}
else if("+*-/".indexOf(str)!=-1){
if(x == 0){
field.setText("");
x = 2;
}
else if(x == 1){
result = result + str;
arrayList.add(sb.toString());
arrayList.add(str);
sb.append(str);
field.setText(result);
x = 2;
}
else if(x == 2){
x = 2;
}
else if(x == 3){
field.setText(result+str);
arrayList.add(result);
arrayList.add(str);
result = result+str;
x = 2;
}
else if(x == 4){
result ="";
sb.delete(0,sb.length());
arrayList.clear();
x = 2;
}
else{
field.setText(result+str);
arrayList.add(result);
arrayList.add(str);
result = result+str;
x = 2;
}
}
else if("=".equals(str)){
if(x == 0){
field.setText("0");
arrayList.clear();
result = "0";
x = 3;
}
else if(x == 1){
try{
arrayList.add(sb.toString());
arrayList = getResult(arrayList);
result = arrayList.get(0);
field.setText(result);
arrayList.clear();
x = 3;
}catch(Exception e1){
field.setText("数据格式异常");
x = 0;
}
}
else if(x == 2){
field.setText("数据格式错误.....");
arrayList.clear();
x = 0;
}
else if(x == 3){
field.setText(result);
x = 3;
}
else if(x == 4){
result ="";
sb.delete(0,sb.length());
arrayList.clear();
x = 3;
}
else {
try{
arrayList.add(sb.toString());
arrayList = getResult(arrayList);
result = arrayList.get(0);
field.setText(result);
arrayList.clear();
x = 3;
}catch(Exception e1){
field.setText("数据格式异常");
x = 0;
}
}
}
else if("CLEAR".equals(str)){
arrayList.clear();
field.setText("0");
arrayList.add("0");
x = 4;
}
else{
if(result.length()1){
result = result.substring(0,result.length()-1);
if(sb.length()0){
sb.delete(sb.length()-1,sb.length());
}
else {
sb.delete(0,1);
}
field.setText(result);
x = 5;
}
else{
result = "";
sb.delete(0,sb.length());
arrayList.clear();
field.setText("0");
x = 0;
}
}
}
public static ArrayListString getResult(ArrayListString list){
String res = null;
String[] s = {"/","*","-","+"};
int i=0;
if(list.size()1){
for(;is.length;){
if(s[i].equals("/")){
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))/Double.parseDouble(list.get(j+1)));
//本地的数据格式
NumberFormat nf = NumberFormat.getInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
else if(s[i].equals("*")){
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))*Double.parseDouble(list.get(j+1)));
NumberFormat nf = NumberFormat.getInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
else if(s[i].equals("-")){
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))-Double.parseDouble(list.get(j+1)));
NumberFormat nf = NumberFormat.getNumberInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
else {
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))+Double.parseDouble(list.get(j+1)));
NumberFormat nf = NumberFormat.getInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
}
}
return list;
}
//对数字字符串进行排除不必要符号
public static String getChange(String res){
String s_temp = "";
char[] c = new char[res.length()];
for(int k=0;kc.length;k++){
c[k] = res.charAt(k);
}
for(int k=0;kc.length;k++){
if((c[k]= '0' c[k]= '9')|| c[k] == '.'){
s_temp += c[k];
}
}
return s_temp;
}
public static void main(String[] args){
new CalculatorA().showMi();
}
}
这段代码对你有帮助
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。MyCalculator 继承于 JFrame，是计算器的界面
*/
public class MyCalculator 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 MyCalculator(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());
MyCalculator frame = new MyCalculator("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);
}
}
