本例实现一个带括号的GUI计算器，采用鼠标点击按钮输入。
Window.java
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Stack;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class Window {
public void window() {
JFrame frame=new JFrame();
frame.setTitle("计算器");
frame.setSize(505,640);
frame.setLocationRelativeTo(null);
frame.setResizable(false);
frame.setLayout(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextField tf=new JTextField(50);
tf.setSize(480,180);
tf.setBounds(10,10,480,180);
tf.setFont(new Font("黑体",Font.PLAIN,50));
tf.setEditable(false);
JButton btn1=new JButton("7");
btn1.setSize(80,80);
btn1.setBounds(10,210,80,80);
btn1.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn2=new JButton("8");
btn2.setSize(80,80);
btn2.setBounds(110,210,80,80);
btn2.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn3=new JButton("9");
btn3.setSize(80,80);
btn3.setBounds(210,210,80,80);
btn3.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn4=new JButton("+");
btn4.setSize(80,80);
btn4.setBounds(310,210,80,80);
btn4.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn5=new JButton("4");
btn5.setSize(80,80);
btn5.setBounds(10,310,80,80);
btn5.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn6=new JButton("5");
btn6.setSize(80,80);
btn6.setBounds(110,310,80,80);
btn6.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn7=new JButton("6");
btn7.setSize(80,80);
btn7.setBounds(210,310,80,80);
btn7.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn8=new JButton("-");
btn8.setSize(80,80);
btn8.setBounds(310,310,80,80);
btn8.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn9=new JButton("1");
btn9.setSize(80,80);
btn9.setBounds(10,410,80,80);
btn9.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn10=new JButton("2");
btn10.setSize(80,80);
btn10.setBounds(110,410,80,80);
btn10.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn11=new JButton("3");
btn11.setSize(80,80);
btn11.setBounds(210,410,80,80);
btn11.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn12=new JButton("x");
btn12.setSize(80,80);
btn12.setBounds(310,410,80,80);
btn12.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn13=new JButton("(");
btn13.setSize(80,80);
btn13.setBounds(10,510,80,80);
btn13.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn14=new JButton("0");
btn14.setSize(80,80);
btn14.setBounds(110,510,80,80);
btn14.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn15=new JButton(")");
btn15.setSize(80,80);
btn15.setBounds(210,510,80,80);
btn15.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn16=new JButton("/");
btn16.setSize(80,80);
btn16.setBounds(310,510,80,80);
btn16.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn17=new JButton("AC");
btn17.setSize(80,80);
btn17.setBounds(410,210,80,80);
btn17.setFont(new Font("黑体",Font.PLAIN,40));
JButton btn18=new JButton("Del");
btn18.setSize(80,80);
btn18.setBounds(410,310,80,80);
btn18.setFont(new Font("黑体",Font.PLAIN,30));
JButton btn19=new JButton(".");
btn19.setSize(80,80);
btn19.setBounds(410,410,80,80);
btn19.setFont(new Font("黑体",Font.PLAIN,50));
JButton btn20=new JButton("=");
btn20.setSize(80,80);
btn20.setBounds(410,510,80,80);
btn20.setFont(new Font("黑体",Font.PLAIN,50));
btn1.addActionListener(new ButtonHandler(tf));
btn2.addActionListener(new ButtonHandler(tf));
btn3.addActionListener(new ButtonHandler(tf));
btn4.addActionListener(new ButtonHandler(tf));
btn5.addActionListener(new ButtonHandler(tf));
btn6.addActionListener(new ButtonHandler(tf));
btn7.addActionListener(new ButtonHandler(tf));
btn8.addActionListener(new ButtonHandler(tf));
btn9.addActionListener(new ButtonHandler(tf));
btn10.addActionListener(new ButtonHandler(tf));
btn11.addActionListener(new ButtonHandler(tf));
btn12.addActionListener(new ButtonHandler(tf));
btn13.addActionListener(new ButtonHandler(tf));
btn14.addActionListener(new ButtonHandler(tf));
btn15.addActionListener(new ButtonHandler(tf));
btn16.addActionListener(new ButtonHandler(tf));
btn17.addActionListener(new ButtonHandler(tf));
btn18.addActionListener(new ButtonHandler(tf));
btn19.addActionListener(new ButtonHandler(tf));
btn20.addActionListener(new ButtonHandler(tf));
frame.add(tf);
frame.add(btn1);
frame.add(btn2);
frame.add(btn3);
frame.add(btn4);
frame.add(btn5);
frame.add(btn6);
frame.add(btn7);
frame.add(btn8);
frame.add(btn9);
frame.add(btn10);
frame.add(btn11);
frame.add(btn12);
frame.add(btn13);
frame.add(btn14);
frame.add(btn15);
frame.add(btn16);
frame.add(btn17);
frame.add(btn18);
frame.add(btn19);
frame.add(btn20);
frame.setVisible(true);
}
public static class ButtonHandler implements ActionListener{
public JTextField tf=new JTextField();
private Stack<Double> numberStack = null;
private Stack<Character> symbolStack = null;
public static boolean flag_symbol=false;
public static boolean flag_comma=true;
public static boolean flag_bracket=false;
public double calculate(String numStr) {
if (numStr.length() > 1 && !"=".equals(numStr.charAt(numStr.length() - 1) + "")) {
numStr += "=";
}
numberStack = new Stack<Double>();
symbolStack = new Stack<Character>();
StringBuffer temp = new StringBuffer();
for (int i = 0; i < numStr.length(); i++) {
char ch = numStr.charAt(i);
if (isNumber(ch)) temp.append(ch);
else {
String tempStr = temp.toString();
if (!tempStr.isEmpty()) {
double num = Double.parseDouble(tempStr);
numberStack.push(num);
temp = new StringBuffer();
}
while (!comparePri(ch) && !symbolStack.empty()) {
double b = numberStack.pop();
double a = numberStack.pop();
switch ((char) symbolStack.pop()) {
case '+':numberStack.push(a + b);break;
case '-':numberStack.push(a - b);break;
case 'x':numberStack.push(a * b);break;
case '/':numberStack.push(a / b);break;
default:break;
}
}
if (ch != '=') {
symbolStack.push(new Character(ch));
if (ch == ')') {
symbolStack.pop();
symbolStack.pop();
}
}
}
}
return numberStack.pop();
}
private boolean isNumber(char num) {
if (num >= '0' && num <= '9'||num=='.') return true;
else return false;
}
private boolean comparePri(char symbol) {
if (symbolStack.empty()) return true;
char top = (char) symbolStack.peek();
if (top == '(') return true;
switch (symbol) {
case '(': return true;
case 'x': {
if (top == '+' || top == '-') return true;
else return false;
}
case '/': {
if (top == '+' || top == '-') return true;
else return false;
}
case '+':return false;
case '-':return false;
case ')':return false;
case '=':return false;
default:break;
}
return true;
}
ButtonHandler(JTextField tf){
this.tf=tf;
}
public void actionPerformed(ActionEvent e) {
if(e.getActionCommand()=="7") {
tf.setText(tf.getText()+"7");
flag_symbol=true;
}
else if(e.getActionCommand()=="8") {
tf.setText(tf.getText()+"8");
flag_symbol=true;
}
else if(e.getActionCommand()=="9") {
tf.setText(tf.getText()+"9");
flag_symbol=true;
}
else if(e.getActionCommand()=="4") {
tf.setText(tf.getText()+"4");
flag_symbol=true;
}
else if(e.getActionCommand()=="5") {
tf.setText(tf.getText()+"5");
flag_symbol=true;
}
else if(e.getActionCommand()=="6") {
tf.setText(tf.getText()+"6");
flag_symbol=true;
}
else if(e.getActionCommand()=="1") {
tf.setText(tf.getText()+"1");
flag_symbol=true;
}
else if(e.getActionCommand()=="2") {
tf.setText(tf.getText()+"2");
flag_symbol=true;
}
else if(e.getActionCommand()=="3") {
tf.setText(tf.getText()+"3");
flag_symbol=true;
}
else if(e.getActionCommand()=="0") {
tf.setText(tf.getText()+"0");
flag_symbol=true;
}
else if(e.getActionCommand()==")"&&flag_bracket) {
tf.setText(tf.getText()+")");
flag_bracket=false;
}
else if(e.getActionCommand()=="+"&&flag_symbol) {
tf.setText(tf.getText()+"+");
flag_symbol=false;
flag_comma=true;
}
else if(e.getActionCommand()=="-"&&flag_symbol) {
tf.setText(tf.getText()+"-");
flag_symbol=false;
flag_comma=true;
}
else if(e.getActionCommand()=="x"&&flag_symbol) {
tf.setText(tf.getText()+"x");
flag_symbol=false;
flag_comma=true;
}
else if(e.getActionCommand()=="/"&&flag_symbol) {
tf.setText(tf.getText()+"/");
flag_symbol=false;
flag_comma=true;
}
else if(e.getActionCommand()=="("&&!flag_bracket) {
tf.setText(tf.getText()+"(");
flag_bracket=true;
}
else if(e.getActionCommand()=="."&&flag_comma) {
tf.setText(tf.getText()+".");
flag_comma=false;
}
else if(e.getActionCommand()=="AC") tf.setText("");
else if(e.getActionCommand()=="Del") {
String str=tf.getText();
str=str.substring(0, str.length()-1);
tf.setText(str);
}
else if(e.getActionCommand()=="=") {
String str=tf.getText();
str=str+"=";
double result=calculate(str);
if(result==(int)result||Math.abs(result-(int)result)<1e-8) tf.setText((int)result+"");
else tf.setText(result+"");
}
}
}
public static void main(String args[]) {
Window window=new Window();
window.window();
}
}
运行效果如下：
