简易计算器
package org.tarena.day01;import java.awt.BorderLayout;import java.awt.FlowLayout;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JTextField;public class CalculatorDemo implements ActionListener { static boolean append = true; JTextField jt = new JTextField(21); //简单计算器 public void makeCalculator() { JFrame jf = new JFrame("CalculatorDemo"); JPanel one = new JPanel(); JPanel two = new JPanel(); String[] str = { "BackS", "CE", "cir", "+/-", "7", "8", "9", "/", "4", "5", "6", "*", "1", "2", "3", "-", "0", ".", "=", "+" }; // 添加一个JPanel 和一个JLabel one.setLayout(new FlowLayout()); one.add(jt); two.setLayout(new GridLayout(5, 4)); for (int i = 0; i < 20; i++) { JButton jbut = new JButton(str); jbut.addActionListener(this); two.add(jbut); } jf.add(one, BorderLayout.NORTH); jf.add(two, BorderLayout.CENTER); jt.setEditable(false); jf.setSize(250, 200); jf.setLocation(450, 500); jf.setVisible(true); jf.setResizable(false); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } String num1 = "0"; String operator = "+"; public void actionPerformed(ActionEvent e) { String comm = e.getActionCommand(); if ("0123456789".indexOf(comm) != -1) {//也可以用正则验证 if (append) {// 追加 String s = jt.getText(); jt.setText(s + comm); } else {// 替换 jt.setText(comm); append = true; } } else if ("+-*/".indexOf(comm) != -1) { num1 = jt.getText(); operator = comm; append = false; } else if ("=".equals(comm)) { String num2 = jt.getText(); double d1 = Double.parseDouble(num1); double d2 = Double.parseDouble(num2); if ("+".equals(operator)) { d1 = d1 + d2; } else if ("-".equals(operator)) { d1 = d1 - d2; } else if ("*".equals(operator)) { d1 = d1 * d2; } else if ("/".equals(operator)) { d1 = d1 / d2; } jt.setText(d1 + ""); append = false; } else if (".".equals(comm)) {//追加小数点； String temp = jt.getText(); jt.setText(temp + "."); append = true; } else if ("+/-".equals(comm)) { String temp = jt.getText(); if (temp.startsWith("-")) { jt.setText(temp.substring(1)); } else { jt.setText("-" + temp); } } else if ("CE".equals(comm) || "C".equals(comm)) { jt.setText("0"); append = false; } else if ("BackS".equals(comm)) { String temp = jt.getText(); if (temp.length() > 0) { jt.setText(temp.substring(0, temp.length() - 1)); } } } public static void main(String[] args) { CalculatorDemo c = new CalculatorDemo(); c.makeCalculator(); }}
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