本文實例講述了java實現的計算器功能。分享給大家供大家參考，具體如下：
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package awtDemo;import java.awt.BorderLayout;import java.awt.Color;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;@SuppressWarnings("serial")public class Calculator extends JFrame implements ActionListener { private final String[] KEYS = { "7", "8", "9", "/", "sqrt", "4", "5", "6", "*", "%", "1", "2", "3", "-", "1/x", "0", "+/-", ".", "+", "=" }; private final String[] COMMAND = { "Backspace", "CE", "C" }; private JButton keys[] = new JButton[KEYS.length]; private JButton commands[] = new JButton[COMMAND.length]; private JTextField resultText = new JTextField("0"); private boolean firstDigit = true; private double resultNum = 0.0; private String operator = "="; private boolean operateValidFlag = true; public Calculator() { init(); this.setBackground(Color.LIGHT_GRAY); this.setTitle("www.jfrwli.cn - 計算器"); this.setLocation(500, 300); this.setResizable(false); this.pack(); } private void init() { resultText.setHorizontalAlignment(JTextField.RIGHT); resultText.setEditable(false); resultText.setBackground(Color.white); JPanel calckeysPanel = new JPanel(); calckeysPanel.setLayout(new GridLayout(4, 5, 3, 3)); for (int i = 0; i < KEYS.length; i++) { keys[i] = new JButton(KEYS[i]); calckeysPanel.add(keys[i]); keys[i].setForeground(Color.blue); } keys[3].setForeground(Color.red); keys[8].setForeground(Color.red); keys[13].setForeground(Color.red); keys[18].setForeground(Color.red); keys[19].setForeground(Color.red); JPanel commandsPanel = new JPanel(); commandsPanel.setLayout(new GridLayout(1, 3, 3, 3)); for (int i = 0; i < COMMAND.length; i++) { commands[i] = new JButton(COMMAND[i]); commandsPanel.add(commands[i]); commands[i].setForeground(Color.red); } JPanel panel1 = new JPanel(); panel1.setLayout(new BorderLayout(3, 3)); panel1.add("North", commandsPanel); panel1.add("West", calckeysPanel); JPanel top = new JPanel(); top.setLayout(new BorderLayout()); top.add("Center", resultText); getContentPane().setLayout(new BorderLayout(3, 5)); getContentPane().add("North", top); getContentPane().add("Center", panel1); for (int i = 0; i < KEYS.length; i++) { keys[i].addActionListener(this); } for (int i = 0; i < COMMAND.length; i++) { commands[i].addActionListener(this); } } public void actionPerformed(ActionEvent e) { String label = e.getActionCommand(); if (label.equals(COMMAND[0])) { handleBackspace(); } else if (label.equals(COMMAND[1])) { resultText.setText("0"); } else if (label.equals(COMMAND[2])) { handleC(); } else if ("0123456789.".indexOf(label) >= 0) { handleNumber(label); } else { handleOperator(label); } } private void handleBackspace() { String text = resultText.getText(); int i = text.length(); if (i > 0) { text = text.substring(0, i - 1); if (text.length() == 0) { resultText.setText("0"); firstDigit = true; operator = "="; } else { resultText.setText(text); } } } private void handleNumber(String key) { if (firstDigit) { resultText.setText(key); } else if ((key.equals(".")) && (resultText.getText().indexOf(".") < 0)) { resultText.setText(resultText.getText() + "."); } else if (!key.equals(".")) { resultText.setText(resultText.getText() + key); } firstDigit = false; } private void handleC() { resultText.setText("0"); firstDigit = true; operator = "="; } private void handleOperator(String key) { if (operator.equals("/")) { if (getNumberFromText() == 0.0) { operateValidFlag = false; resultText.setText("除數不能為零"); } else { resultNum /= getNumberFromText(); } } else if (operator.equals("1/x")) { if (resultNum == 0.0) { operateValidFlag = false; resultText.setText("零沒有倒數"); } else { resultNum = 1 / resultNum; } } else if (operator.equals("+")) { resultNum += getNumberFromText(); } else if (operator.equals("-")) { resultNum -= getNumberFromText(); } else if (operator.equals("*")) { resultNum *= getNumberFromText(); } else if (operator.equals("sqrt")) { resultNum = Math.sqrt(resultNum); } else if (operator.equals("%")) { resultNum = resultNum / 100; } else if (operator.equals("+/-")) { resultNum = resultNum * (-1); } else if (operator.equals("=")) { resultNum = getNumberFromText(); } if (operateValidFlag) { long t1; double t2; t1 = (long) resultNum; t2 = resultNum - t1; if (t2 == 0) { resultText.setText(String.valueOf(t1)); } else { resultText.setText(String.valueOf(resultNum)); } } operator = key; firstDigit = true; operateValidFlag = true; } private double getNumberFromText() { double result = 0; try { result = Double.valueOf(resultText.getText()).doubleValue(); } catch (NumberFormatException e) { } return result; } public static void main(String args[]) { Calculator calculator1 = new Calculator(); calculator1.setVisible(true); calculator1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); }} |
運行效果：
希望本文所述對大家java程序設計有所幫助。
原文鏈接：http://blog.csdn.net/wenzhilanyu2012/article/details/8721227
