本文实例讲述了java实现的计算器功能。分享给大家供大家参考，具体如下：
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.jb51.net - 计算器");
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("除数不能为零");
} else {
resultNum /= getNumberFromText();
}
} else if (operator.equals("1/x")) {
if (resultNum == 0.0) {
operateValidFlag = false;
resultText.setText("零没有倒数");
} 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);
}
}
运行效果：
PS：这里再为大家推荐几款计算工具供大家进一步参考借鉴：
在线一元函数（方程）求解计算工具：
http://tools.jb51.net/jisuanqi/equ_jisuanqi
科学计算器在线使用_高级计算器在线计算：
http://tools.jb51.net/jisuanqi/jsqkexue
在线计算器_标准计算器：
http://tools.jb51.net/jisuanqi/jsq
更多关于java算法相关内容感兴趣的读者可查看本站专题：《Java数据结构与算法教程》、《Java操作DOM节点技巧总结》、《Java文件与目录操作技巧汇总》和《Java缓存操作技巧汇总》
希望本文所述对大家java程序设计有所帮助。