calculator.java

简单的计算器程序 java版 使用JFrame

//如果你想加sin cos tan的话就建它们的按钮
//在actionPerformed方法中的if-else语句中加else if (btn == sin){operate('S');operate('=');equaled = true;}
//然后在operate方法加对应的语句就行了.记忆M+, M-没时间搞 这个应该比较简单容易明白吧.
import javax.swing.*;

import java.awt.*;
import java.awt.event.*;

public class Calculator extends JFrame implements ActionListener {
	private boolean dotExist, operated, equaled; // 帮助运算的布尔变量

	private double storedNumber; // 目前的结果

	private char lastOperator; // 表示上一运算符

	private JTextField operation; // 结果栏

	private JButton dot, plus, minus, multi, div, sqrt, equal, changePN, clear; // 运算符

	private JButton[] numbers; // 数字
	// 构造者

	public Calculator() {
		setTitle("Calculator");
//		JPanel panel=new JPanel();
		// 初始化变量
		dotExist = false; // 表示当前的数是否有小数点
		operated = false; // 表示任意运算符是否被按下
		equaled = false; // 表示等号是否被按下
		storedNumber = 0;
		lastOperator = '?';
		// 初始化窗口变量
		operation = new JTextField("0");
		operation.setEditable(false);
		numbers = new JButton[10];
		for (int i = 0; i < 10; i++)
			numbers[i] = new JButton("" + i);
		dot = new JButton(".");
		plus = new JButton("+");
		minus = new JButton("-");
		multi = new JButton("*");
		div = new JButton("/");
		sqrt = new JButton("√");
		equal = new JButton("=");
		changePN = new JButton("±");
		clear = new JButton("AC");
		// 将窗口物体放入窗口
		GridBagLayout layout = new GridBagLayout();
//		this.getContentPane().add(panel,"Center");
		getContentPane().setLayout(layout);
		addComponent(layout, operation, 0, 0, 4, 1);
		addComponent(layout, numbers[1], 1, 0, 1, 1);
		addComponent(layout, numbers[2], 1, 1, 1, 1);
		addComponent(layout, numbers[3], 1, 2, 1, 1);
		addComponent(layout, numbers[4], 2, 0, 1, 1);
		addComponent(layout, numbers[5], 2, 1, 1, 1);
		addComponent(layout, numbers[6], 2, 2, 1, 1);
		addComponent(layout, numbers[7], 3, 0, 1, 1);
		addComponent(layout, numbers[8], 3, 1, 1, 1);
		addComponent(layout, numbers[9], 3, 2, 1, 1);
		addComponent(layout, dot, 4, 0, 1, 1);
		addComponent(layout, numbers[0], 4, 1, 1, 1);
		addComponent(layout, sqrt, 4, 2, 1, 1);
		addComponent(layout, plus, 1, 3, 1, 1);
		addComponent(layout, minus, 2, 3, 1, 1);
		addComponent(layout, multi, 3, 3, 1, 1);
		addComponent(layout, div, 4, 3, 1, 1);
		addComponent(layout, equal, 5, 0, 2, 1);
		addComponent(layout, changePN, 5, 2, 1, 1);
		addComponent(layout, clear, 5, 3, 1, 1);
//		RepaintManager.currentManager(getRootPane()).setDoubleBufferingEnabled(false);
//		panel.setDebugGraphicsOptions(DebugGraphics.FLASH_OPTION);
	}

	// 对按钮进行反应的方法
	public void actionPerformed(ActionEvent e) {
		JButton btn = (JButton) e.getSource();
		if (btn == clear) {
			operation.setText("0");
			dotExist = false;
			storedNumber = 0;
			lastOperator = '?';
		} else if (btn == equal) {
			operate('=');
			equaled = true;
		} else if (btn == plus) {
			operate('+');
			equaled = false;
		} else if (btn == minus) {
			operate('-');
			equaled = false;
		} else if (btn == multi) {
			operate('*');
			equaled = false;
		} else if (btn == div) {
			operate('/');
			equaled = false;
		} else if (btn == changePN) {
			operate('p');
			operate('=');
			equaled = true;
		} else if (btn == sqrt) {
			operate('s');
			operate('=');
			equaled = true;
		} else {
			if (equaled)
				storedNumber = 0;
			for (int i = 0; i < 10; i++)
				if (btn == numbers[i]) {
					if (operation.getText().equals("0"))
						operation.setText("" + i);
					else if (!operated)
						operation.setText(operation.getText() + i);
					else {
						operation.setText("" + i);
						operated = false;
					}
				}
			if (btn == dot && !dotExist) {
				operation.setText(operation.getText() + ".");
				dotExist = true;
			}
		}
	}

	// 进行运算的方法
	private void operate(char operator) {
		double currentNumber = Double.valueOf(operation.getText())
				.doubleValue();
		if (lastOperator == '?')
			storedNumber = currentNumber;
		else if (lastOperator == '+')
			storedNumber += currentNumber;
		else if (lastOperator == '-')
			storedNumber -= currentNumber;
		else if (lastOperator == '*')
			storedNumber *= currentNumber;
		else if (lastOperator == '/')
			storedNumber /= currentNumber;
		else if (lastOperator == 'p')
			storedNumber *= -1;
		else if (lastOperator == 's')
			storedNumber = Math.sqrt(currentNumber);
		else if (lastOperator == '=' && equaled)
			storedNumber = currentNumber;
		operation.setText("" + storedNumber);
		operated = true;
		lastOperator = operator;
	}

	// 快捷使用GridBagLayout的方法
	private void addComponent(GridBagLayout layout, Component component,
			int row, int col, int width, int height) {
		GridBagConstraints constraints = new GridBagConstraints();
		constraints.fill = GridBagConstraints.BOTH;
		constraints.insets = new Insets(10, 2, 10, 2);
		constraints.weightx = 100;
		constraints.weighty = 100;
		constraints.gridx = col;
		constraints.gridy = row;
		constraints.gridwidth = width;
		constraints.gridheight = height;
		layout.setConstraints(component, constraints);
		if (component instanceof JButton)
			((JButton) component).addActionListener(this);
		getContentPane().add(component);
	}

	// 主方法初始化并显示窗口
	public static void main(String[] args) {
		Calculator calc = new Calculator();
		calc.setSize(290, 400);

		calc.setVisible(true);
	}
}