calculator.java

自己写的一个计算器

package calculator;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Calculator extends JPanel implements ActionListener, KeyListener {
	
	private String command, arg, chg, txt;

	private double result;

	private String number = "123456789.0";

	private String operator = "/*-+=";

	private JTextField resultField;

	private JButton numbut[];

	private JButton combut[]; 

	private JPanel companel = new JPanel();
	
	private JPanel numpanel = new JPanel();

	public static void main(String[] arguments) {
		JFrame frame= new JFrame();
		frame.getContentPane().add(new Calculator(),BorderLayout.CENTER);
		frame.setSize(350, 250);
		frame.setVisible(true);
		frame.setResizable(false);
	}

	public Calculator() {
		addKeyListener(this);
		setBackground(Color.blue);
		companel.setBackground(Color.blue);
		numpanel.setBackground(Color.blue);
		
		this.setLayout(new GridLayout(1, 1));
		GridBagLayout gridbag = new GridBagLayout();
		GridBagConstraints constraints = new GridBagConstraints();
		setLayout(gridbag);
		constraints.weighty = 1;
		constraints.weightx = 1;
		Font bigFont = new Font("Courier", Font.BOLD, 14);
		resultField = new JTextField(20);
		constraints.gridwidth = GridBagConstraints.REMAINDER;
		gridbag.setConstraints(resultField, constraints);
		
		add(resultField);
		resultField.setFont(bigFont);
		resultField.setEditable(false);
		resultField.setForeground(Color.black);
		resultField.setBackground(Color.white);
		resultField.addKeyListener(this);
		resultField.requestFocus();
		resultField.setColumns(20);
		resultField.setSize(resultField.getPreferredSize());
		
		constraints.weighty = 1;
		constraints.weightx = 1;
		
		constraints.gridwidth = GridBagConstraints.REMAINDER;
		gridbag.setConstraints(companel, constraints);
		
		/* 
		 Command GridLayout 
		 --------------------- 
		 | Back |  CE  |  C | 
		 --------------------- 
		 */

		companel.setLayout(new GridLayout(1, 3, 5, 5));
		Font comsFont = new Font("Arial", Font.BOLD, 12);
		String[] coms = { "Back", "CE", "C" };
		combut = new JButton[3];
		for (int i = 0; i <= 2; i++) {
			combut[i] = new JButton(coms[i]);
			companel.add(combut[i]);
			combut[i].addActionListener(this);
			combut[i].setFont(comsFont);
			combut[i].addKeyListener(this);

		}
		add(companel);
		companel.addKeyListener(this);

		constraints.weighty = 4;
		constraints.weightx = 1;
		
		constraints.gridwidth = GridBagConstraints.REMAINDER;
		gridbag.setConstraints(numpanel, constraints);
		
		/* 
		 Number GridLayout 
		 --------------------- 
		 | 7 | 8 | 9 | / |sqr| 
		 --------------------- 
		 | 4 | 5 | 6 | * | % | 
		 --------------------- 
		 | 1 | 2 | 3 | - |1/x| 
		 --------------------- 
		 | 0 |+/-| . | + | = | 
		 --------------------- 
		 */
		numpanel.setLayout(new GridLayout(4, 5, 3, 3));
		// Create the buttons 
		String[] nums = { "7", "8", "9", "/", "sqrt", "4", "5", "6", "*", "%",
				"1", "2", "3", "-", "1/x", "0", "+/-", ".", "+", "=" };
		numbut = new JButton[20];
		for (int i = 0; i <= 19; i++) {
			numbut[i] = new JButton(nums[i]);
			numpanel.add(numbut[i]);
			numbut[i].addActionListener(this);
			numbut[i].addKeyListener(this);
			if (operator.indexOf(nums[i]) > -1) {
				numbut[i].setForeground(Color.red);
			} else {
				numbut[i].setForeground(Color.blue);
			}

		}
		
		add(numpanel);
		numpanel.addKeyListener(this);

		//initialize global variables. 
		command = "+";
		chg = "N";
		txt = "";
		arg = "";
		result = 0;
	}

	public void actionPerformed(ActionEvent e) {
	 if (e.getActionCommand() == "Back")
			back_space();
		else if (e.getActionCommand() == "CE")
			resultField.setText("");
		else if (e.getActionCommand() == "C") {
			result = 0;
			command = "+";
			resultField.setText("");
		} else {
			arg = e.getActionCommand();
			txt = resultField.getText();
			if (number.indexOf(arg) > -1) {
				if (chg == "Y")
					txt = "";
				txt = txt + arg;
				resultField.setText(txt);
				chg = "N";
			} else
				check_entry();
		}
	}

	public void keyPressed(KeyEvent k) {
	}

	public void keyReleased(KeyEvent k) {
		int ikey = k.getKeyCode();
		if (ikey == 127)
			resultField.setText("");
	}

	public void keyTyped(KeyEvent k) {
		int ikey = k.getKeyChar();
		if (ikey == 8)
			back_space();
		else if (ikey == 10) {
			arg = "=";
			txt = resultField.getText();
			display_ans();
		} else {
			txt = resultField.getText();
			char ckey = (char) ikey;
			arg = String.valueOf(ckey);
			if (number.indexOf(arg) > -1) {
				if (chg == "Y")
					txt = "";
				txt = txt + arg;
				resultField.setText(txt);
				chg = "N";
			} else
				check_entry();
		}
	}

	public void back_space() {
		txt = resultField.getText();
		int l = txt.length();
		if (l > 0) {
			txt = txt.substring(0, l - 1);
			resultField.setText(txt);
		}
	}

	public void display_ans() {
		resultField.setText(compute_tot(txt, command));
		chg = "Y";
		command = "+";
		result = 0;
	}

	public void check_entry() {
		if (arg.equals("="))
			display_ans();
		else if (arg.equals("%")) {
			resultField.setText(compute_tot(txt, arg));
			chg = "Y";
		} else if (operator.indexOf(arg) > -1) {
			if(txt==null ||txt.trim().equals(""))
				return;
			resultField.setText(compute_tot(txt, command));
			command = arg;
			chg = "Y";
		} else if (arg == "sqrt") {
			resultField.setText(compute_tot(txt, arg));
			chg = "Y";
			command = "";
		} else if (arg == "+/-") {
			Double tnum = Double.valueOf(txt);
			double num = tnum.doubleValue();
			num = num * -1;
			resultField.setText(String.valueOf(num));
			chg = "Y";
		} else if (arg == "1/x") {
			resultField.setText(compute_tot(txt, arg));
			chg = "Y";
		}
	}

	
	String compute_tot(String t, String c) {
	
		
		Double tnum = Double.valueOf(t);
		double num = tnum.doubleValue();

		if (c.equals("+"))
			result = result + num;
		else if (c.equals("-"))
			result = result - num;
		else if (c.equals("*"))
			result = result * num;
		else if (c.equals("/"))
			result = result / num;
		else if (c.equals("%"))
			result = num / 100;
		else if (c.equals("+/-"))
			result = num * -1;
		else if (c.equals("1/x"))
			result = 1.000 / num;
		else if (c.equals("sqrt"))
			result = Math.sqrt(num);
		return String.valueOf(result);
	}
}