import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.util.LinkedList;
import java.text.NumberFormat;

public class ComputerPad extends Frame implements ActionListener
{
	NumberButton numberButton[];
	OperationButton operationButton[];
	Button 小數點按鈕,正負號按鈕,退格按鈕,求倒數按鈕,等號按鈕,清零按鈕;
	Panel panel;
	JTextField resultShow;
	String 運算符號[]={"+","-","*","/"};
	LinkedList 鏈表;
	boolean 是否按下等號 =false;
	
	public ComputerPad()
	{
		super("計算器");
		鏈表 =new LinkedList();
		numberButton=new NumberButton[10];
		for(int i=0;i<=9;i++)
		{
			numberButton[i]=new NumberButton(i);
			numberButton[i].addActionListener(this);
		}
		operationButton=new OperationButton[4];
		for(int i=0;i<4;i++)
		{
			operationButton[i]=new OperationButton(運算符號[i]);
			operationButton[i].addActionListener(this);
		}
		小數點按鈕 =new Button(".");
		正負號按鈕 =new Button("+/-");
		等號按鈕 =new Button("=");
		求倒數按鈕 =new Button("1/x");
		退格按鈕 =new Button("退格");
		清零按鈕 =new Button("C");
		清零按鈕.setForeground(Color.red);
		退格按鈕.setForeground(Color.red);
		等號按鈕.setForeground(Color.red);
		求倒數按鈕.setForeground(Color.blue);
		正負號按鈕.setForeground(Color.blue);
		小數點按鈕.setForeground(Color.blue);
		退格按鈕.addActionListener(this);
		清零按鈕.addActionListener(this);
		等號按鈕.addActionListener(this);
		小數點按鈕.addActionListener(this);
		正負號按鈕.addActionListener(this);
		求倒數按鈕.addActionListener(this);
		resultShow=new JTextField(10);
		resultShow.setHorizontalAlignment(JTextField.RIGHT);
		resultShow.setForeground(Color.blue);
		resultShow.setFont(new Font("TimesRoman",Font.PLAIN,14));
		resultShow.setBorder(new SoftBevelBorder(BevelBorder.LOWERED));
		resultShow.setBackground(Color.white);
		resultShow.setEditable(false);
		panel=new Panel();
		panel.setLayout(new GridLayout(4,5));
		
		panel.add(numberButton[1]);
		panel.add(numberButton[2]);
		panel.add(numberButton[3]);
		panel.add(operationButton[0]);
		panel.add(清零按鈕);
		
		panel.add(numberButton[4]);
		panel.add(numberButton[5]);
		panel.add(numberButton[6]);
		panel.add(operationButton[1]);
		panel.add(退格按鈕);
		
		panel.add(numberButton[7]);
		panel.add(numberButton[8]);
		panel.add(numberButton[9]);
		panel.add(operationButton[2]);
		panel.add(求倒數按鈕);
		
		panel.add(numberButton[0]);
		panel.add(正負號按鈕);
		panel.add(小數點按鈕);
		panel.add(operationButton[3]);
		panel.add(等號按鈕);
		add(panel,BorderLayout.CENTER);
		add(resultShow,BorderLayout.NORTH);
		
		addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				System.exit(0);
			}
		});
		setVisible(true);
		setBounds(100,50,240,180);
		setResizable(false);
		validate();
	}
	
	public void actionPerformed(ActionEvent e)
	{
		if(e.getSource() instanceof NumberButton)
		{
			NumberButton b=(NumberButton)e.getSource();
			if(鏈表.size()==0)
			{
				int numb=b.getNumber();
				鏈表.add(" "+numb);
				resultShow.setText(" "+numb);
				是否按下等號 =false;
			}
			else if(鏈表.size()==1&&是否按下等號 ==false)
			{
				int numb=b.getNumber();
				String num=(String)鏈表.getFirst();
				String s=num.concat(" "+numb);
				鏈表.set(0,s);
				resultShow.setText(s);
			}
			else if(鏈表.size()==1&&是否按下等號 ==true)
			{
				int numb=b.getNumber();
				鏈表.removeFirst();
				鏈表.add(" "+numb);
				是否按下等號 =false;
				resultShow.setText(" "+numb);
			}
			else if(鏈表.size()==2)
			{
				int numb=b.getNumber();
				鏈表.add(" "+numb);
				
				resultShow.setText(" "+numb);
			}
			else if(鏈表.size()==3)
			{
				int numb=b.getNumber();
				String num=(String)鏈表.getLast();
				String s=num.concat(" "+numb);
				鏈表.set(2,s);
				resultShow.setText(s);
			}
		}
		else if(e.getSource() instanceof OperationButton)
		{
			OperationButton b=(OperationButton)e.getSource();
			if(鏈表.size()==1)
			{
				String fuhao=b.getOperator();
				
				鏈表.add(fuhao);
			}
			else if(鏈表.size()==2)
			{
				String fuhao=b.getOperator();
				鏈表.set(1,fuhao);
			}
			else if(鏈表.size()==3)
			{
				String fuhao=b.getOperator();
				String number1=(String)鏈表.getFirst();
				String number2=(String)鏈表.getLast();
				String 運算符號 =(String)鏈表.get(1);
				try
				{
					double n1=Double.parseDouble(number1);
					double n2=Double.parseDouble(number2);
					double n=0;
					if(運算符號.equals("+"))
					{
						n=n1+n2;
					}
					else if(運算符號.equals("-"))
					{
						n=n1-n2;
					}
					else if(運算符號.equals("*"))
					{
						n=n1*n2;
					}
					鏈表.clear();
					鏈表.add(" "+n);
					鏈表.add(fuhao);
					resultShow.setText(" "+n);
				}
				catch(Exception ee)
				{
				}
			}
		}
		else if(e.getSource()==等號按鈕)
		{
			是否按下等號 =true;
			if(鏈表.size()==1||鏈表.size()==2)
			{
				String num=(String)鏈表.getFirst();
				resultShow.setText(" "+num);
			}
			else if(鏈表.size()==3)
			{
				String number1=(String)鏈表.getFirst();
				String number2=(String)鏈表.getLast();
				String 運算符號 =(String)鏈表.get(1);
				try
				{
					double n1=Double.parseDouble(number1);
					double n2=Double.parseDouble(number2);
					double n=0;
					if(運算符號.equals("+"))		n=n1+n2;
					else if(運算符號.equals("-")) n=n1-n2;
					else if(運算符號.equals("*")) n=n1*n2;
					else if(運算符號.equals("/")) n=n1/n2;
					resultShow.setText(" "+n);
					鏈表.set(0," "+n);
					鏈表.removeLast();
					鏈表.removeLast();
				}
				catch(Exception ee){}
			}
		}
		else if(e.getSource()==小數點按鈕)
		{
			if(鏈表.size()==0)
			{
				是否按下等號 =false;
			}
			else if(鏈表.size()==1)
			{
				String dot=小數點按鈕.getLabel();
				String num=(String)鏈表.getFirst();
				String s=null;
				if(num.indexOf(dot)==-1)
				{
					s=num.concat(dot);
					鏈表.set(0,s);
				}
				else
				{
					s=num;
				}
				鏈表.set(0,s);
				resultShow.setText(s);
			}
			
			else if(鏈表.size()==3)
			{
				String dot=小數點按鈕.getLabel();
				String num=(String)鏈表.getLast();
				String s=null;
				if(num.indexOf(dot)==-1)
				{
					s=num.concat(dot);
					鏈表.set(2,s);
				}
				else
				{
					s=num;
				}
				resultShow.setText(s);
			}
		}
		else if(e.getSource()==退格按鈕)
		{
			if(鏈表.size()==1)
			{
				String num=(String)鏈表.getFirst();
				if(num.length()>=1)
				{
					num=num.substring(0,num.length()-1);
					鏈表.set(0,num);
					resultShow.setText(num);
				}
				else
				{
					鏈表.removeLast();
					resultShow.setText("0");
				}
			}
			else if(鏈表.size()==3)
			{
				String num=(String)鏈表.getLast();
				if(num.length()>=1)
				{
					num=num.substring(0,num.length()-1);
					鏈表.set(2,num);
					resultShow.setText(num);
				}
				else
				{
					鏈表.removeLast();
					resultShow.setText(" 0");
				}
			}
		}
		else if(e.getSource()==正負號按鈕)
		{
			if(鏈表.size()==1)
			{
				String number1=(String)鏈表.getFirst();
				try
				{
					double d=Double.parseDouble(number1);
					d=-1*d;
					String str=String.valueOf(d);
					鏈表.set(0,str);
					resultShow.setText(str);
				}
				catch(Exception ee)
				{}
			}
			else if(鏈表.size()==3)
			{
				String number2=(String)鏈表.getLast();
				try
				{
					double d=Double.parseDouble(number2);
					d=-1*d;
					String str=String.valueOf(d);
					鏈表.set(2,str);
					resultShow.setText(str);
				}
				catch(Exception ee){}
			}
		}
		else if(e.getSource()==求倒數按鈕)
		{
			if(鏈表.size()==1||鏈表.size()==2)
			{
				String number1=(String)鏈表.getFirst();
				try
				{
					double d=Double.parseDouble(number1);
					d=1.0/d;
					String str=String.valueOf(d);
					鏈表.set(0,str);
					resultShow.setText(str);
				}
				catch(Exception ee){}
			}
			else if(鏈表.size()==3)
			{
				String number2=(String)鏈表.getLast();
				try
				{
					double d=Double.parseDouble(number2);
					d=1.0/d;
					String str=String.valueOf(d);
					鏈表.set(0,str);
					resultShow.setText(str);
				}
				catch(Exception ee){}
			}
		}
		else if(e.getSource()==清零按鈕)
		{
			是否按下等號 =false;
			resultShow.setText(" 0");
			鏈表.clear();
		}
	}
	public static void main(String args[])
	{
		new ComputerPad();
	}
}