/* 
	This is a more advance calculator that
	
*	
*/


import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class AdvanceCalculator extends JFrame
{
	JTextArea textarea;
	double currentTotal = 0.0;
	char choice;
	JPanel mainpanel;
	JPanel buttonpanel;
	JButton clear;
	JButton zero;
	JButton one;
	JButton two;
	JButton three;
	JButton four;
	JButton five;
	JButton six;
	JButton seven;
	JButton eight;
	JButton nine;
	JButton decimal;
	JButton plus;
	JButton equal;
	JButton times;
	JButton divide;
	
	public AdvanceCalculator()
	{
			// Sets the window title
			
			setTitle("Advance Calculator");
			
			// Sets the size of the window
			
			setSize(300, 400);
			
			// Sets the start location of the window
			
			setLocationRelativeTo(null);
			
			// Sets the action when window is close
			
			setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

			//Sets the length of the text field
			
			textarea = new JTextArea("", 1,13);
			
			
			//Creates a panel using GridLayout
			buttonpanel = new JPanel();
			buttonpanel.setLayout(new java.awt.GridLayout(10,2)); 
		   mainpanel = new JPanel();
			mainpanel.setLayout(new BorderLayout());
			
			//create the buttons
		 	clear = new JButton("Clear");
		   zero = new JButton("0");
			one = new JButton("1");
			two = new JButton("2");
		   three = new JButton("3");
			four = new JButton("4");
			five = new JButton("5");
		   six = new JButton("6");
			seven = new JButton("7");
			eight = new JButton("8");
			nine = new JButton("9");
			decimal = new JButton(".");
			plus = new JButton("+");
			times = new JButton("X");
			divide = new JButton("/");
			equal = new JButton("=");
			
			//sets the actionlistener
			clear.addActionListener(new ButtonListener());
			one.addActionListener(new ButtonListener());
			two.addActionListener(new ButtonListener()); 
			three.addActionListener(new ButtonListener());
			four.addActionListener(new ButtonListener());
			five.addActionListener(new ButtonListener());
			six.addActionListener(new ButtonListener());
			seven.addActionListener(new ButtonListener());
			eight.addActionListener(new ButtonListener());
			nine.addActionListener(new ButtonListener());
			zero.addActionListener(new ButtonListener());
			plus.addActionListener(new ButtonListener());
			equal.addActionListener(new ButtonListener());
			decimal.addActionListener(new ButtonListener());
			times.addActionListener(new ButtonListener());
			divide.addActionListener(new ButtonListener());
			
			//adds the button to the panel
			
			buttonpanel.add(zero);
			buttonpanel.add(one);
			buttonpanel.add(two); 
			buttonpanel.add(three);
			buttonpanel.add(four);
			buttonpanel.add(five);
			buttonpanel.add(six);
			buttonpanel.add(seven);
			buttonpanel.add(eight);
			buttonpanel.add(nine);
			buttonpanel.add(times);
			buttonpanel.add(plus);
			buttonpanel.add(divide); 
			buttonpanel.add(decimal);
			buttonpanel.add(equal);
			buttonpanel.add(clear);
			
			// Adds the buttonpanel to the main panel
			
			mainpanel.add(buttonpanel, BorderLayout.CENTER);
			mainpanel.add(textarea, BorderLayout.NORTH);
			
			// Adds the mainpanel to the content pane
			
			add(mainpanel);
		
			// Sets the visibility of the window
			
			setVisible(true);
		
		}
		
		public class ButtonListener implements ActionListener
		{
			
			// This is the action it will perform when a button is pushed
			
			public void actionPerformed(ActionEvent e)
			{	
				// Append texts to text area if a number button is clicked
				
				try
				{
				   if(e.getSource( )== zero)
					{
						textarea.append("0");
						
					}
					if(e.getSource( )== one)
					{
						textarea.append("1");
						
					}
					if(e.getSource() == two)
					{
						textarea.append("2");
								
					}
					if(e.getSource() == three)
					{
						textarea.append("3");
						
					}
					if(e.getSource() == four)
					{
						textarea.append("4");
						
					}
					if(e.getSource() == five)
					{
						textarea.append("5");
						
					}
					if(e.getSource() == six)
					{
						textarea.append("6");
						
					}
					if(e.getSource() == seven)
					{
						textarea.append("7");
						
					}
					if(e.getSource() == eight)
					{
						textarea.append("8");
						
					}
					if(e.getSource() == nine)
					{
						textarea.append("9");
						
					}
					if(e.getSource() == decimal)
					{
						textarea.append(".");
					}
			
					// Addition is done in here
					
					if(e.getSource()== plus)
					{
						
						currentTotal += Double.parseDouble(textarea.getText());
						textarea.setText("");
						choice = '+';
					
					}
					
					// Mulitplication is done in here
					
					if(e.getSource()==times)
					{
						
						if( currentTotal == 0.0 )
						{
							currentTotal = 1;
							currentTotal *= Double.parseDouble(textarea.getText());
							textarea.setText("");
							choice = 'x';
						}
						else
						{
							currentTotal *= Double.parseDouble(textarea.getText());
							textarea.setText("");
							choice = 'x';
						}
					
					}
					
					if(e.getSource() == divide)
					{
						currentTotal = Double.parseDouble(textarea.getText());
						textarea.setText("");
						choice = '/';
						
					}
					
					// Outputs the result
					
					if(e.getSource() == equal)
					{
						if(choice == '+')
						{
							currentTotal += Double.parseDouble(textarea.getText());
							
						}
						if(choice == 'x')
						{
							currentTotal *= Double.parseDouble(textarea.getText());
							
						}
						if(choice =='/')
						{
							double num = Double.parseDouble(textarea.getText());
							
							if(num==0)
							{
								JOptionPane.showMessageDialog(null,"Error, dividing by zero");
								
							}
							else
							{
								currentTotal /= Double.parseDouble(textarea.getText());
								
							}
						}
						
						textarea.setText(""+currentTotal);
						
					}
			
					// Clears everything on the text area
					
					if(e.getSource() == clear)
					{

						textarea.setText("");
					 	currentTotal=0.0;
				
					}
				}
				catch(NumberFormatException ae)
				{
				}
				
		}
	}
	
	public static void main(String[] args)
	{
		 new AdvanceCalculator();
	}
}