import java.awt.*;			
import javax.swing.*;
import java.awt.event.*;
import java.util.*;			// for LinkedList

public class Ch22_2			// implement a GUI that inputs integer numbers and stores them in a LinkedList<Integer>
{							// JButtons allow us to manipulate the LinkedList, with the output displayed in a JTextArea
	public static void main(String[] args)
	{
		JFrame f=new JFrame();		// set up our GUI
		f.setSize(300,200);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		NumberPanel np=new NumberPanel();
		f.add(np);
		f.setVisible(true);
	}
	
	// JPanel inner class which will store our LinkedList (list), have 3 JButtons and a JTextField for input and a JTextArea
	public static class NumberPanel extends JPanel implements ActionListener		// for output
	{
		private LinkedList<Integer> list;		// our list of Integer values
		private JTextArea jta;					// for output
		private JTextField input;				// for input
					// note:  JButtons could be declared here if desired
		public NumberPanel()		// set up the GUI
		{
			JLabel lab=new JLabel("Enter a number:");	// JLabel to describe what to input
			input=new JTextField("",10);				// create our JTextField, have it implement ActionListener
			input.addActionListener(this);				// to respond when something is typed in followed by <enter>
			jta=new JTextArea(3,20);				// our output area, 3 rows, 20 columns
			jta.setLineWrap(true);					// using word wrap
			jta.setWrapStyleWord(true);
			JButton sort=new JButton("Sort");			// our JButtons which will also implement ActionListener
			JButton shuffle=new JButton("Shuffle");
			JButton reverse=new JButton("Reverse");
			sort.addActionListener(this);
			shuffle.addActionListener(this);
			reverse.addActionListener(this);
			JPanel p1=new JPanel();					// now position them nicely
			p1.add(lab);
			p1.add(input);
			JPanel p2=new JPanel();
			p2.add(sort);
			p2.add(shuffle);
			p2.add(reverse);
			JPanel p3=new JPanel(new BorderLayout());
			p3.add(p1,BorderLayout.NORTH);
			p3.add(jta,BorderLayout.CENTER);
			p3.add(p2,BorderLayout.SOUTH);
			add(p3);
			list=new LinkedList<>();				// create our LinkedList, initially empty
		}
		
		private void display()			// helper method, only called from actionPerformed
		{
			String temp="";				// we will build a new String to output in jta
			for(Integer temp2:list)			// add each Integer in list to it, one at a time
				temp+=""+temp2+" ";
			jta.setText(temp);				// display this String in jta
		}
		
		public void actionPerformed(ActionEvent e)		// invoked if user enters something in input or clicks a JButton
		{
			if(e.getSource()==input)			// if input, grab the String, make it an Integer, add it to LinkedList
			{
				Integer temp=new Integer(Integer.parseInt(input.getText()));
				input.setText("");				// reset the input box to empty
				list.add(temp);
				display();						// call display to display the new version of our list
			}
			else if(e.getActionCommand().equals("Sort"))	// upon sort, use Collections class to sort list and display it
			{
				Collections.sort(list);
				display();		
			}
			else if(e.getActionCommand().equals("Shuffle"))  // upon shuffle, use Collections class to shuffle list and display it
			{
				Collections.shuffle(list);
				display();						
			}
			else if(e.getActionCommand().equals("Reverse"))  // upon reverse, use Collections class to reverse list and display it
			{
				Collections.reverse(list);
				display();
			}
		}
	}
}