// File: GUI_Example.java

// Demonstrates methods showInputDialog, and showMessageDialog of the 
// JOPtionPane class.  These methods enable input and output of
// strings, using simple Graphical User Interfaces (GUI's).
//
// Also shows how to create a scrollable window for output:
//   1. Create a JTextArea object with a specified number of rows
//      and columns
//   2. Use method setText to assign a string to the JTextArea obj
//   3. To get scroll bars around the JTextArea obj, create a 
//      JScrollPane obj with the JTextArea obj as a parameter.
//   4. Display window and contents using showMessageDialog method
//   NOTE: As shown below, this is "easier DONE than SAID!"  :-)

import javax.swing.* ;		// for classes JOPtionPane & JTextArea

public class GUI_Example 
{
	// Basic input and output
	public static void main(String[] args) 
	{
		// show input box and assign value entered to String obj "input"
		String input = JOptionPane.showInputDialog("Enter a number") ;
		
		int aNumber = Integer.parseInt(input);	// make it an int
		
		// display the input number in an output box
		JOptionPane.showMessageDialog(null, "The input is " + aNumber) ;
		
		// overloaded showInputDialog method - the 3rd parameter displays
		// in the title bar and the fourth displays "?" icon
		input = JOptionPane.showInputDialog(null,"Enter a number",
		                                    "\u00BFQue numero?",
		                                     JOptionPane.QUESTION_MESSAGE) ;
		
		aNumber = Integer.parseInt(input) ;
		
		// fourth parameter means "no icon"
		JOptionPane.showMessageDialog(null, "The input is " + aNumber,
		                              "Back atcha!", 
		                              JOptionPane.PLAIN_MESSAGE) ;
		
		// A JTextArea is a rectangular output area of rows and columns
		int rows = 25 ;
		int columns = 40 ;
		JTextArea outArea = new JTextArea(rows,columns) ;
		
		// create humongous, multi-line o/p string
		String output = "" ;			
		for(int i = 0 ; i < 100 ; i++ ) 
		{
			String blanks = "  " ;
			for( int j = 0 ; j < i ; j++) 
			{
				blanks += "  " ;
			}
			output += blanks + i + "\n" ;
		}
		
		// Assign the output string to the output area
		outArea.setText(output) ;
		
		// The JScrollPane puts scroll bars around the output area
		JOptionPane.showMessageDialog(null,new JScrollPane(outArea)) ;
		
		// The same area using a title and no icon
		JOptionPane.showMessageDialog(null,new JScrollPane(outArea),
		                              "Output Area", JOptionPane.PLAIN_MESSAGE);
		                              
		// next statement required when GUI's are used
		System.exit(0) ;
	}
}