// Written by:	Darren Gates & Ray Klefstad
// Date:	January 2000
// School:	U.C. Irvine

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class CharacterStringsExample
    extends Applet
{
    private TextField testField;
    
    public void init()
    {
        setLayout(new GridLayout(3, 1));
        
        // a panel containing only the test field
        Panel testPanel = new Panel();
        testField = new TextField("Hello World!", 20);
        testPanel.add(testField);
        
        CharAt CharAtTest = new CharAt("CharAt");
        Concat ConcatTest = new Concat("Concat");
        
        add(testPanel);
        add(CharAtTest);
        add(ConcatTest);
    }
    
    class CharAt
        extends Panel
        implements ActionListener
    {
        private Button myButton;
        private TextField myTextField;
        private TextField result;
        
        public CharAt(String name)
        {
            myButton = new Button(name);
            myTextField = new TextField(5);
            result = new TextField(10);
            
            add(myButton);  
            add(myTextField);
            add(result);
            
            myButton.addActionListener(this);
        }
        
        public void actionPerformed(ActionEvent e)
        {
            try
            {
                int indexNum = Integer.parseInt(myTextField.getText());
                result.setText("" + testField.getText().charAt(indexNum));
            }
            catch(NumberFormatException error)
            {
                result.setText("Bad Format");
            }
            catch(IndexOutOfBoundsException error)
            {
                result.setText("Out of Range");
            }
        }            
    }
        
    class Concat
        extends Panel
        implements ActionListener
    {
        private Button myButton;
        private TextField myTextField;
        private TextField result;
        
        public Concat(String name)
        {
            myButton = new Button(name);
            myTextField = new TextField(10);
            result = new TextField(20);
            
            add(myButton);  
            add(myTextField);
            add(result);
            
            myButton.addActionListener(this);
        }
        
        public void actionPerformed(ActionEvent e)
        {
            result.setText(testField.getText() + myTextField.getText());
        }            
    }
}