import javax.imageio.*;
import java.awt.image.*;
import java.security.NoSuchAlgorithmException;
import java.security.MessageDigest;
import java.lang.reflect.*;
import java.net.*;
import java.io.*;
import javax.swing.*;
import java.util.regex.*;
import java.util.zip.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.util.List;


public class main {
  static JTextArea textArea;
  static JTextField tfCmd;
  static List<String> history = new ArrayList<String>();
  static int historyIdx;
  
  public static void main(String[] args) throws Exception {
    JFrame frame = new JFrame("A JavaX Frame");
    
    JPanel panel = new JPanel(new BorderLayout());
    
    textArea = new JTextArea();
    panel.add(BorderLayout.CENTER, new JScrollPane(textArea));
    
    tfCmd = new JTextField();
    panel.add(BorderLayout.SOUTH, tfCmd);
    
    tfCmd.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent _evt) {

      tfCmd.selectAll();
      String cmd = tfCmd.getText();
      runCmd(cmd);
    
}});
    
    frame.addWindowListener(new WindowAdapter() {
      public void windowOpened(WindowEvent e) {
        tfCmd.requestFocus();
      }
    }); 
    
    frame.add(panel);
    frame.setBounds(100, 100, 500, 400);
    frame.setVisible(true);
    exitOnFrameClose(frame);
  }
  
  static void setText(String text) {
    if (text.equals(textArea.getText())) return;
    history.add(historyIdx++, textArea.getText());
    textArea.setText(text);
  }
  
  static void runCmd(String cmd) {
    if ("random chars".equals(cmd)) {
      String text = randomLetters(40);
      setText(text);
    } else if ("back".equals(cmd)) {
      if (historyIdx > 0)
        textArea.setText(history.get(--historyIdx));
    } else if ("hello".equals(cmd)) {
      setText("hello!");
    } else if ("java class".equals(cmd)) {
      setText("%636\n%modern\n\nmain {\n  static O androidContext;\n  static S programID;\n  \n  public static void main(String[] args) throws Exception {\n  }\n}\n".replace("%", "!"));
    }
  }

static String randomLetters(int n) {
  return makeRandomID(n);
}

  static void exitOnFrameClose(JFrame frame) {
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }


static String makeRandomID(int length) {
  Random random = new Random();
  char[] id = new char[length];
  for (int i = 0; i< id.length; i++)
    id[i] = (char) ((int) 'a' + random.nextInt(26));
  return new String(id);
}
}