Исходный текст программы MoveBox.java

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// ==========================================
// MoveBox.java
//(C) Alexandr Frolov, 1998
// E-mail: frolov@glasnet.ru
// Web:    http://www.glasnet.ru/~frolov 
// ==========================================

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

public class MoveBox extends Applet
{
  int nxCurrent;
  int nyCurrent;
  Dimension dm;
  final static int nBlockSize = 10;

  // ============================================
  // getAppletInfo
  // ============================================
  public String getAppletInfo()
  {
    return "Name: MoveBox";
  }

  // ============================================
  // init
  // ============================================
  public void init()
  {
    dm = size();
    nxCurrent = (dm.width / 2) - nBlockSize;
    nyCurrent = (dm.height / 2) - nBlockSize;
    
    setBackground(Color.yellow);
    setForeground(Color.black);
  }

  // ============================================
  // paint
  // ============================================
  public void paint(Graphics g)
  {
    g.setColor(Color.red);
    g.setFont(new Font(
      "Helvetica", Font.BOLD, 24));
    g.drawString("Move it whith keyboard!",
      10, 30);
    
    DrawIt(g);
  }

  // ============================================
  // DrawIt
  // ============================================
  void DrawIt(Graphics g)
  {
    g.setColor(Color.black);
    g.fillRect(nxCurrent, nyCurrent, 
      2 * nBlockSize, 2 * nBlockSize);
  }
  
  // ============================================
  // keyDown
  // ============================================
  public boolean keyDown(Event evt, int key) 
  {
    switch(key)
    {
      case Event.LEFT:
      {
	if(nxCurrent > 0)
	  nxCurrent -= nBlockSize;
	else 
          nxCurrent = 
            dm.width - nBlockSize * 2;
	break;
      }
      
      case Event.RIGHT:
      {
	if(nxCurrent < dm.width - nBlockSize)
	  nxCurrent += nBlockSize;
	else 
          nxCurrent = 0;
	break;
      }
      
      case Event.DOWN:
      {
	if(nyCurrent < dm.height - nBlockSize)
	  nyCurrent += nBlockSize;
	else 
          nyCurrent = 0;
	break;
      }
      
      case Event.UP:
      {
	if(nyCurrent > 0)
	  nyCurrent -= nBlockSize;
	else 
          nyCurrent = 
            dm.height - nBlockSize * 2;
	break;
      }
    }
    repaint();

    return true;
  }

  // ============================================
  // keyUp
  // ============================================
  public boolean keyUp(Event evt, int nKey) 
  {
    return true;
  }
}

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