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

public class Example18_13 extends Applet implements KeyListener,ActionListener
{   Label label=new Label("點擊一個積木，然后移動它");
    Button b[ ]=new Button[40];
    int x[ ]=new int[40];
    int y[ ]=new int[40];
    String s[ ]=new String[40];

    public void init( )
    {   setLayout(null);
        add(label);
        label.setBounds(0,0,150,30);
        int k1=70,k2=70,k3=70,k4=70;
        for(int i=0;i<40;i++)
        {   b[i]=new Button(String.valueOf(i));
            if(i%3==0) b[i].setBackground(Color.red);
            if(i%3==1) b[i].setBackground(Color.blue);
            if(i%3==2) b[i].setBackground(Color.yellow);
            b[i].addKeyListener(this);    //按鈕獲得鍵盤事件監視器
            b[i].addActionListener(this);
            add(b[i]);
            if(i%4==0)           {   b[i].setBounds(k1,40,30,30);k1=k1+31;   }
            else if(i%4==1)   {   b[i].setBounds(k2,71,30,30);k2=k2+31;   }
            else if(i%4==2)   {   b[i].setBounds(k3,102,30,30);k3=k3+31;   }
            else if(i%4==3)   {   b[i].setBounds(k4,133,30,30);k4=k4+31;   }
        }
        for(int i=0;i<40;i++)
        {   x[i]=b[i].getBounds( ).x;
            y[i]=b[i].getBounds( ).y;    //獲得按鈕左上角的x,y 坐標
        }
    }

    public void keyTyped(KeyEvent e)
    {    }

    public void keyPressed(KeyEvent e)
    {   if(e.getKeyCode( )==KeyEvent.VK_UP)
        {   for(int i=0;i<=39;i++)
            {   if(s[i].equals(String.valueOf(i)))
                {   y[i]=y[i]-2;
                    if(y[i]<=0)  y[i]=0;
                    b[i].setLocation(x[i],y[i]);
                }
            }
        }
        else if(e.getKeyCode( )==KeyEvent.VK_DOWN)
        {   for(int i=0;i<=39;i++)
            {   if(s[i].equals(String.valueOf(i)))
                {   y[i]=y[i]+2;
                    if(y[i]>=300)  y[i]=300;
                    b[i].setLocation(x[i],y[i]);
                }
            }
        }
        else if(e.getKeyCode( )==KeyEvent.VK_LEFT)
        {   for(int i=0;i<=39;i++)
            {   if(s[i].equals(String.valueOf(i)))
                {   x[i]=x[i]-2;
                    if(x[i]<=0)  x[i]=0;
                    b[i].setLocation(x[i],y[i]);
                }
            }
        }
        else if(e.getKeyCode( )==KeyEvent.VK_RIGHT)
        {   for(int i=0;i<=39;i++)
            {   if(s[i].equals(String.valueOf(i)))
                {   x[i]=x[i]+2;
                    if(x[i]>=300)  x[i]=300;
                    b[i].setLocation(x[i],y[i]);
                }
            }
        }
    }

    public void keyReleased(KeyEvent e)
    {    }

    public void actionPerformed(ActionEvent e)
    {   for(int i=0;i<40;i++)
        {   if(e.getSource( )==b[i])
            {   for(int j=0;j<=39;j++)
                    s[j]=b[i].getLabel( );
            }
        }
    }
}