How to settle an an image in Applet for tetris game

问题

I developing tetris game using applets. I have generated random shapes and making it move. But i don't know how to make it settle at the bottom. My shapes are vanishing once it reaches the end of the screen. Please help me on this regard. Here goes my code.

import java.applet.Applet;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JFrame;
import javax.swing.JLabel;



public class TetrisGame
{
    public static void main (String argsp[])
    {
        JFrame frame = new JFrame("Tetris");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final AppletClass applet = new AppletClass();
        frame.getContentPane().add(applet);
        applet.init();
        Thread t = new Thread(new Runnable()
        {

            @Override
            public void run() 
            {
                while(true)
                {
                    try 
                    {
                        Thread.sleep(1000);
                        applet.repaint();
                    }
                    catch (InterruptedException e) 
                    {
                        e.printStackTrace();
                    }               
                }
            }

        });
        t.start();

        frame.setBounds(10,10,410,610);
        frame.setVisible(true);
    }
}

class AppletClass extends Applet implements KeyListener
{

    private static final long serialVersionUID = 1L;
    static int xpos = 190;
    static int ypos =0;
    static int random1;
    static int reached_end=1;


    public void init()
    {
             System.out.println("aaa");
        setFocusable(true);
        requestFocus();
        addKeyListener(this);

    }
    public void paint (Graphics g)
    {

        generateRandomShapes(g);
    }

    public void generateRandomShapes (Graphics g)
    {

        int i=0;
        int x[] = new int[4];
        int y[] = new int[4];

        if(reached_end==1)
        {
            random1=(int)Math.floor(Math.random()*100);
            ypos=0;
        }

        x[0]=xpos;
        ypos =ypos+30;
        y[0]=ypos;

        if(ypos>420)
        {
            reached_end=1;
            ypos=0;
        }
        else
            reached_end=0;





        switch(random1%7)
        {
                case 0:
                    //straight line
                    for(i = 0;i<3;i++)
                    {
                        x[i+1]=x[i];
                        y[i+1]=y[i]+30;
                    }
                    break;
                case 1:
                    //L shape
                    for(i = 0;i<2;i++)
                    {
                        x[i+1]=x[i];
                        y[i+1]=y[i]+30;
                    }
                    x[i+1]=x[i]+30;
                    y[i+1]=y[i];
                    break;
                case 2:
                    //reverse L shape
                    for(i = 0;i<2;i++)
                    {
                        x[i+1]=x[i];
                        y[i+1]=y[i]+30;
                    }
                    x[i+1]=x[i]-30;
                    y[i+1]=y[i];
                    break;
                case 3:
                    //square shape
                    i=0;
                        x[i+1]=x[i];
                        y[i+1]=y[i]+30;
                    i++;
                        x[i+1]=x[i]+30;
                        y[i+1]=y[i];
                    i++;
                        x[i+1]=x[i];
                        y[i+1]=y[i]-30;
                    break;
                case 4:
                    //Inverse T shape
                    x[i+1]=x[i]-30;
                    y[i+1]=y[i]+30;
                    for(i = 1;i<3;i++)
                    {
                        x[i+1]=x[i]+30;
                        y[i+1]=y[i];
                    }
                    break;
                case 5:
                    //S shape
                    x[i+1]=x[i]-30;
                    y[i+1]=y[i]+30;
                    i++;
                    x[i+1]=x[i]+30;
                    y[i+1]=y[i];
                    i++;
                    x[i+1]=x[i]+30;
                    y[i+1]=y[i]-30;
                    break;
                case 6:
                    //Z shape
                    x[i+1]=x[i]+30;
                    y[i+1]=y[i];
                    i++;
                    x[i+1]=x[i];
                    y[i+1]=y[i]+30;
                    i++;
                    x[i+1]=x[i]+30;
                    y[i+1]=y[i];
                    break;

        }
        g.setColor(Color.BLACK);
        for(i=0;i<4;i++)
        {
            g.fillRect(x[i], y[i], 30, 30);
        }


    }

    public void keyReleased(KeyEvent e){;}
     public void keyTyped(KeyEvent e){;}

    public void keyPressed(KeyEvent e) 
    {
        System.out.println("Kkk "+e.getKeyCode());
        if(e.getKeyCode() == KeyEvent.VK_LEFT)
     {
        if(xpos>=30)
        {
            xpos=xpos-30;
        }
        System.out.println("xpos is :" + xpos);
     }
     if(e.getKeyCode() == KeyEvent.VK_RIGHT)
     { 
         xpos=xpos+30;
     }

     if(e.getKeyCode() == KeyEvent.VK_DOWN || e.getKeyCode() == KeyEvent.VK_SPACE)
     {
         ypos=420;
     }
 }
}

TIA

回答1:

Your code only draws a single block. You must store the coordinates of all generated block and redraw them at every game frame.

来源：https://stackoverflow.com/questions/14433321/how-to-settle-an-an-image-in-applet-for-tetris-game