任何动画的最基本的前提，是要在足够快的时间内显示和更换一张张的图片，让人的眼睛看到动的画面效果。图片必须按照顺序画出来。从一张图片到下一张图片之间的变化越小，效果会越好。

首先要做的，是使用你的图片处理软件（比如ps或者firework）创建一系列相同大小的图片来组成动画。每张图片代表动画一帧。

你需要制作一定数量的祯－－越多的帧会让你的动画看上去越平滑。制作好的图片一定要保存成PNG(Portable Network Graphics) 格式，MIDP唯一支持的图片格式；（有两个办法让你刚做好的图片在MIDlet上变成动画。第一，把图片都放到一个web服务器上，让MIDlet下载他们，MIDP内置的HTTP支持。第二个办法更简单，把图片用MIDlet打包成jar文件。如果你使用的是J2ME开发工具，把PNG文件放在你的项目文件里面就可以了。

动画的过程其实更像帐本记录：显示当前帧，然后适当地更换到下一帧。那么使用一个类来完成这个工作应该是很恰当的，那好，我们就先定义一个AnimatedImage类：

import java.util.*;
import javax.microedition.lcdui.*;
// 定义了一个动画，该动画其实只是一系列相同大小的图片
// 轮流显示，然后模拟出的动画
public class AnimatedImage extends TimerTask {;
private Canvas canvas;
private Image[] images;
private int[][] clipList;
private int current;
private int x;
private int y;
private int w;
private int h;

// Construct an animation with no canvas.

public AnimatedImage( Image[] images ){;
this( null, images, null );
};

// Construct an animation with a null clip list.

public AnimatedImage( Canvas canvas, Image[]
images ){; this( canvas, images, null );
};

// Construct an animation. The canvas can be null,
// but if not null then a repaint will be triggered
// on it each time the image changes due to a timer
// event. If a clip list is specified, the image is
// drawn multiple times, each time with a different
// clip rectangle, to simulate transparent parts.

public AnimatedImage( Canvas canvas, Image[] images,
int[][] clipList ){;
this.canvas = canvas;
this.images = images;
this.clipList = clipList;

if( images != null && clipList != null ){;
if( clipList.length < images.length ){;
throw new IllegalArgumentException();
};
};

if( images != null && images.length > 0 ){;
w = images[0].getWidth();
h = images[0].getHeight();
};
};

// Move to the next frame, wrapping if necessary.

public void advance( boolean repaint ){;
if( ++current >= images.length ){;
current = 0;
};

if( repaint && canvas != null && canvas.isShown()
){;
canvas.repaint( x, y, w, h );
canvas.serviceRepaints();
};
};

// Draw the current image in the animation. If
// no clip list, just a simple copy, otherwise
// set the clipping rectangle accordingly and
// draw the image multiple times.

public void draw( Graphics g ){;
if( w == 0 || h == 0 ) return;

int which = current;

if( clipList == null || clipList[which] == null
){;
g.drawImage( images[which], x, y,
g.TOP | g.LEFT );
}; else {;
int cx = g.getClipX();
int cy = g.getClipY();
int cw = g.getClipWidth();
int ch = g.getClipHeight();

int[] list = clipList[which];

for( int i = 0; i + 3 <= list.length; i +=
4 ){;
g.setClip( x + list[0], y + list[1],
list[2], list[3] );
g.drawImage( images[which], x, y,
g.TOP | g.LEFT );
};

g.setClip( cx, cy, cw, ch );
};
};

// Moves the animation's top left corner.

public void move( int x, int y ){;
this.x = x;
this.y = y;
};

// Invoked by the timer. Advances to the next frame
// and causes a repaint if a canvas is specified.

public void run(){;
if( w == 0 || h == 0 ) return;

advance( true );
};
};