//Midlet.java
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;
public class Midlet extends MIDlet{
public void startApp(){
Display.getDisplay(this).setCurrent(new canvas());
}
public void pauseApp(){}
public void destroyApp(boolean r){}
}

//canvas.java
class canvas extends Canvas{
//nhan vat chinh co toa do x,y va key k dung de dieu khien
int w,h,x,y,k=0;
//co bien thoi gian di chuyen lan cuoi, de tranh viec di qua nhanh
long lm=0;
//tao bien nhan vat tu dong
AI ai;
public canvas(){
setFullScreenMode(true);
w=getWidth();
h=getHeight();
x=0;
y=0;
//tao ra nhan vat tu dong co toa do la cuoi man hinh w, h
ai=new AI(w,h);
}
public void paint(Graphics g){
//di chuyen nhan vat theo k
move();
//to man hinh
g.setColor(0);
g.fillRect(0, 0, w, h);
//chon mau do cho nhan vat, ve nhan vat
g.setColor(0xf00000);
g.fillRect(x, y, 8, 8);
//ve nhan vat tu dong
ai.paint(g,x,y);
repaint();
}
public void keyPressed(int k){
this.k=k;
}
public void keyReleased(int k){
this.k=0;
}
void move(){
//kiem tra neu nhu lan di chuyen cuoi cung voi hien tai neu cach nhau 100milis giay, thi cho di chuyen tiep
if(lm lm=System.currentTimeMillis();
switch(k){
case -1:
y-=4;
break;
case -2:
y+=4;
break;
case -3:
x-=4;
break;
case -4:
x+=4;
break;
}
}
}
}

//AI.java
class AI{
int x,y;
long lm=0;
public AI(int x,int y){
//cho cac toa do vao nhan vat tu dong
this.x=x;
this.y=y;
}
public void paint(Graphics g,int ax,int ay){
//di chuyen dua vao toa do cua nhan vat chinh
move(ax,ay);
//ve nhan vat tu dong
g.setColor(0x00f0);
g.fillRect(x, y, 8, 8);
}
void move(int ax,int ay){
//cung chinh thoi gian di chuyen, cach khoang la 100 milis giay
if(lm lm=System.currentTimeMillis();
x+=ai(x,ax);
y+=ai(y,ay);
}
}
int ai(int a,int b){
//ham nay dung de xac dinh xem nen: tien, lui, hay giu nguyen toa do, bang cach so sanh giua hai toa do
return a>b?-1: (a==b)?0:1;
//nếu a>b thì trả lại -1(lùi), ngược lại nếu a==b thì trả lại 0(giữ nguyên tọa độ), ngược lại nữa thì 1(tiến)
}
}