North education learning Example 1 Free Rolling Ball

Today, I have no intention of seeing the works I made when I used to study the j2_game in beijiao. They are all basic entry-level things and they were all running on the simulator, I have never tested it with a real machine. I think it's a bit hard. After reading the code, I thought some of the ideas I had when implementing them were somewhat clever. So I planned to spend some time sorting out the previous works one by one.

Since I had only been studying for half a year, and most of them were just exercises assigned by the instructors after class, I wrote these simple and rough articles, so don't expect too much. Of course, I will try to reoptimize and improve it, and give detailed comments. I hope that my friends who are interested in and haven't gotten started can get a better result after reading it.

This was written when I first learned the canvas interface. It mainly draws circles, sets colors, and controls the changes of object coordinates.

 

Finally:

 

 

 

Paste the code below

 

Gamemidlet class:

Package rollball; </P> <p> Import javax. microedition. MIDlet. MIDlet; <br/> Import javax. microedition. lcdui. *; <br/>/** <br/> * @ author kf156 (Asian Day) <br/> */<br/> public class gamemidlet extends MIDlet {<br/> Private Static gamemidlet instance; </P> <p> private gamecanvas game; </P> <p> Public gamemidlet () {<br/> instance = this; <br/>}</P> <p> protected void destroyapp (Boolean arg0) {<br/>}</P> <p> protected void pauseapp () {<br/>}</P> <p> protected void Startapp () {<br/> If (game = NULL) {<br/> game = new gamecanvas (); <br/>}< br/> display. getdisplay (this ). setcurrent (game); <br/>}</P> <p> Public static void quitapp () {<br/> instance. destroyapp (true); <br/> instance. policydestroyed (); <br/> instance = NULL; <br/>}< br/>

 

Gamecanvas class

 Package rollball; </P> <p> Import javax. microedition. lcdui. canvas; <br/> Import javax. microedition. lcdui. graphics; </P> <p>/** <br/> * freely scrolling ball <br/> * @ author kf156 (Asian Day) <br/> */<br/> public class gamecanvas extends canvas implements runnable {<br/> Public thread; </P> <p> Public Boolean running = true; </P> <p> Public int width, height, ballx = 0, Bally = 0, and ballangle = 0; </P> <p> private final int diameter = 40; // ball diameter </P> <p> Public int [] Key = new int [4]; </P> <p> private final int distance = 5; // The distance from each movement </P> <p> private final int angle = 12; // The angle of each rotation </P> <p> Public final static int key_up =-1; // up </P> <p> Public final static int key_down =-2; // down </P> <p> Public final static int key_left =-3; // left </P> <p> Public final static int key_right =-4; // right </P> <p> Public gamecanvas () {<br/> setfullscreenmode (true); <br/> startthread (); <br/> Init (); <br/>}</P> <p> Public void free () {<br/>}</P> <p> Public void Init () {<br/> width = getwidth (); <br/> Height = getheight (); <br/>}</P> <p> Public void input () {// judge <br/> key [0] = Key [2]; <br/> key [1] = Key [3]; <br/> key [2] = 0; <br/>}</P> <p> Public void Update () {</P> <p> switch (Key [1]) {</P> <p> case key_up: <br/> bally-= distance; <br/> ballangle + = angle; <br/> If (bally <-diameter) <br/> bally = height; <br/> break; <br/> case key_down: <br/> bally + = distance; <br/> ballangle-= angle; <br/> If (bally> height) <br/> bally =-diameter; <br/> break; <br/> case key_left: <br/> ballx-= distance; <br/> ballangle + = angle; <br/> If (ballx <-diameter) <br/> ballx = width; <br/> break; <br/> case key_right: <br/> ballx + = distance; <br/> ballangle-= angle; <br/> If (ballx> width) <br/> ballx =-diameter; <br/> break; </P> <p >}</P> <p> protected void paint (Graphics g) {</P> <p> G. setcolor (0x000000); <br/> G. fillrect (0, 0, width, height); </P> <p> // positive ball <br/> G. setcolor (0x00ff00); <br/> G. fillarc (ballx, Bally, diameter, diameter, 0,360); </P> <p> G. setcolor (0x0000ff); <br/> G. fillarc (ballx, Bally, diameter, diameter, ballangle + 60, 60); <br/> G. fillarc (ballx, Bally, diameter, diameter, ballangle + 180, 60); <br/> G. fillarc (ballx, Bally, diameter, diameter, ballangle + 300, 60); </P> <p >}</P> <p> Public void startthread () {<br/> If (thread = NULL) {<br/> thread = new thread (this); <br/> thread. start (); <br/>}</P> <p> Public void run () {<br/> int DEBUG = 0; <br/> try {<br/> while (running) {<br/> long start = system. currenttimemillis (); <br/> input (); <br/> DEBUG = 1; <br/> Update (); <br/> DEBUG = 2; <br/> repaint (); <br/> servicerepaints (); <br/> thread. yield (); <br/> long end = system. currenttimemillis ()-start; <br/> If (end <50) <br/> thread. sleep (50-end); <br/>}< br/> gamemidlet. quitapp (); <br/>}catch (exception e) {<br/> system. err. println ("RUN error:" + E + "Debug:" + Debug ); <br/>}</P> <p> // when the key is pressed <br/> protected void keypressed (INT keycode) {<br/> key [2] = Key [3] = keycode; <br/>}</P> <p> // when the key is released <br/> Public void keyreleased (INT keycode) {<br/> key [3] = 0; <br/>}< br/>

 

 

The project has been uploaded, feel that the web page to see the inconvenient friends can also directly download: http://download.csdn.net/source/1569954