Basic game loop

This is an example of how to create a basic game loop with Android. Before following this basic game loop example, you might wish to check out our Android Game Development Tutorials series.

To create a basic game loop in Android one should perform the following steps:

• Create an Android activity (here called DroidzActivity)
• Implement the onCreate method
• Create a class that extends SurfaceView (here called MainGamePanel)
• Extend the Thread class (class here called MainThread)
• Implement the desired functionality inside the thread’s run method
• Start the thread from inside the SurfaceView class

These are demonstrated in the code snippet(s) below:

package net.obviam.droidz;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Window;
import android.view.WindowManager;

public class DroidzActivity extends Activity {
    /** Called when the activity is first created. */

 private static final String TAG = DroidzActivity.class.getSimpleName();

    @Override
    public void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);

  // requesting to turn the title OFF

  requestWindowFeature(Window.FEATURE_NO_TITLE);

  // making it full screen

  getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

  // set our MainGamePanel as the View

  setContentView(new MainGamePanel(this));

  Log.d(TAG, "View added");
    }

 @Override
 protected void onDestroy() {
  Log.d(TAG, "Destroying...");
  super.onDestroy();
 }

 @Override
 protected void onStop() {
  Log.d(TAG, "Stopping...");
  super.onStop();
 }
}

package net.obviam.droidz;

import android.util.Log;
import android.view.SurfaceHolder;

public class MainThread extends Thread {

 private static final String TAG = MainThread.class.getSimpleName();

 private SurfaceHolder surfaceHolder;
 private MainGamePanel gamePanel;
 private boolean running;
 public void setRunning(boolean running) {
  this.running = running;
 }

 public MainThread(SurfaceHolder surfaceHolder, MainGamePanel gamePanel) {
  super();
  this.surfaceHolder = surfaceHolder;
  this.gamePanel = gamePanel;
 }

 @Override
 public void run() {
  long tickCount = 0L;
  Log.d(TAG, "Starting game loop");
  while (running) {
   tickCount++;
   // update game state
   // render state to the screen
  }
  Log.d(TAG, "Game loop executed " + tickCount + " times");
 }
}

package net.obviam.droidz;

import android.content.Context;
import android.graphics.Canvas;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MainGamePanel extends SurfaceView implements
  SurfaceHolder.Callback {

 private MainThread thread;

 public MainGamePanel(Context context) {
  super(context);
  getHolder().addCallback(this);

  // create the game loop thread
  thread = new MainThread();

  setFocusable(true);
 }

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  thread.setRunning(true);
  thread.start();
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  boolean retry = true;
  while (retry) {
   try {
    thread.join();
    retry = false;
   } catch (InterruptedException e) {
    // try again shutting down the thread
   }
  }
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  return super.onTouchEvent(event);
 }

 @Override
 protected void onDraw(Canvas canvas) {
 }
}

 
This was an example of how to create a basic game loop with Android.

Related Article:

• Android Game Development – A Basic Game Loop

Reference: A Basic Game Loop from our JCG partner Tamas Jano at the “Against The Grain” blog.