Basic game loop

Byron KiourtzoglouNovember 11th, 2012Last Updated: February 16th, 2013

0 81 2 minutes read

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.

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