How to draw lots of bitmaps on screen in an Android game without slow performance

Question

I want to make a tile based game for android. At the moment I am drawing each tile as a separate bitmap. I have a big for loop that reads from a string and draws different

Answer 1

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MapLoader extends SurfaceView implements SurfaceHolder.Callback,
    Runnable {

SurfaceHolder holder;
Thread thread;

Bitmap grass = BitmapFactory.decodeResource(getResources(),
        R.drawable.tilemapdemo);
boolean running = false;

int[][] grassCoords = new int[][] { { 0, 16, 32, 48, 64 },
        { 0, 16, 32, 48, 64 }, { 0, 16, 32, 48, 64 },
        { 0, 16, 32, 48, 64 }, { 0, 16, 32, 48, 64 } };

public MapLoader(Context context, int width, int height) {
    super(context);

    holder = getHolder();
    holder.addCallback(this);
}

public MapLoader(Context context, AttributeSet attrs) {
    super(context, attrs);

    holder = getHolder();
    holder.addCallback(this);
}

public MapLoader(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    holder = getHolder();
    holder.addCallback(this);
}

public void pause() {
    running = false;

    while (running) {
        try {
            thread.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        break;
    }
    thread = null;
}

public void resume() {
    running = true;
    thread = new Thread(this);
    thread.start();

}

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

    running = true;
    thread = new Thread(this);
    thread.start();

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    Canvas c = holder.lockCanvas();
    draw(c);
    holder.unlockCanvasAndPost(c);

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {

}

@Override
public void run() {

    while (running == true) {

        // performs drawing to the canvas
        if (!holder.getSurface().isValid()) {

            continue;
        }

        Canvas c = holder.lockCanvas();

        int x = 0;
        int y = 0;

        for (x = 0; x < grassCoords.length; x += grass.getWidth()) {

            for (y = 0; y < grassCoords.length; y += grass.getHeight()) {

                c.drawBitmap(grass, x, y, null);
            }

        }

        holder.unlockCanvasAndPost(c);

    }

}

}