Question

This is the code I’m using to convert two colored pictures to grayscale and compare them pixel by pixel. My app keeps force closing though. here’s the code:

public boolean equals(Bitmap bitmap1, Bitmap bitmap2) {
        Bitmap grayscaleBitmap1 = Bitmap.createBitmap(
                bitmap1.getWidth(), bitmap1.getHeight(),
                Bitmap.Config.RGB_565);

            Canvas c = new Canvas(grayscaleBitmap1);
            Paint p = new Paint();
            ColorMatrix cm = new ColorMatrix();

            cm.setSaturation(0);
            ColorMatrixColorFilter filter = new ColorMatrixColorFilter(cm);
            p.setColorFilter(filter); 
            c.drawBitmap(bitmap1, 0, 0, p); 
            Bitmap grayscaleBitmap2 = Bitmap.createBitmap(
                    bitmap2.getWidth(), bitmap2.getHeight(),
                    Bitmap.Config.RGB_565);
            Canvas c1 = new Canvas(grayscaleBitmap2);
            c1.drawBitmap(bitmap2, 0, 0, p);    
        ByteBuffer buffer1 = ByteBuffer.allocate(grayscaleBitmap1.getHeight()
                * grayscaleBitmap1.getRowBytes());
        grayscaleBitmap1.copyPixelsToBuffer(buffer1);

        ByteBuffer buffer2 = ByteBuffer.allocate(grayscaleBitmap2.getHeight()
                * grayscaleBitmap2.getRowBytes());
        grayscaleBitmap2.copyPixelsToBuffer(buffer2);

        return Arrays.equals(buffer1.array(), buffer2.array());
    }

Here’s the logcat.

Answer 1

01-12 10:12:48.947: E/AndroidRuntime(2052): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
01-12 10:12:48.947: E/AndroidRuntime(2052):     at android.os.Handler.<init>(Handler.java:121)
01-12 10:12:48.947: E/AndroidRuntime(2052):     at android.widget.Toast.<init>(Toast.java:68)

These lines says that you have wrote Toast somewhere in your async Task.
please put your Toast into
runOnUiThread(); as i shown below :

  runOnUiThread(new Runnable() {        
            @Override
            public void run() {
            Toast.makeText(yourActivity.this, "your Text Here!",1000).show();                               
            }
    });

and you are done.