making bitmap's specific color transparent

Question

Friends, I have an andrid application to display an image on another. the second image's white colour should be converted in to transparent. so i used two imageviews. the original image to be overlayed is bitmap1. image after making transparent is bitmap2. when i run this i got some exceptios atsetPixel method. the code is shown below

Bitmap bitmap2 = null;
int width = imViewOverLay.getWidth();
int height = imViewOverLay.getHeight();
for(int x=0;x<width;x++)
{
    for(int y=0;y<height;y++)
    {
        if(bitMap1.getPixel(x, y) == Color.WHITE)
        {
            bitmap2.setPixel(x, y, Color.TRANSPARENT);
        }
        else
        {
            bitmap2.setPixel(x, y, bitMap1.getPixel(x, y));
        }
    }
}

imViewOverLay is the imageview of the over lay image. anybody please help me to know the mistakes in above code

Answer 1

The most obvious error is that you're not creating bitmap2 - unless you've not posted all the code of course.

You declare it and set it to null, but then don't do anything else until you try to call bitmap2.setPixel.