在不同布局中更改imageview的图像源

Question

I can't find a solution to this anywhere, I'm still quite new to programming so it might be a simple question.

In my MainActivity I take the position of a ViewPager . According to this position I want to change the source of an ImageView which is placed in a layout that will inflate in a service. But with my code I keep getting a NullPointerException . Do I need to declare the ImageView differently because it's in a different layout than the currently showed one?

 public void OnClick(View view) {


    pagenumber = viewPager.getCurrentItem();
    imageView = (ImageView) findViewById(R.id.filterview);

    switch (pagenumber){
        case 0: imageView.setImageResource(R.drawable.goghfilter);
            break;
        case 1: imageView.setImageResource(R.drawable.background3);
            break;

Thanks for any help!

Answer 1

Well remember that the class inflated with the layout will only find views in that layout, try to findById a view not in that layout will cause errors. To resolve this, define a custom layout inflater, inflate the layout with the image , then used that view inflated and perform a findById on it.

Answer 2

Try This:

 ImageView mImageView = (ImageView) MainActivity.this.getLayoutInflater().inflate(R.layout.layout,null).findViewById(R.id.imageView); mImageView.setImageResource(R.drawable.icon);