Question

I am trying to implement the get color method for the cwac color mixer( https://github.com/commonsguy/cwac-colormixer), but every time this code runs I get a NullPointerException:

int color = 1;

public void openColor(){
ColorMixer mixer = (ColorMixer)findViewById(R.id.mixer);
  if (color!=1){
    mixer.setColor(color);
  }
  color = mixer.getColor();
}

The color = mixer.getColor(); is the line that crashes.

Answer 1

I haven’t ever used this Commonsware component before, but from looking at the source code, it appears all you need to do is set up a listener/callback. This mechanism will allow you to get notified of any changes in the color picking.

First, have your class implement the following listener interface:

public interface OnColorChangedListener {
    public void onColorChange(int argb);
}

Then set the listener on the ColorMixer using:

public void setOnColorChangedListener(OnColorChangedListener listener) {
    this.listener=listener;
}

If you do it all inline, it will look somewhat like this:

mixer.setOnColorChangeListener(new ColorMixer.OnColorChangeListener() {
    @Override public void onColorChange(int argb) {
        //... get the color here; e.g.
        color = argb;
    }
});