android Array by drawable resources with onClick event

Question

ok so I have my array, im calling my array, but it doesn't update the background of the canvas? what am I doing wrong? perhaps some tutorial links would be helpful here. Thanks.

             int[] myImageList = {
            R.drawable.lettersa, R.drawable.lettersb,
            R.drawable.lettersc, R.drawable.lettersd,
            R.drawable.letterse, R.drawable.lettersf, R.drawable.lettersg,
            R.drawable.lettersh, R.drawable.lettersi, R.drawable.lettersj,
            R.drawable.lettersk, R.drawable.lettersl, R.drawable.lettersm,
            R.drawable.lettersn, R.drawable.letterso, R.drawable.lettersp,
            R.drawable.lettersq, R.drawable.letterss, R.drawable.letterst,
            R.drawable.lettersu, R.drawable.lettersv, R.drawable.lettersw,
            R.drawable.lettersx, R.drawable.lettersy, R.drawable.lettersz};


                 mNextBtn.setOnClickListener(new OnClickListener() {
                    public void onClick(View v) {
                        // TODO Auto-generated method stub
                        int i;
                        if (mNextBtn.equals(mNextBtn)) {

                            for   (i=0;i<myImageList.length;i++)
                            {
                                         mSCanvas.setBackgroundResource(i);
                            }

                            return;
                        }   

                        mNextBtn.setEnabled(mSCanvas.isUndoable());
                        }

                });

Basically I want the canvas background to change to the next letter to trace upon click of the button — baron dune
– baron dune, Commented Mar 26, 2013 at 14:30
I really did not get your question, after this code what is happening now and why you have an if condition inside click handler if (mNextBtn.equals(mNextBtn)) like this ? — Triode
– Triode, Commented Mar 26, 2013 at 14:34
Also you need to call invalidate() at the view that you draw the canvas in. This forces the view to redraw with the changed canvas. — Thommy
– Thommy, Commented Mar 26, 2013 at 14:36

Sam · Accepted Answer · 2013-03-26 14:34:14Z

1

Basically I want the canvas background to change to the next letter to trace upon click of the button

I recommend a different approach:

mNextBtn.setOnClickListener(new OnClickListener() {
    int i = 0;
    public void onClick(View v) {
        mSCanvas.setBackgroundResource(myImageList[i]);
        i++;
        if(i >= myImageList.length)
             i = 0;

        // I'm not sure what you want to do here, so I left it:
        mNextBtn.setEnabled(mSCanvas.isUndoable());
        return;
    }
});

I changed three main points:

Only set one background resource at a time, the loop sets every background resource in a few milliseconds and always leaves you with the last value.
The drawable resource is myImageList[i] not i in mSCanvas.setBackgroundResource()
I don't know of any situation when this mNextBtn.equals(mNextBtn) is false...

answered Mar 26, 2013 at 14:34

Sam

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2 Comments

baron dune Over a year ago

worked like a charm thanks. and I wanted to leave the button unclickable unless something was drawn.

baron dune Over a year ago

it worked, but then I had a problem with the resource not changing because the background was already 0, so I changed int i = 1 and it works and loops through correctly. Thanks for the awesome help

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