failing to add/remove bitmap to object

Question

I have an Object lets call it "A" that has an ArrayList<B>. The object B holds a Bitmap. When I iterate through my ArrayList<B> to grab the Bitmaps from each B Object there is only one type. I've done some testing and I am definitely putting in different Bitmaps, but somewhere my logic is flawed and I am overwriting the all Bitmaps with the last Bitmap in my ArrayList<B>.

Java

private A createObject() {
    A a = new A(); // create object A
    ArrayList<B> bList = new ArrayList<B>(); //create array list which will hold B objects
    RelativeLayout rel = (RelativeLayout)findViewById(R.id.rel);
    LinearLayout lin = new LinearLayout(this);
    lin.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

    a.setName(UUID.randomUUID().toString());

    for (LinkedHashMap.Entry<String, ArrayList<Circle>> entry : mCordHashMap.entrySet()) {
        ArrayList<Circle> coords = new ArrayList<Circle>();
        B b = new B(); //create new B object
        coords = entry.getValue();
        Path path = new Path();
        String key = entry.getKey();
        String surfaceName = getSurfaceFromKey(key);

        b.setName(surfaceName);

        for (Circle c : coords) {
            if (c == coords.get(0)) {
                path.moveTo(c.getmX(), c.getmY());
            } else {
                path.lineTo(c.getmX(), c.getmY());
            }
        }

        path.close();
        mCanvas.drawPath(path, mPaint);
        mImageView.invalidate();

        b.setRegion(mBitmap); // add bitmap to B
        bList.add(b); // add B to list
    }

    a.setBList(bList); // add the list of B objects to object A here
    ArrayList<B> testList = a.getBList();

    for (B b : testList) {
        Bitmap bmp = b.getRegion().createScaledBitmap(b.getRegion(), 100, 100, false);
        ImageView iv = new ImageView(this);
        iv.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
        iv.setImageBitmap(bmp);
        lin.addView(iv);
    }
    rel.addView(lin);

    return a;
}

Now all of this works, just not as intended. I get ImageViews with the same Bitmap in each of them.

So it looks like this

[a] [a] [a] [a]

However theBitmaps that go in are different. For instance if I change where I add my views, the outcome is as desired.

2nd example

private A createObject() {
    A a = new A(); // create object A
    ArrayList<B> bList = new ArrayList<B>(); //create array list which will hold B objects
    RelativeLayout rel = (RelativeLayout)findViewById(R.id.rel);
    LinearLayout lin = new LinearLayout(this);
    lin.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

    a.setName(UUID.randomUUID().toString());

    for (LinkedHashMap.Entry<String, ArrayList<Circle>> entry : mCordHashMap.entrySet()) {
        ArrayList<Circle> coords = new ArrayList<Circle>();
        B b = new B(); //create new B object
        coords = entry.getValue();
        Path path = new Path();
        String key = entry.getKey();
        String surfaceName = getSurfaceFromKey(key);

        b.setName(surfaceName);

        for (Circle c : coords) {
            if (c == coords.get(0)) {
                path.moveTo(c.getmX(), c.getmY());
            } else {
                path.lineTo(c.getmX(), c.getmY());
            }
        }

        path.close();
        mCanvas.drawPath(path, mPaint);
        mImageView.invalidate();

        // DIFFERENCE   
        Bitmap bmp = mBitmap.createScaledBitmap(mBitmap, 100, 100, false);
        ImageView iv = new ImageView(this);
        iv.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
        iv.setImageBitmap(bmp);
        lin.addView(iv);

        b.setRegion(mBitmap); // add bitmap to B
        bList.add(b); // add B to list
    }
    rel.addView(lin);

    a.setBList(bList); // add the list of B objects to object A here    

    return a;
    }

This code shows ImagevViews with unique Bitmaps inside, as desired, like this

[a] [b] [c] ...

Why? Where am I losing the logic?

Answer 1

You probably use same copy of Bitmap, which is wrong. Remember that by adding a Bitmap to a List, you don't create a copy, but place the actual bitmap. And you place many times the same bitmap!

The correct solution is using a new Bitmap every time. This is a hint

List<Bitmap> list = new ArrayList<Bitmap>();

for (...) {
    Bitmap bmp = Bitmap.createBitmap(width, height, Config.ARGB_8888);
    Canvas canv = new Canvas(bmp);

    /* Draw on canvas */

    list.add(bmp);
}

Or, you may use bmp.copy(...) you you want to avoid replicating the drawing.