Why doesn’t the android clear the memory after completing the activity?

Question

In my case, I have tow functions called A (Main Activity) and B (Child Activity). A will launch B (B having some files for uploading images using the Glide image library).

If I get the memory allocation using the Android memory monitor, I can clearly see that the memory allocation is increasing. This is completely normal, because we are doing some image-related stuff in B.Image Attached.

So, my problem is that if I clicked the back button in Activity B, it will go to Activity A, and the allocated memory will not be cleared. The memory allocation will be the same.

Is this normal Android behavior?

If not, how can I manually clear the memory?

GC , : (.

B

    @Override
    protected void onDestroy() {
       super.onDestroy();
       System.gc();
    }

Answer 1

1) OnDestroy finish();, , .

2) System.gc(); onDestroy , activity B OnDestroy. , activity B .

3) , OnDestroy, // .. ( )

. System.gc(); , GC . . : System.gc()?