如何在Android上计算位图的Java哈希图的大小

Question

I have created a hahsmap of bitmap objects in my android service, using an int as key. To this, I am adding different bitmaps created dynamically, as per requirement. Can I find the RAM/heap memory footprint added to my service because of this hashmap (including the size of bitmaps), using some tool, or programatically.

If anybody has worked in this area before, please help !

Answer 1

Well with bitmaps it's pretty simple because they're bitmaps, huge swaths of memory, if you're using rgb8 format (1 byte per colour) then it is height*width*3 bytes big + Java's overhead (~24 bytes is a safe assumption)+ other stuff in class (8*method count at least)

Anyway the bitmap will be the big thing.

The hasmap itself will be somewhere around 16*number of things in it big + Java's overhead + other stuff in class.

It's hard with Java because there's no concept of ownership, nor size (everything is a reference) so you need to be careful not to count stuff twice....

Anyway the killer is the bitmap the rest is sufficiently small to neglect.

As I thought though:

final int   getAllocationByteCount()
Returns the size of the allocated memory used to store this bitmap's pixels.
final int   getByteCount()
Returns the minimum number of bytes that can be used to store this bitmap's pixels.

From

http://developer.android.com/reference/android/graphics/Bitmap.html

Answer 2

You can run through values in Map and compute each bitmap's memory with

HashMap<?, Bitmap> bitmaps;

long total = 0;

for (Bitmap bmp : bitmaps.values()) {
    total += bmp.getRowBytes() * bmp.getHeight() * 4; // 4 is bytes per pixel in ARGB_8888 mode
}

Answer 3

您可以转储堆并使用Eclipse内存分析器（MAT）来获取您感兴趣的所有对象的大小