Optimize for Android (Go edition): Lessons from Google apps - Part 1

Approach

• Always add framework/library updates after analyzing the changes and verifying its impact early on.
• Make sure to release memory before assigning new value to a pointer pointing to other object allocation in heap in Java. (native backend java objects) 

ClassA obj = new ClassA("x"); // ... something obj = new ClassB("y");

GC should clean this up eventually.

if ClassA allocates native resources underneath and doesn't cleanup automatically on finalize(..) and requires caller to call some release(..)  method, it needs to be like this 

ClassA obj = new ClassA("x"); // ... something // Explicit cleanup. obj.release(); obj = new ClassB("y");

else it will leak native heap memory. 

• Optimize your bitmaps: Large images/drawables usually consume more memory in the app. Google apps identified and optimized large bitmaps that are used in their apps. 

• Prefer Lazy/on-demand initializations of big drawables.
• Release view when necessary.
• Avoid using full colored bitmaps when possible. 

// Creating the bitmap for trails. trailBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ALPHA_8); ... // Setup paint for trails. trailPaint.setColorFilter(new ColorMatrixColorFilter(new ColorMatrix(new float[] {   0, 0, 0, 0, (color >> 16) & 0xFF,   0, 0, 0, 0, (color >> 8) & 0xFF,   0, 0, 0, 0, color & 0xFF,   0, 0, 0, 1, 0 }))); ... // onDraw @Override protected void onDraw(Canvas canvas) {   super.onDraw(canvas);   if (trailBitmap != null) {     canvas.drawBitmap(trailBitmap, 0, 0, trailPaint);   } }

A screenshot of glide typing on Gboard

• Check and only set the alpha channel for the bitmap for complex custom views used in the app. This saved them a couple of MBs (per screen size/density).
• While using Glide, 
• The ARGB_8888 format has 4 bytes/pixel consumption while RGB_565 has 2 bytes/pixel. Memory footprint gets reduced to half when RGB_565 format is used but using lower bitmap quality comes with a price too. Whether you need alpha values or not, try to fit your case accordingly.
• Configure and use cache wisely when using a 3P lib like Glide for image rendering.
• Try to choose other options for GIFs in your app when building for Android (Go edition) as GIFs take a lot of memory.
• The aapt tool can optimize the image resources placed in res/drawable/ with lossless compression during the build process. For example, the aapt tool can convert a true-color PNG that does not require more than 256 colors to an 8-bit PNG with a color palette. Doing so results in an image of equal quality but a smaller memory footprint. Read more here.
• You can reduce PNG file sizes without losing image quality using tools like pngcrush, pngquant, or zopflipng. All of these tools can reduce PNG file size while preserving the perceptive image quality.
• You could use resizable bitmaps. The Draw 9-patch tool is a WYSIWYG editor included in Android Studio that allows you to create bitmap images that automatically resize to accommodate the contents of the view and the size of the screen. Learn more about the tool here. 

Recap

• Optimize for Android (Go edition): Lessons from Google apps – Part 1
• Optimize for Android (Go edition): Lessons from Google apps – Part 2
• Optimize for Android (Go edition): Lessons from Google apps – Part 3