Mutable and Immutable Bitmap in

It's about the same difference as with String vs StringBuilder - String is immutable so you can't change its content (well at least not without any hacks), while for StringBuilder you can change its content.
类似于String同StringBuffer的区别，String的内容是不可变的，像str+="anythingelse";这种操作看上去改变了String的内容，实际上是创建了一个新的String（str+“anythingelse”）。而StringBuffer是可以直接改变其内容的。
Set Bitmap mutable or immutable:
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inMutable = true;//true:Mutable false:Immutable default:Immutable
Bitmap bp = BitmapFactory.decodeResource(getResources(), R.raw.white, opt);