It depends a bit on when you were thinking of nulling the reference. If you have an object chain A->B->C, then once A is not reachable, A, B and C will all be eligible for garbage collection (assuming nothing else is referring to either B or C). There’s no need, and never has been any … Read more
In a talk at Google I/O 2013 (Writing Custom Views for Android), Romain Guy clarified the misunderstanding that caused everyone to start using RelativeLayouts for everything. A RelativeLayout always has to do two measure passes. Overall it is negligible as long as your view hierarchy is simple. But if your hierarchy is complex, doing an … Read more
The compiler can build jump tables where applicable. For example, when you use the reflector to look at the code produced, you will see that for huge switches on strings, the compiler will actually generate code that uses a hash table to dispatch these. The hash table uses the strings as keys and delegates to … Read more
Use SysInternal’s RAMMap app. The Empty / Empty Standby List menu option will clear the Windows file cache.
This answer is summarised from Loading large bitmaps Efficiently which explains how to use inSampleSize to load a down-scaled bitmap version. In particular Pre-scaling bitmaps explains the details of various methods, how to combine them, and which are the most memory efficient. There are three dominant ways to resize a bitmap on Android which have … Read more
Imagine a CPU that performs only 64 bit arithmetic operations. Now imagine how you would implement an unsigned 8 bit addition on such CPU. It would necessarily involve more than one operation to get the right result. On such CPU, 64 bit operations are faster than operations on other integer widths. In this situation, all … Read more
See the Wikipedia article on modular exponentiation. Basically, when you do a**d % n, you actually have to calculate a**d, which could be quite large. But there are ways of computing a**d % n without having to compute a**d itself, and that is what pow does. The ** operator can’t do this because it can’t … Read more
If your application is unused for a while it gets unloaded (from the server memory). On the first hit it gets loaded and stays loaded until some time passes without anyone accessing it. This is done to save server resources. If no one uses your app why keep resources busy and not let someone who … Read more
Although the Django docs recommend using count rather than len: Note: Don’t use len() on QuerySets if all you want to do is determine the number of records in the set. It’s much more efficient to handle a count at the database level, using SQL’s SELECT COUNT(*), and Django provides a count() method for precisely … Read more
The final keyword does not appear in the class file for local variables and parameters, thus it cannot impact the runtime performance. It’s only use is to clarify the coders intent that the variable not be changed (which many consider dubious reason for its usage), and dealing with anonymous inner classes. There is a lot … Read more