Question: I want to change the background color for layouts dynamically for the first time only, using configuration file in android that file should be in assets folder,it can be xml file or anything.
please help me.

Answer: 
**Using a tmp variable is both faster *and* more readable with modern compilers and CPUs**. 2x loads into registers, then 2x stores back into the original locations.

Or if one or both variables were already in registers, the compiler might completely optimize anyway the temporary. If xor-swapping was faster on some hypothetical machine, a good compiler would use it for you when optimizing `tmp = a; a = b; b = tmp;` So you don't need to write it explicitly. This is why you're using C, not writing by hand in asm.

Also, xor-swap works for integers only. What if you want to swap floating-point numbers? Strings? Custom objects? etc.
All answers are already there consider it just an addition-

->if both values goes for same memory address-result will be zero

->compilers can optimize away the temporary variable in the naive swap

->modern CPUs strive to execute instructions in parallel via instruction pipelines
but with XOR technique is considerably slower than using a temporary variable to do swapping because each operation depends on the result of previous

->x+Y may go for integer overflow