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I wrote two methods to check there performance public class Test1 { private String value; public void notNull(){ if( value != null) { //do something } } public void nullNot(){ if( null != value) { //do something } } } and checked it's byte code after compiling public void notNull(); Code: Stack=1, Locals=1, Args_size=1 0: aload_0 1: getfield #2; //Field value:Ljava/lang/String; 4: ifnull 7 7: return LineNumberTable: line 6: 0 line 9: 7 StackMapTable: number_of_entries = 1 frame_type = 7 /* same */ public void nullNot(); Code: Stack=2, Locals=1, Args_size=1 0: aconst_null 1: aload_0 2: getfield #2; //Field value:Ljava/lang/String; 5: if_acmpeq 8 8: return LineNumberTable: line 12: 0 line 15: 8 StackMapTable: number_of_entries = 1 frame_type = 8 /* same */ } in here two opcodes are used to implement the if condition: in first case it use ifnull- check top value of stack is null-, and in second case it use if_acmpeq- check top two value are equal in the stack- so, will this make an effect on performance? (this will helps me to prove first implementation of null is good in performance wise as well as in the aspect of readability :) )

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