title: ' ... != null' or 'null != ....' best performance?
body: <p>I wrote two methods to check there performance</p>
  
  <pre><code> public class Test1 {
  
   private String value;
  
   public void notNull(){
    if( value != null) {
      //do something
    }
  }
  
  public void nullNot(){
   if( null != value) {
    //do something
   }
  }
  
  }
  </code></pre>
  
  <p>and checked it's byte code after compiling</p>
  
  <pre><code>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 */
  
  
  }
  </code></pre>
  
  <p>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-</p>
  
  <p>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 :) )</p>