Using the same value on both sides of a binary operator is a code defect. In the case of logical operators, it is either a copy/paste error and, therefore, a bug, or it is simply duplicated code and should be simplified. In the case of bitwise operators and most binary mathematical operators, having the same value on both sides of an operator yields predictable results and should be simplified as well.
if ( a == a ) { // always true doZ(); } if ( a != a ) { // always false doY(); } if ( a == b && a == b ) { // if the first one is true, the second one is too doX(); } if ( a == b || a == b ) { // if the first one is true, the second one is too doW(); } int j = 5 / 5; //always 1 int k = 5 - 5; //always 0 c.equals(c); //always true
*
, +
, and =
. NaN
and is therefore ignored. float f; if(f != f) { //test for NaN value System.out.println("f is NaN"); } int i = 1 << 1; // Compliant int j = a << a; // Noncompliant
=
.