Using the same value on either side of a binary operator is almost always a mistake. In the case of logical operators, it is either a copy/paste error and therefore a bug, or it is simply wasted 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.
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
=.