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.
Noncompliant code example
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
Exceptions
- This rule ignores
*, +, and =.
- The specific case of testing a floating point value against itself is a valid test for
NaN and is therefore ignored.
- Similarly, left-shifting 1 onto 1 is common in the construction of bit masks, and is 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
