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Code Analyzer for Java

There is a newer version: 8.10.0.38194

Why is this an issue?
Assuming that a comparator or compareTo method always returns -1 or 1 if the first operand is less than or greater than the second is
incorrect.
The specifications for both methods, Comparator.compare and Comparable.compareTo, state that their return value is "a
negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object." Even if a specific
comparator always returns -1, 0, or 1, this is only an implementation detail, not the API contract developers can rely on.
How to fix it
Replace

   == -1 with < 0 (the first operand is less than the second) 
   == 1 with > 0 (the first operand is greater than the second) 
   != -1 with >= 0 (the first operand is greater than or equal to the second) 
   != 1 with <= 0 (the first operand is less than or equal to the second) 

Code examples
Noncompliant code example
public class Main {

  boolean isAGreaterThanB(Comparable<Integer> a, Integer b) {
    return a.compareTo(b) == 1; // Noncompliant, check for constant return value
  }

  public static void main(String[] args) {
    ByteComparator comparator = new ByteComparator();
    if (comparator.compare((byte) 23, (byte) 42) == -1) { // Noncompliant, check for constant return value
      System.out.println("23 < 42");
    } else {
      System.out.println("23 >= 42");
    }
  }

  static class ByteComparator implements Comparator<Byte> {
    @Override
    public int compare(Byte a, Byte b) {
      return a - b;
    }
  }
}

Compliant solution
public class Main {

  boolean isAGreaterThanB(Comparable<Integer> a, Integer b) {
    return a.compareTo(b) > 0; // Compliant, check for positive return value
  }

  public static void main(String[] args) {
    ByteComparator comparator = new ByteComparator();
    if (comparator.compare((byte) 23, (byte) 42) < 0) { // Compliant, check for negative return value
      System.out.println("23 < 42");
    } else {
      System.out.println("23 >= 42");
    }
  }

  static class ByteComparator implements Comparator<Byte> {
    @Override
    public int compare(Byte a, Byte b) {
      return a - b;
    }
  }
}

Resources
Documentation

   Java SE 8 API Specification:
  Comparable.compareTo 
   Java SE 8 API Specification: Comparator.compare