ComparesVsEquals.java

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Objects;

public class EqualsVsCompare {
  private static boolean notCompares(Charset a, Charset b) {
    return !(a == b) && (a == null || b == null || a.compareTo(b) != 0);
  }

  private static boolean notEquals(Charset a, Charset b) {
    return !Objects.equals(a, b);
  }

  public static void main(String[] args) {
    Charset one = null;
    Charset two = StandardCharsets.UTF_8;

    assert notCompares(one, two);
    assert notCompares(two, one);
    assert !notCompares(one, one);
    assert !notCompares(two, two);
    assert notCompares(two, StandardCharsets.UTF_16);

    assert notEquals(one, two);
    assert notEquals(two, one);
    assert !notEquals(one, one);
    assert !notEquals(two, two);
    assert notEquals(two, StandardCharsets.UTF_16);
  }
}