Here is an example for all six boolean comparison operators (<, ==, >, >=, !=, <=):
BigDecimal big10 = new BigDecimal(10);
BigDecimal big20 = new BigDecimal(20);
System.out.println(big10.compareTo(big20) < -1); // false
System.out.println(big10.compareTo(big20) <= -1); // true
System.out.println(big10.compareTo(big20) == -1); // true
System.out.println(big10.compareTo(big20) >= -1); // true
System.out.println(big10.compareTo(big20) > -1); // false
System.out.println(big10.compareTo(big20) != -1); // false
System.out.println(big10.compareTo(big20) < 0); // true
System.out.println(big10.compareTo(big20) <= 0); // true
System.out.println(big10.compareTo(big20) == 0); // false
System.out.println(big10.compareTo(big20) >= 0); // false
System.out.println(big10.compareTo(big20) > 0); // false
System.out.println(big10.compareTo(big20) != 0); // true
System.out.println(big10.compareTo(big20) < 1); // true
System.out.println(big10.compareTo(big20) <= 1); // true
System.out.println(big10.compareTo(big20) == 1); // false
System.out.println(big10.compareTo(big20) >= 1); // false
System.out.println(big10.compareTo(big20) > 1); // false
System.out.println(big10.compareTo(big20) != 1); // true