Java Strings: compareTo() vs. equals()

Question

When testing for equality of String's in Java I have always used equals() because to me this seems to be the most natural method for it. After all, its name already says what it is intended to do. However, a colleague of mine recently told me had been taught to use compareTo() == 0 instead of equals(). This feels unnatural (as compareTo() is meant to provide an ordering and not compare for equality) and even somewhat dangerous (because compareTo() == 0 does not necessarily imply equality in all cases, even though I know it does for String's) to me.

He did not know why he was taught to use compareTo() instead of equals() for String's, and I could also not find any reason why. Is this really a matter of personal taste, or is there any real reason for either method?

Answer 1

"equals" compare objects and return true or false and "compare to" return 0 if is true or an number [> 0] or [< 0] if is false here an example:

<!-- language: lang-java -->
//Objects Integer
Integer num1 = 1;
Integer num2 = 1;
//equal
System.out.println(num1.equals(num2));
System.out.println(num1.compareTo(num2));
//New Value
num2 = 3;//set value
//diferent
System.out.println(num1.equals(num2));
System.out.println(num1.compareTo(num2));

Results:

num1.equals(num2) =true
num1.compareTo(num2) =0
num1.equals(num2) =false
num1.compareTo(num2) =-1

Documentation Compare to: https://docs.oracle.com/javase/7/docs/api/java/lang/Comparable.html

Documentation Equals : https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#equals(java.lang.Object)