Learn Java: Manipulating Variables

So far, we’ve only been using operations on primitive types. It doesn’t make much sense to multiply Strings, or see if one String is less than the other. But what if we had two users logging into a site, and we wanted to see if their usernames were the same?

With objects, such as Strings, we can’t use the primitive equality operator. To test equality with objects, we use a built-in method called .equals(). When comparing objects, make sure to always use .equals(). == will work occasionally, but the reason why it sometimes works has to do with how objects are stored in memory.

For the purposes of this lesson (as well as good practice) remember to use .equals() instead of == when comparing objects.

To use it, we call it on one String, by using ., and pass in the String to compare against in parentheses:

String person1 = "Paul"; String person2 = "John"; String person3 = "Paul"; System.out.println(person1.equals(person2)); // Prints false, since "Paul" is not "John" System.out.println(person1.equals(person3)); // Prints true, since "Paul" is "Paul"



We have three lines from a song in Song.java.

First, print out whether line1 and line2 are the same.


Now, print whether line2 and line3 are equal.

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