Equality in Java

One of the few methods that comes with all Java classes is equals(). By convention, it tests for MEANINGFUL equality. Therefore, this code


Integer i1 = new Integer(5);
Integer i2 = new Integer(5);

boolean test1 = i1.equals(i2);
boolean test2 = i2.equals(i1);


should produce true for both calls.

On the other hand, the equality operator (==) tests to see whether two references actually point at the same object. It "simply looks at the bits in the variable, and they're either identical or they're not" -K. Sierra & B. Bates, SCJP Sun Certified Programmer for Java 6 Study Guide (Exam 310-065). So, the values in the previous example would be false, but this code:


Integer i1 = new Integer(5);
Integer i2 = i1;

boolean test = i1 == i2;


will produce true.