Difference between == and equals in java?

Answer 1

== is a primitive equals operator.

meaning, you can only compare primitive data types with it (int, float, string, ...)

when working with objects such as objects of your own class or another objects (Integer, Double, ....) you can override the equals method to make comparison between objects

why would one need such functionality you might ask?

consider the following code

Integer x1 = new Integer(5);
Integer y1 = new Integer(5);

int x2 = 5;
int y2 = 5;

so what would be the result of:
System.out.println(x1 == y1);
System.out.println(x2 == y2);

answer would be *false* for the first print and *true* for the second one

the reason behind this is that the == operator checks object *references* when comparing objects (non-primitives)

therefore, the result would be different references for the newly instantiated Integer objects

when comparing primitives, the values are checked

and if you were to do:
System.out.println(x1.equals(y1));

the equals operator would compare the values inside the objects to return the value *true*.

a much briefer explanation in here 😅
https://www.sololearn.com/discuss/270604/?ref=app

Answer 2

The operator == is to compare only primitive data types.
Strings are reference types:
- reference on the Stack
- value on the Heap

For String comparison use the 'equals()' method.

If you compare Strings with the == operator, you compare their references, not their values.

Assume this:
String a = "string";
String b = "string";

System.out.println(a == b); // true

Looks like it works, but that's because the JVM checks, whether the String b value already exists in the String pool, and if it's found, the String b will get the same reference as the String a. That's, to save memory.

But here, the == operator will fail:

String a = "string";
String b = new String("string");

System.out.println(a == b); // false

That's simply, because we allocate new different address on the Heap for that value, so the reference on the Stack of String b now will be different from String a.

Answer 3

== to test equality of condition
= is the assignment operator

Answer 4

== returns a boolean value of either true or false = assigns a value to a variable.
equals() also functions as ==