CODEWITHSUNDEEP
javaeclipseequals
sotn
sotn

Reputation: 2101

Eclipse auto generated equals() method

In eclipse's auto generated equals method, the first line compares reference equality 

if(this == obj) return true;

As far as I know == is not really an equality check, it only checks if 2 references point to the same memory location. So why is it used?

Upvotes: 0

Views: 874

Answers (2)

Glenn Lane
Glenn Lane

Reputation: 4010

It's incredibly fast to check reference equality, so they might as well get it out of the way before moving on to more aggressive comparisons.

Upvotes: 1

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 279910

Say you have two references

Foo foo = new Foo("some value", " many parameter", 1, 2, 3, 5); 
Foo foo2 = foo;

if (foo2.equals(foo))
    // do something

Where Foo is a class with a bunch of fields that all need to be equal for object equality.

Comparing for reference equality early on saves you from having to check each field on the referenced objects because they are guaranteed to be equal.

Upvotes: 3

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