Instanceof Operator in Java

The instanceof operator in java is used to test whether the object is an instance of the specified type (class or subclass or interface). The instanceof in java is also known as type comparison operator because it compares the instance with type. It returns either true or false. If we apply the instanceof operator with any variable that has null value, it returns false.

Lets see a simple program example –

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Output
cobj is instance of Child
cobj is instance of Parent
instanceof in java with a variable that have null value

If we apply instanceof operator with a variable that have null value, it returns false. Let’s see the example given below where we apply instanceof operator with the variable that have null value.

Output
false
Downcasting with java instanceof operator

upcasting vs downcasting in java

When Subclass type refers to the object of Parent class, it is known as downcasting. If we perform it directly, compiler gives Compilation error. If you perform it by typecasting, ClassCastException is thrown at runtime. But if we use instanceof operator, downcasting is possible.

Lets see a simple program example –

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Output
ok downcasting performed

4 thoughts on “Instanceof Operator in Java

  • May 14, 2018 at 1:55 pm
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    Greetings! I know this is kinda off topic but I was wondering which blog platform are you using for this site? I’m getting tired of WordPress because I’ve had problems with hackers and I’m looking at alternatives for another platform. I would be awesome if you could point me in the direction of a good platform.

    Reply
    • May 14, 2018 at 2:52 pm
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      Well yes this is definitely an off topic question on this article. I am not really aware of other platforms, maybe drupal or joomla. These are the only ones I just have heard of. All the best.

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  • May 26, 2018 at 7:35 pm
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    • May 27, 2018 at 1:29 pm
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      Thank you very much 🙂 Yes please do share it with your friends, that would be the best help for our website 🙂

      Reply

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