How to cast an Object to an int

Question

How can I cast an Object to an int in java?

Answer 1

If you're sure that this object is an Integer :

int i = (Integer) object;

Or, starting from Java 7, you can equivalently write:

int i = (int) object;

Beware, it can throw a ClassCastException if your object isn't an Integer and a NullPointerException if your object is null.

This way you assume that your Object is an Integer (the wrapped int) and you unbox it into an int.

int is a primitive so it can't be stored as an Object, the only way is to have an int considered/boxed as an Integer then stored as an Object.

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If your object is a String, then you can use the Integer.valueOf() method to convert it into a simple int :

int i = Integer.valueOf((String) object);

It can throw a NumberFormatException if your object isn't really a String with an integer as content.

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Resources :

• Oracle.com - Autoboxing
• Oracle.com - Primitive Data types

On the same topic :

• Java: What's the difference between autoboxing and casting?
• Autoboxing: So I can write: Integer i = 0; instead of: Integer i = new Integer(0);
• Convert Object into primitive int