ripper234 ripper234 - 3 months ago 7
Java Question

Getting default value for java primitive types

I have a java primitive type at hand:

Class c = int.class; // or long.class, or boolean.class


I'd like to get a 'default value' for this class - specifically the value is assigned to fields of this type if they are not initialized. E.g., '0' for a number, 'false' for a boolean.

Is there a generic way to do this? I tried

c.newInstance()


But I'm getting an InstantiationException, and not a default instance.

Answer

The Guava Libraries already contains that:
http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/base/Defaults.html

Calling defaultValue will return the default value for any primitive type (as specified by the JLS), and null for any other type.

Use it like so:

import com.google.common.base.Defaults;
Defaults.defaultValue(Integer.TYPE); //will return 0