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javacasting

Is there a form of "type safe" casting in Java?

Suppose I have two classes deriving from a third abstract class:

public abstract class Parent{
    public Parent(){
    }
}

public class ChildA extends Parent {
    public ChildA {
    }
}

public class ChildB extends Parent {
    public ChildB {
    }
}

In C# I could handle casting in a somewhat type safe manner by doing:

ChildA child = obj as ChildA;

Which would make child == null if it wasn't a ChildA type object. If I were to do:

ChildA child = (ChildA)obj;

...in C# this would throw an exception if the type wasn't correct.

So basically, is there a way to to do the first type of casting in Java? Thanks.

Solution

  • I can't think of a way in the language itself, but you can easily emulate it like this:

    ChildA child = (obj instanceof ChildA ? (ChildA)obj : null);