Java: Can I convert List of Object to List of String[] and vice versa?

Question

Is this possible without going through the list and casting the objects?

I also need to convert List<Object> to List<T> (T = predefined Object) if it's possible?

Edit: for clarification, I'm trying to use List<Object> as a return type of a class method that is widely used in my code.

Answer 1

Actually, this is possible, because of type erasure. You can convert a parameterized type to a raw type, and vice-versa.

    List<Object> listO = new ArrayList<Object>( );
    listO.add( "Foo" );
    listO.add( "Bar" );

    List listQ = listO;
    List<String> listS = (List<String>) listQ;

However, this does not mean this is a good idea. This works around compile-time type-checking of parameterized types. If your List contains objects other than the type you expect, unexpected results may occur.

Answer 2

No. This is simply not a valid conversion, because not all Objects are String[].

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_{You could have determined this for yourself in 2 lines of code.}

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Edit

It sounds like you need to write the method more generically. Something like this:

public <T> List<T> getGenericList()
{
    return new ArrayList<T>();
}

This can return a List<String[]> like so:

List<String[]> listOfStringArr = getGenericList();