In Java, can I instantiate an anonymous subclass from a class object?

Question

I have a factory method that creates objects that will be used in unit tests. All these objects are made from one base class:

public static <T extends BaseEntity> T modMake(Class<T> clazz)
{
    try {
        return clazz.newInstance();
    } catch (InstantiationException e) {
        // Should never happen
        throw new AssertionError(e);
    } catch (IllegalAccessException e) {
        // Should never happen
        throw new AssertionError(e);
    }
}

Now I want to override the getter method from this base class, but only for tests. I usually do this with an anonymous class, for example ( Nodeis one of the subtypes BaseEntity):

public static Node nodMake()
{
    return new Node() {
        @Override
        public long ixGet() { return 1; }
    };
}

Can I do this in a function with an argument Classtoo?

Answer 1

Lose your factory method and use a mocking API like EasyMock to achieve the behavior you describe.

Then your code will look something like this:

long returnValue = 12;

Node nodeMock = createMock(Node.class);
expect(nodeMock.ixGet()).andReturn(returnValue);
replay(nodeMock);

//add test code here

verify(nodeMock);

, :

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Answer 2

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