InstantiationException when using a generic java class

I would like to create a simulation containing an entity. There can be two kinds of entities, complex and simple ones. When I instantiate a simple simulation, I want the simple entity to be instantiated, and when I instantiate a complex simulation I want the complex entity to be instantiated.

Entities:

class ComplexEntity extends Entity {
    public ComplexEntity(){}
}

class SimpleEntity extends Entity  {
    public SimpleEntity(){}
}

class Entity {
    public Entity(){}
}

Simulations:

class ComplexSimulation extends Simulation<ComplexEntity>
{

    public ComplexSimulation() throws InstantiationException, IllegalAccessException {
        super(ComplexEntity.class);
    }

}

class SimpleSimulation extends Simulation<SimpleEntity>
{
    public SimpleSimulation() throws InstantiationException, IllegalAccessException
    {
        super(SimpleEntity.class);
    }
}

class Simulation<E extends Entity> {
    protected final E entity;

    public Simulation(Class<E> class1) throws InstantiationException, IllegalAccessException 
    {
        entity = class1.newInstance();
    }
}

The problem is that when I try to construct a ComplexSimulation:

ComplexSimulation c = new ComplexSimulation();

I get the following InstantiationException:

java.lang.InstantiationException: test.Test$ComplexEntity
at java.lang.Class.newInstance(Unknown Source)
at test.Test$Simulation.<init>(Test.java:55)
at test.Test$ComplexSimulation.<init>(Test.java:37)
at test.Test.go(Test.java:12)
at test.Test.main(Test.java:6)
Caused by: java.lang.NoSuchMethodException: test.Test$ComplexEntity.<init>()
at java.lang.Class.getConstructor0(Unknown Source)

The zero argument constructor cannot be the problem because my entities have them... Does anybody know what the problem can be?

The problem is that you're using inner classes. You cannot create an instance of an inner class without an instance of the outer class, not even if you call Class<InnerClass>.newInstance().

Just make these inner classes to be top classes and your example should work as expected.

If you really want/need to initialize non-static inner classes using reflection, see here: How to instantiate inner class with reflection in Java?