Runtime casting: the class being converted must be itself or must inherit from it. : Reference Type Casting « Type Casting « SCJP

1. SCJP
2. Type Casting
3. Reference Type Casting

public class MainClass {
  public static void main(String[] argv) {
    MyClass[] myClassArray = new MyClass[3];
    MySubclass[] mySubclassArray = new MySubclass[3];

    myClassArray = (MyClass[]) mySubclassArray;

    System.out.println();
  }
}

class MyClass {
}

class MySubclass extends MyClass {
}