The type parameter G is hiding the type G

public class MyGenericClass< G> {


    public <G> G genericMethod1(G g){
        System.out.println(g.toString());
        return g;

    }

    public <X> G genericMethod2(G g) {
        System.out.println(g.toString());
        return g;
    }

    public <X> X genericMethod3(G g) {
        System.out.println(g.toString());
        Integer i = new Integer(100);
        return (X) i;       
    }


    public static void main(String... cmdarg) {

        MyGenericClass<Employee> gemp = new MyGenericClass<Employee>();
        Employee e1 = new Employee();
        e1.setName("My Name");


        String resultOfMethod3 = gemp.genericMethod3(e1);
        System.out.println(resultOfMethod3);                            

    }


}

in genericMethod1: I get the compiler warning as "The type parameter G is hiding the type G".

Question: Which G is hidden by this G? What's the actual meaning of this?

genericMethod2 doesn't show any errors/warnings.

Question: I thought it should not compile. why is two different types allowed in same method signature? What can be typical real time example to compare with G and X?

In genericMethod3: I'm intentionally returning an Integer object and in the main method i'm trying to assign the result to a String. As expected: I got the ClassCastException.

Question: Isn't the original purpose of having generics to avoid ClassCastExceptions? Why did the compiler allow it? Is this a bug in the design of Generics?

Copyright Notice：Content Author:「Jinnah」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/32820133/the-type-parameter-g-is-hiding-the-type-g