public class GenericsType<T> {

private T t;

public T get(){
    return this.t;
}

public void set(T t1){
    this.t=t1;
}

public static void main(String args[]){
    GenericsType<String> type = new GenericsType<>();
    type.set("Pankaj"); //valid

    GenericsType type1 = new GenericsType(); //raw type
    type1.set("Pankaj"); //valid
    type1.set(10); //valid and autoboxing support
}
}

public interface MyInyerface<E> {
    void print(E e);
}

public class MyClass implements MyInyerface<String> {
    @Override
    public void print(String s) {

    }


    class MyClassInteger implements  MyInyerface<Integer>{

        @Override
        public void print(Integer integer) {

        }
    }
}

ArrayList&ltString> stringList = new ArrayList&ltString>(); // список строк
    ArrayList&ltInteger> intList = new ArrayList&ltInteger>();  // список чисел
    stringList.add("123");   // OK
    stringList.add(123);     // Ошибка!
    intList.add("123");   // Ошибка!
    intList.add(123);     // OK

class SomeClass < T > {
...
    private T value;
    public T getValue() { ... }
}

SomeClass< Integer > intInstance = new SomeClass< Integer >();
    SomeClass< ArrayList > listInstance = new SomeClass< ArrayList>();
    ....
    int i = intInstance.getValue(); // OK
    int j = listInstance.getValue(); // Error!!!
    ArrayList list = listInstance.getValue(); // OK