Java Generics Interview Questions

    Question 1: JAVA - Generics Basics

    What is the main purpose of Generics in Java?

    Question 2: JAVA - Generic Class

    Which of the following correctly defines a generic class?

    Question 3: JAVA - Generic Method

    Which syntax is correct for a generic method?

    Question 4: JAVA - Type Safety Example

    What will happen in this code?

    List list = new ArrayList();
list.add("Hello");
list.add(10);
String s = (String) list.get(1);
System.out.println(s);

    Question 5: JAVA - Wildcard ?

    What does the wildcard ? represent in generics?

    Question 6: JAVA - Upper Bounded Wildcard

    Which declaration is correct for a list of numbers (Integer, Double, etc.)?

    Question 7: JAVA - Lower Bounded Wildcard

    Which syntax is used for a generic type that can accept Integer or its supertypes?

    Question 8: JAVA - Generic Example Code

    What will this code print?

    class Box<T> {
    T value;
    Box(T value) { this.value = value; }
    T get() { return value; }
}
public class Test {
    public static void main(String[] args) {
        Box<String> b = new Box<>("Java");
        System.out.println(b.get());
    }
}

    Question 9: JAVA - Type Erasure

    How does Java implement generics internally?

    Question 10: JAVA - Multiple Type Parameters

    Which of the following correctly declares a generic class with two type parameters?