Which keyword is used to declare a generic class in Java?
Q.703Easy
What will be the output of the following code?
List<String> list = new ArrayList<>();
list.add("Java");
System.out.println(list.get(0).length());
Q.704Easy
Which of the following is a valid generic method declaration?
Q.705Medium
What is type erasure in Java Generics?
Advertisement
Q.706Medium
Which statement about wildcard generics (?) is correct?
Q.707Medium
What will happen when you try to create an array of generics?
List<String>[] array = new List<String>[10];
Q.708Medium
Consider the code:
List<? extends Number> list = new ArrayList<>();
list.add(5); // Will this compile?
Q.709Medium
Which of the following represents a bounded type parameter?
Q.710Medium
What is the difference between List<?> and List<Object>?
Q.711Medium
Consider this generic interface:
interface Comparable<T> { int compareTo(T o); }
Which class definition correctly implements this?
Q.712Medium
What will be the output?
List<Integer> list = new ArrayList<>();
list.add(10);
Object obj = list.get(0);
System.out.println(obj instanceof Integer);
Q.713Hard
Which of these correctly demonstrates the Producer Extends Consumer Super (PECS) principle?
Q.714Hard
What will happen with this code?
List list = new ArrayList<String>();
list.add(123); // Adding Integer
String s = (String) list.get(0);
Q.715Hard
Consider this code:
public <T extends Comparable<T>> T getMax(T a, T b) {
return a.compareTo(b) > 0 ? a : b;
}
What is the benefit of this recursive bound <T extends Comparable<T>>?
Q.716Easy
What is the output of this generic code?
class Pair<K, V> {
public void display(K key, V value) {
System.out.println(key + ": " + value);
}
}
Pair<String, Integer> p = new Pair<>();
p.display("Age", 25);
Q.717Hard
Which statement is true about generic inheritance?
Q.718Hard
What will be the result of this code?
List<String> list = new ArrayList<>();
list.add("Hello");
List raw = list; // Unchecked assignment
raw.add(123); // Adding Integer to raw type
String s = list.get(1);
Q.719Medium
Which of these declarations would NOT cause a compilation warning or error?
Q.720Easy
In Java generics, what does the wildcard '?' represent?
