JAVA UTIL MCQs

Which of these standard collection classes implements a dynamic array?

Which of these class can generate an array which can increase and decrease in size automatically?

Which of these method can be used to increase the capacity of ArrayList object manually?

Which of these method of ArrayList class is used to obtain present size of an object?

Which of these methods can be used to obtain a static array from an ArrayList object?

Which of these method is used to reduce the capacity of an ArrayList object?

What is the output of this program

    import java.util.*;
    class Arraylist 
    {
        public static void main(String args[]) 
        {
            ArrayList obj = new ArrayList();
            obj.add("A");
            obj.add("B");
            obj.add("C");
            obj.add(1, "D");
            System.out.println(obj);
        }
    }

What is the output of this program

    import java.util.*;
    class Output 
    {
        public static void main(String args[]) 
        {
            ArrayList obj = new ArrayList();
            obj.add("A");
            obj.add(0, "B");
            System.out.println(obj.size());
        }
    }

Map implements collection interface?

Which of the below does not implement Map interface?

What is the premise of equality for IdentityHashMap?

What happens if we put a key object in a HashMap which exists?

While finding the correct location for saving key value pair, how many times the key is hashed?

Is hashmap an ordered collection.

If two threads access the same hashmap at the same time, what would happen?

How to externally synchronize hashmap?

What is the output of below snippet?

public class Demo
{
  public static void main(String[] args)
  {
  Map<Integer, Object> sampleMap = new TreeMap<Integer, Object>();
  sampleMap.put(1, null); 
  sampleMap.put(5, null); 
  sampleMap.put(3, null); 
  sampleMap.put(2, null); 
  sampleMap.put(4, null); 
 
       System.out.println(sampleMap);
   }
}

If large number of items are stored in hash bucket, what happens to the internal structure?

How can we remove an object from ArrayList?

How to remove duplicates from List?