How many collection classes are there in java with example

How many collection classes are there in java with example

I'm happy to help you with that!

Java has five built-in collection classes: List, Set, Map, Queue, and Deque.

    import java.util.ArrayList;
public class Main {
public static void main(String[] args) {
ArrayList fruits = new ArrayList<>();
fruits.add("Apple");
fruits.add("Banana");
fruits.add("Orange");
System.out.println(fruits);  // [Apple, Banana, Orange]
}
}

    import java.util.HashSet;
public class Main {
public static void main(String[] args) {
HashSet fruits = new HashSet<>();
fruits.add("Apple");
fruits.add("Banana");
fruits.add("Apple");  // This won't be added as the set doesn't allow duplicates.
System.out.println(fruits);  // [Apple, Banana]
}
}

    import java.util.HashMap;
public class Main {
public static void main(String[] args) {
HashMap<String, Integer> fruits = new HashMap<>();
fruits.put("Apple", 1);
fruits.put("Banana", 2);
System.out.println(fruits);  // {Apple=1, Banana=2}
}
}

    import java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList fruits = new LinkedList<>();
fruits.add("Apple");
fruits.add("Banana");
System.out.println(fruits.poll());  // Apple
}
}

    import java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList fruits = new LinkedList<>();
fruits.add("Apple");
fruits.add("Banana");
System.out.println(fruits.removeFirst());  // Apple
}
}

Remember, Java has many other collection classes and interfaces available as well.

How many collection classes are there in java javatpoint

I'd be happy to help you with that!

In Java, there are four types of collection classes: List, Set, Map, and Queue.

List: A list is an ordered collection of objects. It allows duplicate values, and the order in which elements were added is preserved. There are two main implementations of the List interface: ArrayList and LinkedList. The difference between them lies in their underlying data structure:

Set: A set is an unordered collection of objects. It does not allow duplicate values, and the order in which elements were added is not preserved. The Set interface has two main implementations: HashSet and TreeSet. The difference between them lies in their underlying data structure:

Map: A map is an unordered collection of key-value pairs. It does not allow duplicate keys, but it can have duplicate values. The Map interface has two main implementations: HashMap and TreeMap. The difference between them lies in their underlying data structure:

Queue: A queue is a first-in, first-out (FIFO) collection class. It does not allow duplicate values, and the order in which elements were added is preserved. The Queue interface has two main implementations: LinkedList and PriorityQueue. The difference between them lies in their underlying data structure:

These four types of collection classes provide a range of ways to store, manipulate, and retrieve collections of objects in Java.

In addition to these core interfaces, there are many other specialized collection classes, such as:

Each of these collection classes has its own strengths and weaknesses, and the choice of which one to use depends on the specific requirements of your application.