LinkedList addAll(Collection) in Java

addAll(Collection): This method is available in java.util.LinkedList class of Java.

Syntax:

boolean java.util.LinkedList.addAll(Collection<? extends K> c)

This method takes one argument. This method appends all of the elements in the specified collection to the end of this list.

Parameters: One parameter is required for this method.

c: a collection containing elements to be added to this list.

Returns: true if this list changed as a result of the call.

Throws:

NullPointerException - if the specified collection is null

Approach 1: When no exception

Java

import java.util.LinkedList;

public class LinkedListaddAll {
    public static void main(String[] args) {

        LinkedList<Integer> linkedList = new LinkedList<>();

        linkedList.add(1);
        linkedList.add(2);
        LinkedList<Integer> linkedList2 = new LinkedList<>();

        linkedList2.addAll(linkedList);

        System.out.println(linkedList2);
    }
}

Output:

[1, 2]

Approach 2: NullPointerException 

Java

import java.util.LinkedList;

public class LinkedListaddAll {
    public static void main(String[] args) {

        LinkedList<Integer> linkedList = null;
        LinkedList<Integer> linkedList2 = new LinkedList<>();

        linkedList2.addAll(linkedList);

        System.out.println(linkedList2);
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.util.Collection.toArray()" because "c" is null
	at java.base/java.util.LinkedList.addAll(LinkedList.java:412)
	at java.base/java.util.LinkedList.addAll(LinkedList.java:391)
	

Some other methods of LinkedList 

add(K): This method appends the specified element to the end of this list.

add(int, K): This method inserts the specified element at the specified position in this list.

addAll(int, Collection): This method inserts all of the elements in the specified collection into this list, starting at the specified position.

addFirst(K): This method inserts the specified element at the beginning of this list.

addLast(K e): This method appends the specified element to the end of this list.

clear(): This method removes all of the elements from this list.

clone(): This method returns a shallow copy of this LinkedList.

contains(Object): This method returns true if this list contains the specified

containsAll(Collection): This method returns true if this collection contains all of the elements in the specified collection.

descendingIterator(): This method returns an iterator over the elements in this deque in reverse sequential order.

element(): This method retrieves but does not remove, the head (first element) of this list.

equals(Object): his method compares the specified object with this list for equality.

forEach(Consumer): This method performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception.

get(int): This method returns the element at the specified position in this list.

getFirst(): This method returns the first element in this list.

getLast(): This method returns the last element in this list.

hashCode(): This method returns the hash code value for this list.

indexOf(Object): This method returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.

isEmpty(): This method returns true if this collection contains no elements.

iterator(): This method returns an iterator over the elements in this list.

lastIndexOf(Object): This method returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.

listIterator(): This method returns a list iterator over the elements in this list.

listIterator(int): This method returns a list-iterator of the elements in this list starting at the specified position in the list.

offer(K): This method adds the specified element as the tail (last element) of this list.

offerFirst(K): This method inserts the specified element at the front of this list.

offerLast(K): This method inserts the specified element at the end of this list.

parallelStream(): This method returns a possibly parallel Stream with this collection as its source.

peek(): This method retrieves but does not remove, the head (first element) of this list.

peekFirst(): This method retrieves, but does not remove, the first element of this list, or returns null if this list is empty.

peekLast(): This method retrieves, but does not remove, the last element of this list, or returns null if this list is empty.

poll(): This method retrieves and removes the head (first element) of this list.

pollFirst(): This method retrieves and removes the first element of this list, or returns null if this list is empty.

pollLast(): This method retrieves and removes the last element of this list, or returns null if this list is empty.

pop(): This method pops an element from the stack represented by this list.

push(K e): This method pushes an element onto the stack represented by this list.

remove(): This method retrieves and removes the head (first element) of this list.

remove(int): This method removes the element at the specified position in this list.

remove(Object): This method removes the first occurrence of the specified element from this list if it is present.

removeAll(Collection): This method removes all of this collection's elements that are also contained in the specified collection.

removeFirst(): This method removes and returns the first element from this list.

removeFirstOccurrence(Object): This method removes the first occurrence of the specified element in this list.

removeIf(Predicate): This method removes all of the elements of this collection that satisfy the given predicate.

removeLast(): This method removes and returns the last element from this list.

removeLastOccurrence(Object): This method removes the last occurrence of the specified element in this list.

replaceAll(UnaryOperator): This method replaces each element of this list with the result of applying the operator to that element.

retainAll(Collection): This method retains only the elements in this collection that are contained in the specified collection.

set(int, K): This method replaces the element at the specified position in this list with the specified element.

size(): This method returns the number of elements in this list.

sort(Comparator): This method sorts this list according to the order induced by the specified Comparator.

spliterator(): This method creates a late-binding and fail-fast Spliterator over the elements in this list.

stream(): This method returns a sequential Stream with this collection as its source.

subList(int, int): This method returns a view of the portion of this list between the specified fromIndex, inclusive, and toIndex, exclusive.

toArray(): This method returns an array containing all of the elements in this list in proper sequence (from the first to the last element).

toArray(IntFunction): This method returns an array containing all of the elements in this collection, using the provided generator function to allocate the returned array.

toArray(K[]): This method returns an array containing all of the elements in this list in proper sequence (from first to the last element); the runtime type of the returned array is that of the specified array.

toString(): This method returns a string representation of this collection.