Java List Interface

List Interface is the subinterface of Collection. It contains index-based methods to insert and delete elements. It is a factory of ListIterator interface.

List Interface declaration

1. public interface List<E> extends Collection<E>  

Methods of Java List Interface

Method	Description
void add(int index, E element)	It is used to insert the specified element at the specified position in a list.
boolean add(E e)	It is used to append the specified element at the end of a list.
boolean addAll(Collection<? extends E> c)	It is used to append all of the elements in the specified collection to the end of a list.
boolean addAll(int index, Collection<? extends E> c)	It is used to append all the elements in the specified collection, starting at the specified position of the list.
void clear()	It is used to remove all of the elements from this list.
boolean equals(Object o)	It is used to compare the specified object with the elements of a list.
int hashcode()	It is used to return the hash code value for a list.
E get(int index)	It is used to fetch the element from the particular position of the list.
boolean isEmpty()	It returns true if the list is empty, otherwise false.
int lastIndexOf(Object o)	It is used to return the index in this list of the last occurrence of the specified element, or -1 if the list does not contain this element.
Object[] toArray()	It is used to return an array containing all of the elements in this list in the correct order.
T[] toArray(T[] a)	It is used to return an array containing all of the elements in this list in the correct order.
boolean contains(Object o)	It returns true if the list contains the specified element
boolean containsAll(Collection<?> c)	It returns true if the list contains all the specified element
int indexOf(Object o)	It is used to return the index in this list of the first occurrence of the specified element, or -1 if the List does not contain this element.
E remove(int index)	It is used to remove the element present at the specified position in the list.
boolean remove(Object o)	It is used to remove the first occurrence of the specified element.
boolean removeAll(Collection<?> c)	It is used to remove all the elements from the list.
void replaceAll(UnaryOperator operator)	It is used to replace all the elements from the list with the specified element.
void retainAll(Collection<?> c)	It is used to retain all the elements in the list that are present in the specified collection.
E set(int index, E element)	It is used to replace the specified element in the list, present at the specified position.
void sort(Comparator<? super E> c)	It is used to sort the elements of the list on the basis of specified comparator.
Spliterator spliterator()	It is used to create spliterator over the elements in a list.
List<E> subList(int fromIndex, int toIndex)	It is used to fetch all the elements lies within the given range.
int size()	It is used to return the number of elements present in the list.

Java List Example

1. import java.util.*;  
2. public class ListExample{  
3. public static void main(String args[]){  
4. List<String> al=new ArrayList<String>();  
5. al.add("Amit");  
6. al.add("Vijay");  
7. al.add("Kumar");  
8. al.add(1,"Sachin");  
9. System.out.println("An element at 2nd position: "+al.get(2));  
10. for(String s:al){  
11.  System.out.println(s);  
12. }  
13. }  
14. }  

Output:

An element at 2nd position: Vijay
Amit
Sachin
Vijay
Kumar

Java ListIterator Interface

ListIterator Interface is used to traverse the element in a backward and forward direction.

ListIterator Interface declaration

1. public interface ListIterator<E> extends Iterator<E>  

Methods of Java ListIterator Interface:

Method	Description
void add(E e)	This method inserts the specified element into the list.
boolean hasNext()	This method returns true if the list iterator has more elements while traversing the list in the forward direction.
E next()	This method returns the next element in the list and advances the cursor position.
int nextIndex()	This method returns the index of the element that would be returned by a subsequent call to next()
boolean hasPrevious()	This method returns true if this list iterator has more elements while traversing the list in the reverse direction.
E previous()	This method returns the previous element in the list and moves the cursor position backward.
E previousIndex()	This method returns the index of the element that would be returned by a subsequent call to previous().
void remove()	This method removes the last element from the list that was returned by next() or previous() methods
void set(E e)	This method replaces the last element returned by next() or previous() methods with the specified element.

Example of ListIterator Interface

1. import java.util.*;  
2. public class ListIteratorExample1{  
3. public static void main(String args[]){  
4. List<String> al=new ArrayList<String>();    
5.         al.add("Amit");    
6.         al.add("Vijay");    
7.         al.add("Kumar");    
8.         al.add(1,"Sachin");    
9.         ListIterator<String> itr=al.listIterator();    
10.         System.out.println("Traversing elements in forward direction");    
11.         while(itr.hasNext()){    
12.               
13.         System.out.println("index:"+itr.nextIndex()+" value:"+itr.next());    
14.         }    
15.         System.out.println("Traversing elements in backward direction");    
16.         while(itr.hasPrevious()){    
17.           
18.         System.out.println("index:"+itr.previousIndex()+" value:"+itr.previous());    
19.         }    
20. }  
21. }  

Output:

Traversing elements in forward direction
index:0 value:Amit
index:1 value:Sachin
index:2 value:Vijay
index:3 value:Kumar
Traversing elements in backward direction
index:3 value:Kumar
index:2 value:Vijay
index:1 value:Sachin
index:0 value:Amit

Example of ListIterator Interface: Book

1. import java.util.*;  
2. class Book {  
3. int id;  
4. String name,author,publisher;  
5. int quantity;  
6. public Book(int id, String name, String author, String publisher, int quantity) {  
7.     this.id = id;  
8.     this.name = name;  
9.     this.author = author;  
10.     this.publisher = publisher;  
11.     this.quantity = quantity;  
12. }  
13. }  
14. public class ListIteratorExample2 {  
15. public static void main(String[] args) {  
16.     //Creating list of Books  
17.     List<Book> list=new ArrayList<Book>();  
18.     //Creating Books  
19.     Book b1=new Book(101,"Let us C","Yashwant Kanetkar","BPB",8);  
20.     Book b2=new Book(102,"Data Communications & Networking","Forouzan","Mc Graw Hill",4);  
21.     Book b3=new Book(103,"Operating System","Galvin","Wiley",6);  
22.     //Adding Books to list  
23.     list.add(b1);  
24.     list.add(b2);  
25.     list.add(b3);  
26.     //Traversing list  
27.     for(Book b:list){  
28.     System.out.println(b.id+" "+b.name+" "+b.author+" "+b.publisher+" "+b.quantity);  
29.     }  
30. }  
31. }  

Output:

101 Let us C Yashwant Kanetkar BPB 8
102 Data Communications & Networking Forouzan Mc Graw Hill 4
103 Operating System Galvin Wiley 6