What is List interface in java

The List interface is a sub interface of Collection under java.util package . it’s index stars from zero (0) . The diagram represents, List interface and it’s implementations .


List interface List is an ordered collection , it allows both duplicates and null elements .

List interface we can search elements by index .

List interface It is not a synchronized collection , Use Collections.synchronizedList(List list)for synchronized List .




All methods of List interface :



List ‹generic type› ‹object name›= new <List implemented class name>‹generic type›(); or

Example for List interface :


Few more methods :

Method Name Returns Description
addAll(Collection) Boolean To add Collection of elements ( if they are not present).
containsAll(Collection) Boolean Returns true , if the List having all elements.
iterator() Iterator To iterate  List .
removeAll(Collection) boolean To Remove specified Collection of elements .
retainAll(Collection) boolean To Keep specified Collection of elements  .
toArray() Object[] It returns an array with all elements .
toArray(T[] t) T[] It returns specified array(ex:String[]) ,with all elements  .
listIterator() ListIterator To iterate List .

List interfaceSome of the List implementations prohibits to add null elements .

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