The collections class of Java has various methods that can be used to initialize the list. For stack, double brace initialization is used in which the add method is called during the instantiation itself. ArrayList, LinkedList, and Stack.ĪrrayList and LinkedList objects are instantiated and then the add methods are called to add elements to these objects. This program has three different list declarations i.e. Let’s implement a program in Java that shows the creation and initialization of the list using the asList method. This is as shown below: List listname = new ArrayList (Arrays.asList(array_name)) If you want the list to be mutable, then you have to create an instance of the list using new and then assign the array elements to it using the asList method. The above statement creates an immutable list. Here, the data_type should match that of the array. The general syntax is: List listname = Arrays.asList(array_name) You can create an immutable list using the array values. The method asList () is already covered in detail in the Arrays topic. You can make use of any of the methods given below to initialize a list object. From the above statements, you can make out that the order of elements will change depending on the class used for creating an instance of the list.įor Example, for a list with stack class, the order is Last In, First Out (LIFO). Hence you can declare and create instances of the list in any one of the following ways:Īs shown above, you can create a list with any of the above classes and then initialize these lists with values. We have already stated that List is an interface and is implemented by classes like ArrayList, Stack, Vector and LinkedList. To include the functionality of the list interface in your program, you will have to import the package java.util.* that contain list interface and other classes definitions as follows: import java.util.* Create & Declare List Hence, when you have to implement list Interface, you can implement any of the above list type class depending on the requirements. Stack, LinkedList, ArrayList, and Vector. Thus there are four types of lists in Java i.e.
The classes LinkedList, Stack, Vector, ArrayList, and CopyOnWriteArrayList are all the implementation classes of List interface that are frequently used by programmers. The class AbstractList provides the skeletal implementation of the List interface.
Java List Class DiagramĪs shown in the above class diagram, the Java list interface extends from the Collection interface of java.util package which in turn extends from the Iterable interface of the java.util package. Given below is a class diagram of the Java List interface. This is the standard interface that inherits the Collection interface of Java. The Java List interface is a sub-type of the Java Collection interface.
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