Interpretation of Java documentation: Functional analysis of the getLast() method of the LinkedList class

Java Document Interpretation: Function Analysis of the getLast() Method of the LinkedList Class

LinkedList is one of the commonly used data structures in Java. It is a linked list structure that supports Random access, insertion, deletion and other operations, and the getLast() method is a very important method in the LinkedList class. This method is used to get the last element in the linked list. This article will analyze the specific functions of the getLast() method and provide relevant code examples.

1. Function of getLast() method

The getLast() method is used to obtain the last element in the LinkedList and return the element. The return value of this method is of type Object, so corresponding cast type conversion is required when using it. For specific usage, please refer to the following code example:

LinkedList<String> list = new LinkedList<>();
list.add("Java");
list.add("Python");
list.add("C++");
String lastElement = (String) list.getLast();

In the above example code, a LinkedList object list of type String is first created, and then three elements are added to the linked list. Then, the expression "(String) list.getLast()" calls the getLast() method in the LinkedList class, converts the return value to the String type, and finally assigns the result to the lastElement variable.

2. Source code analysis of the getLast() method in the LinkedList class

At the source code level, the getLast() method of the LinkedList class actually calls the getLast() method of the doubly linked list. The specific code is as follows:

public E getLast() {
    final Node<E> l = last;
    if (l == null)
        throw new NoSuchElementException();
    return l.item;
}

In this source code, a final type Node object l is first defined, which is a reference to the last element node in the LinkedList list. Then use an if statement to determine whether the last element is empty. If it is empty, a NoSuchElementException is thrown; otherwise, the value stored in the element node is returned.

In actual applications, the getLast() method of the LinkedList class is very practical, especially when it is necessary to obtain the last element of the linked list. Through the analysis of this method, we have a deeper understanding of the underlying implementation principle of the LinkedList class.

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