Java Deque getLast()方法

Deque接口 的 getLast() 方法返回Deque的最后一个元素或尾部。它并不删除该元素。当Deque为空时，它会抛出一个异常。

语法

E getLast()

参数： 该方法不接受任何参数。

返回： 该方法返回最后一个元素或Deque的尾部，但不删除它。

异常： 当Deque为空时，该函数会抛出NoSuchElementException，该函数被调用。

下面的程序说明了Deque的getLast()方法。

程序1： 在 LinkedList 的帮助下 。

// Java Program Demonstrate getLast()// method of Dequeimport java.util.*;  public class GFG {    public static void main(String[] args)        throws IllegalStateException    {          // create object of Deque        Deque<Integer> DQ            = new LinkedList<Integer>();          // Add numbers to end of Deque        DQ.add(7855642);        DQ.add(35658786);        DQ.add(5278367);        DQ.add(74381793);          // print Deque        System.out.println("Deque: " + DQ);          // print head        System.out.println("Deque's head: " + DQ.getLast());    }}

输出:

Deque: [7855642, 35658786, 5278367, 74381793]Deque's head: 74381793

程序2： 在 ArrayDeque 的帮助下，
。

// Java Program Demonstrate getLast()// method of Dequeimport java.util.*;  public class GFG {    public static void main(String[] args)        throws IllegalStateException    {          // create object of Deque        Deque<Integer> DQ            = new ArrayDeque<Integer>();          // Add numbers to end of Deque        DQ.add(7855642);        DQ.add(35658786);        DQ.add(5278367);        DQ.add(74381793);          // print Deque        System.out.println("Deque: " + DQ);          // print head        System.out.println("Deque's head: " + DQ.getLast());    }}

输出:

Deque: [7855642, 35658786, 5278367, 74381793]Deque's head: 74381793

程序3： 在 ConcurrentLinkedDeque 的帮助下，
。

// Java Program Demonstrate getLast()// method of Dequeimport java.util.*;import java.util.concurrent.ConcurrentLinkedDeque;  public class GFG {    public static void main(String[] args)        throws IllegalStateException    {          // create object of Deque        Deque<Integer> DQ            = new ConcurrentLinkedDeque<Integer>();          // Add numbers to end of Deque        DQ.add(7855642);        DQ.add(35658786);        DQ.add(5278367);        DQ.add(74381793);          // print Deque        System.out.println("Deque: " + DQ);          // print head        System.out.println("Deque's head: " + DQ.getLast());    }}

输出:

Deque: [7855642, 35658786, 5278367, 74381793]Deque's head: 74381793

程序4： 在 LinkedBlockingDeque 的帮助下，
。

// Java Program Demonstrate getLast()// method of Dequeimport java.util.*;import java.util.concurrent.LinkedBlockingDeque;  public class GFG {    public static void main(String[] args)        throws IllegalStateException    {          // create object of Deque        Deque<Integer> DQ            = new LinkedBlockingDeque<Integer>();          // Add numbers to end of Deque        DQ.add(7855642);        DQ.add(35658786);        DQ.add(5278367);        DQ.add(74381793);          // print Deque        System.out.println("Deque: " + DQ);          // print head        System.out.println("Deque's head: " + DQ.getLast());    }}

输出:

Deque: [7855642, 35658786, 5278367, 74381793]Deque's head: 74381793

程序5 。

// Java Program Demonstrate getLast()()// method of Deque when it is emptyimport java.util.*;  public class GFG {    public static void main(String[] args)        throws IllegalStateException    {          // create object of Deque        Deque<Integer> DQ            = new LinkedList<Integer>();          // Add numbers to end of Deque        DQ.add(7855642);        DQ.add(35658786);        DQ.add(5278367);        DQ.add(74381793);          // print Deque        System.out.println("Deque: " + DQ);          // print head        System.out.println("Deque's head: " + DQ.getLast());          DQ.clear();          // Deque is empty now hence exception        System.out.println("Deque's head: " + DQ.getLast());    }}

输出

Exception in thread "main" java.util.NoSuchElementException    at java.util.LinkedList.getLast(LinkedList.java:257)    at GFG.main(GFG.java:29)

参考资料: https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html#getLast-