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Java Deque add()用法及代码示例


如果有空间,则双端队列接口的add(E e)方法会将参数中传递的元素插入到双端队列的末尾。如果Deque受容量限制并且没有剩余空间可插入,则它将返回IllegalStateException。成功插入后,该函数返回true。

用法:

boolean add(E e)

参数:此方法接受强制性参数e,该参数是要在双端队列的末尾插入的元素。

返回:成功插入后,此方法返回true。

异常:该函数引发四个异常,如下所述:



  • ClassCastException:当要输入的元素的类阻止将其添加到此容器中时:
  • IllegalStateException:当容器的容量已满并且已插入时。
  • IllegalArgumentException:当元素的某些属性阻止将其添加到双端队列时。
  • NullPointerException :当要插入的元素作为null传递并且Deque的接口不允许使用null元素时:

以下示例程序旨在说明Deque的add()方法:

程序1:借助LinkedList。

Java

// Java Program Demonstrate add()
// method of Deque
import java.util.*;
 
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
 
        // create object of De1ue
        Deque<Integer> DQ
            = new LinkedList<Integer>();
 
        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);
 
        // before removing print Deque
        System.out.println("Deque:" + DQ);
    }
}
输出:
Deque:[7855642, 35658786, 5278367, 74381793]




程序2:借助ArrayDeque。

Java

// Java Program Demonstrate add()
// method of Deque
import java.util.*;
 
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
 
        // create object of De1ue
        Deque<Integer> DQ
            = new ArrayDeque<Integer>();
 
        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);
 
        // before removing print Deque
        System.out.println("Deque:" + DQ);
    }
}
输出:
Deque:[7855642, 35658786, 5278367, 74381793]




程序3:借助ConcurrentLinkedDeque。

Java

// Java Program Demonstrate add()
// method of Deque
import java.util.*;
import java.util.concurrent.ConcurrentLinkedDeque;
 
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
 
        // create object of De1ue
        Deque<Integer> DQ
            = new ConcurrentLinkedDeque<Integer>();
 
        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);
 
        // before removing print Deque
        System.out.println("Deque:" + DQ);
    }
}
输出:
Deque:[7855642, 35658786, 5278367, 74381793]




程序4:借助LinkedBlockingDeque。



Java

// Java Program Demonstrate add()
// method of Deque
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;
 
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
 
        // create object of De1ue
        Deque<Integer> DQ
            = new LinkedBlockingDeque<Integer>();
 
        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);
 
        // before removing print Deque
        System.out.println("Deque:" + DQ);
    }
}
输出:
Deque:[7855642, 35658786, 5278367, 74381793]




以下示例程序旨在说明add()方法引发的异常:

程序5:显示NullPointerException。

Java

/// Java Program Demonstrate add()
// method of DeQue when Null is passed
import 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);
        // when null is inserted
        DQ.add(null);
 
        // before removing print DeQue
        System.out.println("DeQue:" + DQ);
    }
}

输出:

Exception in thread "main" java.lang.NullPointerException
    at java.util.concurrent.LinkedBlockingDeque.offerLast(LinkedBlockingDeque.java:357)
    at java.util.concurrent.LinkedBlockingDeque.addLast(LinkedBlockingDeque.java:334)
    at java.util.concurrent.LinkedBlockingDeque.add(LinkedBlockingDeque.java:633)
    at GFG.main(GFG.java:20)

程序6:显示IllegalStateException。

Java

// Java Program Demonstrate add()
// method of Deque when capacity is full
import 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>(3);
 
        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
 
        // when capacity is full
        DQ.add(10);
 
        // before removing print Deque
        System.out.println("Deque:" + DQ);
    }
}

输出:

Exception in thread "main" java.lang.IllegalStateException:Deque full
    at java.util.concurrent.LinkedBlockingDeque.addLast(LinkedBlockingDeque.java:335)
    at java.util.concurrent.LinkedBlockingDeque.add(LinkedBlockingDeque.java:633)
    at GFG.main(GFG.java:21)

注意:其他两个异常是内部的,它们是由编译器引起的,因此无法在编译器中显示。

参考: https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html#add-E-

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注:本文由纯净天空筛选整理自gopaldave大神的英文原创作品 Deque add() method in Java。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。