Java Deque contains() 方法

2025 年 3 月 22 日 | 阅读需 2 分钟

Java Deque 接口的 contains() 方法在 deque 包含指定元素时返回 true。

指定者

Collection<E> 接口中的 contains

语法

参数

上述方法只有一个参数

a.) 元素 'o'，该元素已存在于 deque 中并被测试。

上述方法返回一个布尔值，即如果指定元素已存在于 deque 中，则为 true。

Throw

ClassCastException - 如果给定元素的类与 deque 不兼容。

NullPointerException - 如果指定元素为 null 且 deque 不允许 null 元素。

示例 1

import java.util.ArrayDeque;
import java.util.Deque;
public class JavaDequecontainsExample1 {
   public static void main(String[] args) {
	Deque<Float> deque = new ArrayDeque<>();
	System.out.println("The list of the elements is given as : ");
	deque.add(45f);
	deque.add(31f);
	deque.add(456f);
	deque.add(29f);
  System.out.println("The final result of the deque is given as : "+deque);
	 boolean b1 = deque.contains(45f);
	 if(b1==true)
	 {
		 System.out.println("The first element is in the list.");
	 }
	 else
	 {
		 System.out.println("The first element is not in the list.");
	 } 
	 boolean b2 = deque.contains(100f);
	 if(b2==true)
	 {
		 System.out.println("The second element is in the list.");
	 }
	 else
	 {
		 System.out.println("The second element is not in the list.");
	 }
   }
}

输出

The list of the elements is given as : 
The final result of the deque is given as : [45.0, 31.0, 456.0, 29.0]
The first element is in the list.
The second element is not in the list.

示例 2

import java.util.ArrayDeque;
import java.util.Deque;
public class JavaDequecontainsExample2 {
   public static void main(String[] args) {
	Deque<Character> deque = new ArrayDeque<>();
	System.out.println("The list of the elements is given as : ");
	deque.add('A');
	deque.add('J');
	deque.add('M');
	deque.add('O');
  System.out.println("The final result of the deque is given as : "+deque);
	 boolean b1 = deque.contains('Z');
	 if(b1==true)
	 {
		 System.out.println("The first element is in the list.");
	 }
	 else
	 {
		 System.out.println("The first element is not in the list.");
	 } 
	 boolean b2 = deque.contains('I');
	 if(b2==true)
	 {
		 System.out.println("The second element is in the list.");
	 }
	 else
	 {
		 System.out.println("The second element is not in the list.");
	 }
   }
}

输出

The list of the elements is given as : 
The final result of the deque is given as : [A, J, M, O]
The first element is not in the list.
The second element is not in the list.

示例 3

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Scanner;
public class JavaDequecontainsExample3 {
   public static void main(String[] args) {
	Scanner scanner = new Scanner(System.in);
	Deque<Character> deque = new ArrayDeque<>();
     System.out.println("The list of vowels is given as : ");
     deque.add('a'); 
     deque.add('e'); 
     deque.add('i'); 
     deque.add('o'); 
     deque.add('u'); 
     System.out.println(deque);
   Object b = null;
boolean val = deque.contains(b);
   if (val == true) {
	   System.out.println("The alphabet is a vowel.");
   }
   else {
	   System.out.println("The alphabet is not a vowel.");
   }
   
   
   }
}

输出

The list of vowels is given as : 
[a, e, i, o, u]
The alphabet is not a vowel.

下一主题Java Deque

Java Deque contains() 方法

指定者

语法

参数

返回

Throw

示例 1

示例 2

示例 3

联系信息

关注我们

教程

面试题

在线编译器

Python

Java

.Net Framework

AI, ML and Data Science

Cloud Technology

B.Tech and MCA

Web Technology

PHP

Software Testing

Technical Interview

Java Interview

Python

Web Interview

Database Interview

B.Tech / MCA

Important Interview

Software Testing Interview

Company Interviews

Online Compilers

Multiple Choice Questions

Java String 方法

Java 数组类

Java Math 方法

ArrayList 方法

Java List 方法

Java 线程方法

Java Date 类

Java Collection 方法

Java ListIterator 类

Java NIO 教程

HttpURLConnection

Java Deque

Java HttpCookie 类

Java URL 类

Java Vector 类

Java Socket 类

Java Executors

Java Integer 类

Java IdentityHashMap

Java ArrayBlockingQueue

Java Timestamp

Java Spliterator

Java Bitset

Java Instant

Java Compiler 类

Java AtomicInteger 类

Java AtomicLong 方法

Java Authenticator

Java BigDecimal 类

Big Integer 类

Java Boolean 类

Java Byte Class

Java Class

Java Collections 类

CopyOnWriteArrayList

LinkedBlockingDeque

Java Long 类

LinkedTransferQueue

Java List

Java MulticastSocket

Java Number 类

Java Phaser 类

Java Deque contains() 方法

指定者

语法

参数

返回

Throw

示例 1

示例 2

示例 3

相关帖子

getLast()

push()

getFirst()

poll()

Java Deque

peekFirst()

removeLastOccurrence()

add()