这个 包含（E） 方法 Deque接口 检查Deque容器中是否存在元素e。如果Deque包含元素的一个匹配项，则返回true，否则返回false。
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语法：
boolean contains(Object o)
参数： 该方法接受一个强制参数o，如果它是否存在于Deque中，则该参数是需要测试的元素。
返回值： 该方法返回 符合事实的 如果元素出现在Deque中，则返回 错误的
例外情况： 该函数引发两个异常，如下所示：
- 类别例外 –如果指定元素的类型与本文件不兼容。这是可选的。
- 空指针异常 –如果指定的元素为空，并且此数据不允许空元素（可选）。这是可选的。
下面的程序演示了Java中的contains（）方法：
项目1： 借助于 链表 .
// Java code to illustrate contains() // method of Deque in Java import java.util.*; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<String> de_que = new LinkedList<String>(); // Use add() method to add elements into the Queue de_que.add( "Welcome" ); de_que.add( "To" ); de_que.add( "Geeks" ); de_que.add( "4" ); de_que.add( "Geeks" ); // Displaying the Deque System.out.println( "Deque: " + de_que); // Check for "Geeks" in the deque System.out.println( "Does the deque contains 'Geeks'? " + de_que.contains( "Geeks" )); // Check for "4" in the deque System.out.println( "Does the deque contains '4'? " + de_que.contains( "4" )); // Check if the deque contains "No" System.out.println( "Does the deque contains 'No'? " + de_que.contains( "No" )); } } |
输出：
Deque: [Welcome, To, Geeks, 4, Geeks] Does the deque contains 'Geeks'? true Does the deque contains '4'? true Does the deque contains 'No'? false
项目2：
// Java code to illustrate contains() // method of Deque in Java import java.util.*; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<Integer> de_que = new LinkedList<Integer>(); // Use add() method to add elements into the Queue de_que.add( 10 ); de_que.add( 15 ); de_que.add( 30 ); de_que.add( 20 ); de_que.add( 5 ); // Displaying the Deque System.out.println( "Deque: " + de_que); // Check for '15' in the Deque System.out.println( "Does the Deque contains '15'? " + de_que.contains( 15 )); // Check for '2' in the Deque System.out.println( "Does the Deque contains '2'? " + de_que.contains( 2 )); // Check if the Deque contains '10' System.out.println( "Does the Deque contains '10'? " + de_que.contains( 10 )); } } |
输出：
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
方案3： 借助于 ArrayDeque .
// Java code to illustrate contains() // method of Deque in Java import java.util.*; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<Integer> de_que = new ArrayDeque<Integer>(); // Use add() method to add elements into the Queue de_que.add( 10 ); de_que.add( 15 ); de_que.add( 30 ); de_que.add( 20 ); de_que.add( 5 ); // Displaying the Deque System.out.println( "Deque: " + de_que); // Check for '15' in the Deque System.out.println( "Does the Deque contains '15'? " + de_que.contains( 15 )); // Check for '2' in the Deque System.out.println( "Does the Deque contains '2'? " + de_que.contains( 2 )); // Check if the Deque contains '10' System.out.println( "Does the Deque contains '10'? " + de_que.contains( 10 )); } } |
输出：
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
方案4： 借助于 ConcurrentLinkedEque .
// Java code to illustrate contains() // method of Deque in Java import java.util.*; import java.util.concurrent.ConcurrentLinkedDeque; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<Integer> de_que = new ConcurrentLinkedDeque<Integer>(); // Use add() method to add elements into the Queue de_que.add( 10 ); de_que.add( 15 ); de_que.add( 30 ); de_que.add( 20 ); de_que.add( 5 ); // Displaying the Deque System.out.println( "Deque: " + de_que); // Check for '15' in the Deque System.out.println( "Does the Deque contains '15'? " + de_que.contains( 15 )); // Check for '2' in the Deque System.out.println( "Does the Deque contains '2'? " + de_que.contains( 2 )); // Check if the Deque contains '10' System.out.println( "Does the Deque contains '10'? " + de_que.contains( 10 )); } } |
输出：
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
方案5： 借助于 LinkedBlockingDeque .
// Java code to illustrate contains() // method of Deque in Java import java.util.*; import java.util.concurrent.LinkedBlockingDeque; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<Integer> de_que = new LinkedBlockingDeque<Integer>(); // Use add() method to add elements into the Queue de_que.add( 10 ); de_que.add( 15 ); de_que.add( 30 ); de_que.add( 20 ); de_que.add( 5 ); // Displaying the Deque System.out.println( "Deque: " + de_que); // Check for '15' in the Deque System.out.println( "Does the Deque contains '15'? " + de_que.contains( 15 )); // Check for '2' in the Deque System.out.println( "Does the Deque contains '2'? " + de_que.contains( 2 )); // Check if the Deque contains '10' System.out.println( "Does the Deque contains '10'? " + de_que.contains( 10 )); } } |
输出：
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
注： 异常依赖于编译器，因此无法在程序中显示。 参考： https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html#contains-爪哇。lang.反对-
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