java peek方法

ArrayDeque类peek()方法 (ArrayDeque Class peek() method)

• peek() Method is available in java.lang package.

  peek()方法在java.lang包中可用。

• peek() Method is used to return the head element of the queue denoted by this deque but without removing the element.

  peek()方法用于返回此双端队列表示的队列的头元素，但不删除该元素。

• peek() Method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  peek()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• peek() Method does not throw an exception at the time retrieving the head element of this deque.

  peek()方法在检索此双端队列的head元素时不会引发异常。

Syntax:

句法：

    public T peek();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

Return value:

返回值：

The return type of the method is T, it returns the head element denoted by this deque otherwise it returns null when this deque is "blank".

方法的返回类型为T ，它返回此双端队列表示的head元素，否则当此双端队列为“空白”时返回null。

Example:

例：

// Java program to demonstrate the example
// of T peek() method of ArrayDeque
import java.util.*;
public class PeekOfArrayDeque {public static void main(String[] args) {// Creating an ArrayDeque with initial capacity of
// storing elements
Deque < String > d_queue = new ArrayDeque < String > (10);
// By using add() method to add elements
// in ArrayDeque
d_queue.add("C");
d_queue.add("C++");
d_queue.add("Java");
d_queue.add("Php");
d_queue.add("DotNet");
// Display Deque Elements
System.out.println("d_queue before peek(): ");
System.out.println("ArrayDeque Elements = " + d_queue);
System.out.println();
// By using peek() method to return the
// element at the first position in ArrayDeque
String ele = d_queue.peek();
// Display Returned Elements
System.out.println("d_queue.peek() : " + ele);
}
}

Output

输出量

d_queue before peek():
ArrayDeque Elements = [C, C++, Java, Php, DotNet]d_queue.peek() : C

翻译自: https://www.includehelp.com/java/arraydeque-peek-method-with-example.aspx

java peek方法