Java 中的 LinkedTransferQueue peek()方法
原文:https://www . geeksforgeeks . org/link edtransferqueue-peek-method-in-Java/
java . util . concurrent . linkedtransferqueue . peek()方法是 Java 中的内置函数，用于在队列非空的情况下返回队列头。
语法:
LinkedTransferQueue.peek()
参数:函数不接受任何参数。
返回值:如果队列非空，函数返回队列头，否则返回 null。
下面的程序说明了 LinkedTransferQueue.peek()方法:
程序 1:
// Java Program Demonstrate peek()
// method of LinkedTransferQueue
import java.util.concurrent.LinkedTransferQueue;
class LinkedTransferQueuePeekExample1 {
public static void main(String[] args)
{
// Initializing the queue
LinkedTransferQueue<Character> queue =
new LinkedTransferQueue<Character>();
// Adding elements to this queue
for (char ch = 'A'; ch <= 'Z'; ch++) {
queue.add(ch);
}
// Printing the head of the queue
System.out.println("The head of the queue is "
+ queue.peek());
// Printing all the elements of the queue
System.out.println("The elements in the queue :");
for (Character i : queue)
System.out.print(i + " ");
}
}
输出:
The head of the queue is A
The elements in the queue :
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
程序二:
// Java Program Demonstrate peek()
// method of LinkedTransferQueue
import java.util.concurrent.LinkedTransferQueue;
class LinkedTransferQueuePeekExample2 {
public static void main(String[] args)
{
// Initializing the queue
LinkedTransferQueue<Integer> queue =
new LinkedTransferQueue<Integer>();
// Adding elements to this queue
for (int i = 10; i <= 50; i += 10)
queue.add(i);
// Printing the head of the queue
System.out.println("The head of the queue is "
+ queue.peek());
// Printing all the elements of the queue
System.out.println("The elements in the queue :");
for (Integer i : queue)
System.out.print(i + " ");
}
}
输出:
The head of the queue is 10
The elements in the queue :
10 20 30 40 50
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