Java中的 ConcurrentSkipListSet pollLast() 方法
Java .util.concurrent.ConcurrentSkipListSet的pollLast()方法是Java中的一个内置函数,它返回检索并删除最后一个(最高)元素,如果此集合为空,则返回 null。
句法:
public E pollLast()
返回值:该函数返回检索并删除最后一个(最高)元素,如果此集合为空,则返回 null。
下面的程序说明了 ConcurrentSkipListSet.pollLast() 方法:
方案一:
// Java program to demonstrate pollLast()
// method of ConcurrentSkipListSet
import java.util.concurrent.*;
class ConcurrentSkipListSetpollLastExample1 {
public static void main(String[] args)
{
// Creating a set object
ConcurrentSkipListSet Lset = new ConcurrentSkipListSet();
// Adding elements to this set
for (int i = 10; i <= 50; i += 10)
Lset.add(i);
// Printing the content of the set
System.out.println("Contents of the set: " + Lset);
// Retrieving and removing Last element of the set
System.out.println("The Last element of the set: " + Lset.pollLast());
// Printing the content of the set after pollLast()
System.out.println("Contents of the set after pollLast: " + Lset);
}
}
输出:
Contents of the set: [10, 20, 30, 40, 50]
The Last element of the set: 50
Contents of the set after pollLast: [10, 20, 30, 40]
方案二:
// Java program to demonstrate pollLast()
// method of ConcurrentSkipListSet
import java.util.concurrent.*;
class ConcurrentSkipListSetpollLastExample2 {
public static void main(String[] args)
{
// Creating a set object
ConcurrentSkipListSet Lset = new ConcurrentSkipListSet();
// Printing the content of the set
System.out.println("Contents of the set: " + Lset);
// Retrieving and removing Last element of the set
System.out.println("The Last element of the set: " + Lset.pollLast());
}
}
输出:
Contents of the set: []
The Last element of the set: null
参考:
https://docs.oracle.com/javase/8/docs/api/java Java