Java ConcurrentSkipListSet last()方法

java.util.concurrent.ConcurrentSkipListSet 的 last() 方法是Java中的一个内置函数，用于返回当前该集合中最后一个（最高）元素。

语法

public E last()

返回值： 该函数返回当前在这个集合中的最后（最高）元素。

异常： 如果这个集合是空的，该函数会抛出NoSuchElementException。

下面的程序说明了ConcurrentSkipListSet.last()方法。

程序1 :

// Java program to demonstrate last()
// method of ConcurrentSkipListSet
  
import java.util.concurrent.ConcurrentSkipListSet;
  
class ConcurrentSkipListSetLastExample1 {
    public static void main(String[] args)
    {
  
        // Initializing the set
        ConcurrentSkipListSet<Integer>
            set = new ConcurrentSkipListSet<Integer>();
  
        // Adding elements to this set
        set.add(78);
        set.add(64);
        set.add(12);
        set.add(45);
        set.add(8);
  
        // Printing the highest element of the set
        System.out.println("The highest element of the set: "
                           + set.last());
    }
}

输出:

The highest element of the set: 78

程序2： 在last()中显示NoSuchElementException的程序。

// Java program to demonstrate last()
// method of ConcurrentSkipListSet
  
import java.util.concurrent.ConcurrentSkipListSet;
  
class ConcurrentSkipListSetLastExample1 {
    public static void main(String[] args)
    {
  
        // Initializing the set
        ConcurrentSkipListSet<Integer>
            set = new ConcurrentSkipListSet<Integer>();
        try {
            // Printing the highest element of the set
            System.out.println("The highest element of the set: "
                               + set.last());
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出:

Exception: java.util.NoSuchElementException

参考资料: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentSkipListSet.html#last-