Java中的 ConcurrentSkipListSet Higher() 方法

Java .util.concurrent.ConcurrentSkipListSet的higher(E e)方法是Java中的一个内置函数，它返回此集合中严格大于给定元素的最小元素，如果没有这样的元素，则返回null。

句法：

public E higher(E e)

参数：该函数接受单个参数e即要匹配的值

返回值：该函数返回大于 e 的最小元素，如果没有这样的元素，则返回 null。

异常：该函数抛出以下异常：

ClassCastException – 如果指定的元素无法与集合中当前的元素进行比较。

NullPointerException – 如果指定元素为 null

下面的程序说明了 ConcurrentSkipListSet.higher(E e) 方法：

方案一：

// Java program to demonstrate higher()
// method of ConcurrentSkipListSet
  
import java.util.concurrent.*;
  
class ConcurrentSkipListSetHigherExample1 {
    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);
  
        // Finding higher of 20 in the set
        System.out.println("The higher of 20 in the set: "
                           + Lset.higher(20));
  
        // Finding higher of 39 in the set
        System.out.println("The higher of 39 in the set: "
                           + Lset.higher(39));
  
        // Finding higher of 50 in the set
        System.out.println("The higher of 50 in the set: "
                           + Lset.higher(50));
    }
}

输出：

The higher of 20 in the set: 30
The higher of 39 in the set: 40
The higher of 50 in the set: null

程序 2：在 Higher() 中显示 NullPointerException 的程序。

// Java program to demonstrate higher()
// method of ConcurrentSkipListSet
  
import java.util.concurrent.*;
  
class ConcurrentSkipListSetHigherExample1 {
    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);
  
        try {
            // Trying to find higher of "null" in the set
            System.out.println("The higher of null in the set: "
                               + Lset.higher(null));
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出：

Exception: java.lang.NullPointerException

参考：
https://docs.oracle.com/javase/8/docs/api/java Java