Java ConcurrentSkipListSet floor()用法及代码示例

java.util.concurrent.ConcurrentSkipListSet的floor()方法是Java中的一个内置函数，该函数返回该集合中小于或等于给定元素的最大元素；如果没有此类元素，则返回null。

用法:

ConcurrentSkipListSet.floor(E e)

参数：该函数接受单个参数，即要匹配的值。

返回值：该函数返回小于或等于e的最大元素，如果没有这样的元素，则返回null。

异常：该函数引发以下异常：

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

以下示例程序旨在说明ConcurrentSkipListSet.floor()方法：

示例1:

// Java program to demonstrate floor() 
// method of ConcurrentSkipListSet 
  
import java.util.concurrent.*; 
  
class ConcurrentSkipListSetFloorExample1 { 
    public static void main(String[] args) 
    { 
        // Creating a set object 
        ConcurrentSkipListSet<Integer> 
            Lset = new ConcurrentSkipListSet<Integer>(); 
  
        // Adding elements to this set 
        for (int i = 10; i <= 50; i += 10) 
            Lset.add(i); 
  
        // Finding floor of 20 in the set 
        System.out.println("The floor of 20 in the set "
                           + Lset.floor(20)); 
  
        // Finding floor of 39 in the set 
        System.out.println("The floor of 39 in the set "
                           + Lset.floor(39)); 
  
        // Finding floor of 9 in the set 
        System.out.println("The floor of 10 in the set "
                           + Lset.floor(9)); 
    } 
}

输出：

The floor of 20 in the set 20
The floor of 39 in the set 30
The floor of 10 in the set null

示例2:在floor()中显示NullPointerException的程序。

// Java program to demonstrate floor() 
// method of ConcurrentSkipListSet 
  
import java.util.concurrent.*; 
  
class ConcurrentSkipListSetFloorExample2 { 
    public static void main(String[] args) 
    { 
        // Creating a set object 
        ConcurrentSkipListSet<Integer> 
            Lset = new ConcurrentSkipListSet<Integer>(); 
  
        // Adding elements to this set 
        for (int i = 10; i <= 50; i += 10) 
            Lset.add(i); 
  
        // Trying to find the floor of null 
        try { 
            System.out.println("The floor of null in the set "
                               + Lset.floor(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/util/concurrent/ConcurrentSkipListSet.html#floor-E-

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注：本文由纯净天空筛选整理自rupesh_rao大神的英文原创作品 ConcurrentSkipListSet floor() method in Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。