Java ConcurrentSkipListSet与实例

Java中的 ConcurrentSkipListSet 类是Java集合框架的一部分，实现了 集合接口 和 AbstractSet类。 它为Java中的NavigableSet提供了一个可扩展和并发的版本。ConcurrentSkipListSet的实现是基于 ConcurrentSkipListMap的。 ConcurrentSkipListSet中的元素默认是按自然顺序排序的，或者按集合创建时提供的比较器排序，这取决于使用哪个构造函数。

因为它实现了 **SortedSet **和 **NavigableSet **，所以它与TreeSet类似，但增加了一个并发的特性。由于它是线程安全的，它可以被多个线程并发使用，而TreeSet不是线程安全的。

类的层次结构

声明

public class ConcurrentSkipListSet<E>
    extends AbstractSet<E>
        implements NavigableSet<E>, Cloneable, Serializable

Where **E** is the type of elements maintained by this collection

ConcurrentSkipListSet的一些要点

• 它实现了 Serializable , Cloneable , **Iterable **, **Collection **, NavigableSet, Set, SortedSet接口。
• 它不允许空元素，因为空参数和返回值不能与没有元素的情况可靠地区分开。
• 它的实现为包含、添加和删除操作及其变体提供了平均对数（n）的时间成本。
• 它是线程安全的。
• 当需要对集合进行并发修改时，它应该比实现Set接口更受欢迎。

构造函数

1.ConcurrentSkipListSet() : 这个构造函数用来构造一个空集合。

ConcurrentSkipListSet<E> set = new ConcurrentSkipListSet<E>()

**2.ConcurrentSkipListSet(Collection c) **: 这个构造函数用来构造一个集合，集合中的元素作为参数传递。

ConcurrentSkipListSet<E> set = new ConcurrentSkipListSet<E>(Collection<E> c)

**3.ConcurrentSkipListSet(Comparator comparator) **: 这个构造函数用来构造一个新的空集合，根据指定的比较器对其元素进行排序。

ConcurrentSkipListSet<E> set = new ConcurrentSkipListSet<E>(Comparator<E> comparator)

**4.ConcurrentSkipListSet(SortedSet s) **: 这个构造函数用来构造一个新的集合，包含相同的元素，并使用与指定的排序集合相同的排序。

ConcurrentSkipListSet<E> set = new ConcurrentSkipListSet<E>（SortedSet<E> s）

例1 :

// Java program to demonstrate ConcurrentSkipListSet
  
import java.util.*;
import java.util.concurrent.ConcurrentSkipListSet;
  
class ConcurrentSkipListSetLastExample1 {
    public static void main(String[] args)
    {
  
        // Initializing the set using
        // ConcurrentSkipListSet()
        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 ConcurrentSkipListSet
        System.out.println("ConcurrentSkipListSet: " + set);
  
        // Initializing the set using
        // ConcurrentSkipListSet(Collection)
        ConcurrentSkipListSet<Integer> set1
            = new ConcurrentSkipListSet<Integer>(set);
  
        // Printing the ConcurrentSkipListSet1
        System.out.println("ConcurrentSkipListSet1: "
                           + set1);
  
        // Initializing the set using
        // ConcurrentSkipListSet()
        ConcurrentSkipListSet<String> set2
            = new ConcurrentSkipListSet<>();
  
        // Adding elements to this set
        set2.add("Apple");
        set2.add("Lemon");
        set2.add("Banana");
        set2.add("Apple");
  
        // creating an iterator
        Iterator<String> itr = set2.iterator();
  
        System.out.print("Fruits Set: ");
        while (itr.hasNext()) {
            System.out.print(itr.next() + " ");
        }
    }
}

输出

ConcurrentSkipListSet: [8, 12, 45, 64, 78]
ConcurrentSkipListSet1: [8, 12, 45, 64, 78]
Fruits Set: Apple Banana Lemon 

例2 :

// Java program to demonstrate ConcurrentSkipListSet
  
import java.util.concurrent.ConcurrentSkipListSet;
  
class ConcurrentSkipListSetLastExample1 {
    
    public static void main(String[] args)
    {
  
        // Initializing the set using ConcurrentSkipListSet()
        ConcurrentSkipListSet<Integer>
            set = new ConcurrentSkipListSet<Integer>();
  
        // Adding elements to this set
        // using add() method
        set.add(78);
        set.add(64);
        set.add(12);
        set.add(45);
        set.add(8);
  
        // Printing the ConcurrentSkipListSet
        System.out.println("ConcurrentSkipListSet: "
                           + set);
  
        // Printing the highest element of the set
        // using last() method
        System.out.println("The highest element of the set: "
                           + set.last());
  
        // Retrieving and removing first element of the set
        System.out.println("The first element of the set: "
                           + set.pollFirst());
  
        // Checks if 9 is present in the set
        // using contains() method
        if (set.contains(9))
            System.out.println("9 is present in the set.");
        else
            System.out.println("9 is not present in the set.");
  
        // Printing the size of the set
        // using size() method
        System.out.println("Number of elements in the set = "
                           + set.size());
    }
}

输出

ConcurrentSkipListSet: [8, 12, 45, 64, 78]
The highest element of the set: 78
The first element of the set: 8
9 is not present in the set.
Number of elements in the set = 4

ConcurrentSkipListSet的方法

从java.util.Collection接口继承的方法

从java.lang.Iterable接口继承的方法