Java ConcurrentSkipListMap用法及代碼示例

// Java Program to Demonstrate 
// ConcurrentSkipListMap 
  
import java.io.*; 
import java.util.*; 
import java.util.concurrent.*; 
  
class ConcurrentSkipListMapExample { 
    public static void main(String[] args) 
    { 
        // create an instance of ConcurrentSkipListMap 
        ConcurrentSkipListMap<String, String> cslm 
            = new ConcurrentSkipListMap<String, String>(); 
  
        // Add mappings using put method 
        cslm.put("3", "Geeks"); 
        cslm.put("2", "from"); 
        cslm.put("1", "Hi!"); 
        cslm.put("5", "Geeks"); 
        cslm.put("4", "for"); 
  
        // print to the console 
        System.out.println("Initial Map : " + cslm); 
  
        // print key-value pair whose key is greater than 2 
        System.out.println("ceilingEntry-2: "
                           + cslm.ceilingEntry("2")); 
  
        // get the descending key set 
        NavigableSet navigableSet = cslm.descendingKeySet(); 
  
        System.out.println("descendingKeySet: "); 
  
        // Iterate through the keySet 
        Iterator itr = navigableSet.iterator(); 
        while (itr.hasNext()) { 
            String s = (String)itr.next(); 
            System.out.println(s); 
        } 
  
        // print the first mapping 
        System.out.println("firstEntry: "
                           + cslm.firstEntry()); 
  
        // print the last mapping 
        System.out.println("lastEntry: "
                           + cslm.lastEntry()); 
  
        // remove the first mapping and print it 
        System.out.println("pollFirstEntry: "
                           + cslm.pollFirstEntry()); 
  
        // print the first mapping 
        System.out.println("now firstEntry: "
                           + cslm.firstEntry()); 
  
        // remove the last mapping and print it 
        System.out.println("pollLastEntry: "
                           + cslm.pollLastEntry()); 
  
        // print the last mapping 
        System.out.println("now lastEntry: "
                           + cslm.lastEntry()); 
    } 
}

// Java Program to demonstrate adding 
// mappings to a ConcurrentSkipListMap 
  
import java.util.concurrent.*; 
  
class AddingMappingsExample { 
    public static void main(String[] args) 
    { 
  
        // Initializing the map 
        ConcurrentSkipListMap<Integer, Integer> cslm 
            = new ConcurrentSkipListMap<Integer, Integer>(); 
  
        // Adding elements to this map 
        for (int i = 1; i <= 9; i++) 
            cslm.put(i, i); 
  
        // put() operation on the map 
        System.out.println("After put(): " + cslm); 
    } 
}

// Java Program Demonstrate removing 
// mappings from ConcurrentSkipListMap 
  
import java.util.concurrent.*; 
  
class RemovingMappingsExample { 
    public static void main(String[] args) 
    { 
  
        // Initializing the map 
        ConcurrentSkipListMap<Integer, Integer> cslm 
            = new ConcurrentSkipListMap<Integer, Integer>(); 
  
        // Adding elements to this map 
        for (int i = 1; i <= 6; i++) 
            cslm.put(i, i); 
  
        // remove() operation on the map 
        cslm.remove(5); 
  
        // print the modified map 
        System.out.println("After remove(): " + cslm); 
  
        // remove the first mapping and print it 
        System.out.println("pollFirstEntry: "
                           + cslm.pollFirstEntry()); 
  
        // remove the last mapping and print it 
        System.out.println("pollLastEntry: "
                           + cslm.pollLastEntry()); 
            
          // Print final map 
          System.out.println("map contents: " + cslm); 
    } 
}

// Java Program to demonstrate iterating 
// over ConcurrentSkipListMap 
  
import java.util.concurrent.*; 
import java.util.*; 
  
class IteratingExample { 
    public static void main(String[] args) 
    { 
        // create an instance of ConcurrentSkipListMap 
        ConcurrentSkipListMap<Integer, Integer> cslm 
            = new ConcurrentSkipListMap<>(); 
  
        // Add mappings using put method 
        for (int i = 0; i < 6; i++) { 
            cslm.put(i, i); 
        } 
  
        // Create an Iterator over the 
        // ConcurrentSkipListMap 
        Iterator<ConcurrentSkipListMap 
                     .Entry<Integer, Integer> > itr 
            = cslm.entrySet().iterator(); 
  
        // The hasNext() method is used to check if there is 
        // a next element The next() method is used to 
        // retrieve the next element 
        while (itr.hasNext()) { 
            ConcurrentSkipListMap 
                .Entry<Integer, Integer> entry 
                = itr.next(); 
            System.out.println("Key = " + entry.getKey() 
                               + ", Value = "
                               + entry.getValue()); 
        } 
    } 
}