Java ConcurrentSkipListMap ceilingKey()用法及代码示例

java.util.concurrent.ConcurrentSkipListMap的ceilingKey()方法是Java中的内置函数，它返回大于或等于给定键的最小键。如果没有这样的值，则返回null。没有键时，该方法将引发NullPointerException。

用法:

public K ceilingKey(K key)

参数：该函数接受单个强制性参数key。

返回值：该函数返回大于或等于key的最小键；如果没有这样的键，则返回null。

异常：该方法引发两种类型的异常：

ClassCastException：如果指定的键无法与Map中当前的键进行比较，并且
NullPointerException ：如果指定的键为null。

以下示例程序旨在说明上述方法：
示例1:

// Java program to demonstrate 
// ceilingkey method in java 
  
import java.util.concurrent.ConcurrentSkipListMap; 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        // Initializing the set 
        // using ConcurrentSkipListMap() 
        ConcurrentSkipListMap<Integer, Integer> 
            mpp = new ConcurrentSkipListMap<Integer, 
                                            Integer>(); 
  
        // Adding elements to this set 
        mpp.put(1, 1); 
        mpp.put(5, 2); 
        mpp.put(2, 7); 
  
        // Printing the ConcurrentSkipListMap 
        // Always in ascending order 
  
        System.out.println("Map: "
                           + mpp); 
  
        System.out.println("key greater than or equal 3: "
                           + mpp.ceilingKey(3)); 
  
        System.out.println("key greater than or equal 2: "
                           + mpp.ceilingKey(2)); 
    } 
}

输出：

Map: {1=1, 2=7, 5=2}
key greater than or equal 3: 5
key greater than or equal 2: 2

示例2:

// Java program to demonstrate 
// ceilingkey method in java 
import java.util.concurrent.ConcurrentSkipListMap; 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        // Initializing the set 
        // using ConcurrentSkipListMap() 
        ConcurrentSkipListMap<Integer, Integer> 
            mpp = new ConcurrentSkipListMap<Integer, 
                                            Integer>(); 
  
        // Adding elements to this set 
        mpp.put(11, 1); 
        mpp.put(51, 42); 
        mpp.put(92, 7); 
  
        // Printing the ConcurrentSkipListMap 
        // Always in ascending order 
  
        System.out.println("Map: "
                           + mpp); 
  
        System.out.println("key greater than or equal 11: "
                           + mpp.ceilingKey(11)); 
  
        System.out.println("key greater than or equal 51: "
                           + mpp.ceilingKey(51)); 
    } 
}

输出：

Map: {11=1, 51=42, 92=7}
key greater than or equal 11: 11
key greater than or equal 51: 51

参考： https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentSkipListMap.html#ceilingKey-K-

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注：本文由纯净天空筛选整理自Twinkl Bajaj大神的英文原创作品 ConcurrentSkipListMap ceilingKey() method in Java with Examples。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。