Java NavigableMap higherKey()用法及代碼示例

NavigableMap接口的higherKey()方法用於返回嚴格大於給定鍵的最小鍵；如果沒有這樣的鍵，則返回null。

用法:

public K higherKey(K key)

參數：該方法將 key k作為參數。

返回值：此方法返回大於key的最小鍵；如果沒有這樣的鍵，則返回null。

異常：如果指定鍵為null且此映射使用自然順序，或者其比較器不允許使用null鍵，則此方法將引發NullPointerException。

下麵是說明higherKey()方法的示例：

示例1:

// Java program to demonstrate 
// higherKey() method 
// for <Integer, String> 
  
import java.util.*; 
  
public class GFG1 { 
    public static void main(String[] args) throws Exception 
    { 
        try { 
  
            // Creating object of NavigableMap 
            NavigableMap<Integer, String> 
                navmap = new TreeMap<Integer, String>(); 
  
            // Populating the map 
            navmap.put(1, "One"); 
            navmap.put(2, "Two"); 
            navmap.put(3, "Three"); 
            navmap.put(4, "Four"); 
            navmap.put(5, "Five"); 
  
            // Pritnig the TreeMap 
            System.out.println("NavigableMap: " + navmap); 
  
            // Getting higher key value for 3 
            // using higherKey() method 
            int value = navmap.higherKey(3); 
  
            // Printing the value 
            System.out.println("The higherKey value "
                               + " for 3: " + value); 
        } 
  
        catch (NullPointerException e) { 
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

輸出：

NavigableMap: {1=One, 2=Two, 3=Three, 4=Four, 5=Five}
The higherKey value  for 3: 4

示例2:對於NullPointerException

// Java program to demonstrate 
// higherKey() method 
// for NullPointerException 
  
import java.util.*; 
  
public class GFG1 { 
    public static void main(String[] args) throws Exception 
    { 
        try { 
  
            // Creating object of TreeMap<Integer, String> 
            NavigableMap<Integer, String> 
                navmap = new TreeMap<Integer, String>(); 
  
            // Populating tree map 
            navmap.put(1, "One"); 
            navmap.put(2, "Two"); 
            navmap.put(3, "Three"); 
            navmap.put(4, "Four"); 
            navmap.put(5, "Five"); 
  
            // Printnig the NavigableMap 
            System.out.println("TreeMap: " + navmap); 
  
            // Getting higher key value for null 
            // Using higherKey() method 
            System.out.println("Trying to get higherKey"
                               + " value for null"); 
  
            int value = navmap.higherKey(null); 
  
            // Printing the value 
            System.out.println("Value is: " + value); 
        } 
  
        catch (NullPointerException e) { 
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

輸出：

TreeMap: {1=One, 2=Two, 3=Three, 4=Four, 5=Five}
Trying to get higherKey value for null
Exception thrown : java.lang.NullPointerException

相關用法

注：本文由純淨天空篩選整理自Chinmoy Lenka大神的英文原創作品 NavigableMap higherKey() Method in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。