📜  Java中的 NavigableMap highKey() 方法

📅  最后修改于: 2022-05-13 01:54:51.005000             🧑  作者: Mango

Java中的 NavigableMap highKey() 方法

NavigableMap 接口的HigherKey()方法用于返回严格大于给定键的最小键,如果没有这样的键,则返回 null。

句法:

public K higherKey(K key)

参数:此方法以键 k作为参数。

返回值:此方法返回大于 key 的最小 key,如果没有这样的 key,则返回null

异常:如果指定的键为空并且此映射使用自然排序,或者其比较器不允许空键,则此方法抛出NullPointerException

下面是说明higherKey()方法的示例:

示例 1:

Java
// Java program to demonstrate
// higherKey() method
// for 
 
import java.util.*;
 
public class GFG1 {
    public static void main(String[] args) throws Exception
    {
        try {
 
            // Creating object of NavigableMap
            NavigableMap
                navmap = new TreeMap();
 
            // Populating the map
            navmap.put(1, "One");
            navmap.put(2, "Two");
            navmap.put(3, "Three");
            navmap.put(4, "Four");
            navmap.put(5, "Five");
 
            // Printing 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);
        }
    }
}


Java
// 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
            NavigableMap
                navmap = new TreeMap();
 
            // Populating tree map
            navmap.put(1, "One");
            navmap.put(2, "Two");
            navmap.put(3, "Three");
            navmap.put(4, "Four");
            navmap.put(5, "Five");
 
            // Printing 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);
        }
    }
}


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

示例 2:对于NullPointerException

Java

// 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
            NavigableMap
                navmap = new TreeMap();
 
            // Populating tree map
            navmap.put(1, "One");
            navmap.put(2, "Two");
            navmap.put(3, "Three");
            navmap.put(4, "Four");
            navmap.put(5, "Five");
 
            // Printing 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);
        }
    }
}
输出:
TreeMap: {1=One, 2=Two, 3=Three, 4=Four, 5=Five}
Trying to get higherKey value for null
Exception thrown : java.lang.NullPointerException