java.util.TreeMap.lastKey()用于检索Map中存在的最后一个或最高键。

用法:

tree_map.lastKey()

参数：该方法不带任何参数。

返回值：该方法返回映射中存在的最后一个键。

异常：如果映射为空，则该方法将引发NoSuchElementException。

以下程序说明了java.util.TreeMap.lastKey()方法的用法：

示例1:

// Java code to illustrate the lastKey() method

import java.util.*;

public class Tree_Map_Demo {

public static void main(String[] args)

{

// Creating an empty TreeMap

TreeMap tree_map = new TreeMap();

// Mapping string values to int keys

tree_map.put(10, "Geeks");

tree_map.put(15, "4");

tree_map.put(20, "Geeks");

tree_map.put(25, "Welcomes");

tree_map.put(30, "You");

// Displaying the TreeMap

System.out.println("The Mappings are: " + tree_map);

// Displaying the lastKey of the map

System.out.println("The last key is " + tree_map.lastKey());

}

}

输出：

The Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}

The last key is 30

示例2:

// Java code to illustrate the lastKey() method

import java.util.*;

public class Tree_Map_Demo {

public static void main(String[] args)

{

// Creating an empty TreeMap

TreeMap tree_map = new TreeMap();

// Mapping int values to string keys

tree_map.put("Geeks", 10);

tree_map.put("4", 15);

tree_map.put("Geeks", 20);

tree_map.put("Welcomes", 25);

tree_map.put("You", 30);

// Displaying the TreeMap

System.out.println("The Mappings are: " + tree_map);

// Displaying the lastKey of the map

System.out.println("The last key is " + tree_map.lastKey());

}

}

输出：

The Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}

The last key is You