Java 中的 TreeMap lastKey()方法
原文:https://www . geesforgeks . org/tree map-last key-method-in-Java/
java.util.TreeMap.lastKey()用于检索地图中最后或最高的键。
语法:
tree_map.lastKey()
参数:该方法不取任何参数。
返回值:该方法返回地图中出现的最后一个键。
异常:如果地图为空，该方法抛出nosucheelementexception。
下面的程序说明了 java.util.TreeMap.lastKey()方法的工作: 程序 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<Integer, String> tree_map = new TreeMap<Integer, String>();
// 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());
}
}
Output:
The Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
The last key is 30
程序 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<String, Integer> tree_map = new TreeMap<String, Integer>();
// 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());
}
}
Output:
The Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
The last key is You
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