Java中的 TreeMap containsValue() 方法及示例

在Java中，TreeMap 类的containsValue() 方法用于检查特定值是否被 TreeMap 中的任何键映射。它将值作为参数，如果该值由映射中的任何键映射，则返回 True。

--> java.util Package 
    --> TreeMap class
        --> containsValue() Method  

句法：

Tree_Map.containsValue(Object Value)

参数： Object类型的值，指的是映射应该被映射中的任何键检查的值。 （只有一个参数）

返回类型：布尔值，如果检测到值的映射则为 true，否则为 false。

Note: In java, while returning boolean values are returned as true false only not as 0 and 1 as it is not allowed so do will throw error ar compilation.

示例 1：将字符串值映射到整数键。

Java

// Java Program to Illustrate containsValue() Method
// of TreeMap class
 
// Importing required classes
import java.util.*;
 
// Main class
public class GFG {
 
    // main driver method
    public static void main(String[] args)
    {
        // Creating an empty TreeMap by
        // declaring object of integer and string pairs
        TreeMap tree_map
            = new TreeMap();
 
        // Mapping string values to int keys
        // using put() method
        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");
 
        // Printing the elements of TreeMap
        System.out.println("Initial Mappings are: "
                           + tree_map);
 
        // Checking for custom value in map
        // using containsValue() method
 
        // Say for the Value 'Geeks'
        System.out.println(
            "Is the value 'Geeks' present? "
            + tree_map.containsValue("Geeks"));
 
        // Checking for the Value 'World'
        System.out.println(
            "Is the value 'World' present? "
            + tree_map.containsValue("World"));
    }
}

输出

Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
Is the value 'Geeks' present? true
Is the value 'World' present? false

示例 2：将整数值映射到字符串键。

Java

// Java Program  to illustrate containsValue() Method
// of TreeMap class
 
// Importing required classes
import java.util.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating an empty TreeMap by
        // declaring object of string, integer pairs
        TreeMap tree_map
            = new TreeMap();
 
        // Mapping int values to string keys
        // using put() method
        tree_map.put("Geeks", 10);
        tree_map.put("4", 15);
        tree_map.put("Geeks", 20);
        tree_map.put("Welcomes", 25);
        hastree_map_map.put("You", 30);
 
        // Printing the elements of TreeMap
        System.out.println("Initial Mappings are: "
                           + tree_map);
 
        // Checking for the Value '10'
        // using containsValue() method
        System.out.println("Is the value '10' present? "
                           + tree_map.containsValue(10));
 
        // Checking for the Value '30'
        System.out.println("Is the value '30' present? "
                           + tree_map.containsValue(30));
 
        // Checking for the Value '40'
        System.out.println("Is the value '40' present? "
                           + tree_map.containsValue(40));
    }
}

输出：

Note: Similarly the same operation can be performed with any type of Mappings with variation and combination of different data types.