Java中Hashtable类的java.util.Hashtable.containsValue()方法用于检查特定值是由Hashtable中的单个键还是多个键映射。它将Value作为参数,如果该值由表中的任何键映射,则返回True。

句法:

Hash_Table.containsValue(Object Value)

参数:该方法只接受一个参数 Object类型,并引用其映射应该由表中的任何键检查的值。

返回值:如果值映射到Hashtable中的任何键,则该方法返回boolean true,否则返回false。

下面的程序用于说明java.util.Hashtable.containsValue()的工作方法

程序1:

// Java code to illustrate the containsValue() method
import java.util.*;
 
public class Hash_Table_Demo {
    public static void main(String[] args)
    {
 
        // Creating an empty Hashtable
        Hashtable<Integer, String> hash_table = 
        new Hashtable<Integer, String>();
 
        // Putting values in the table
        hash_table.put(10, "Geeks");
        hash_table.put(15, "4");
        hash_table.put(20, "Geeks");
        hash_table.put(25, "Welcomes");
        hash_table.put(30, "You");
 
        // Displaying the Hashtable
        System.out.println("Initial Table is: " + hash_table); 
 
        // Checking for the Value 'Geeks'
        System.out.println("Is the value 'Geeks' present? " + 
        hash_table.containsValue("Geeks"));
 
        // Checking for the Value 'World'
        System.out.println("Is the value 'World' present? " + 
        hash_table.containsValue("World"));
    }
}

输出:

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

程序2:

// Java code to illustrate the containsValue() method
import java.util.*;
 
public class Hash_Table_Demo {
    public static void main(String[] args)
    {
 
        // Creating an empty Hashtable
        Hashtable<String, Integer> hash_table = 
        new Hashtable<String, Integer>();
 
        // Putting values in the table
        hash_table.put("Geeks", 10);
        hash_table.put("4", 15);
        hash_table.put("Geeks", 20);
        hash_table.put("Welcomes", 25);
        hash_table.put("You", 30);
 
        // Displaying the Hashtable
        System.out.println("Initial Table is: " + hash_table); 
 
        // Checking for the Value '10'
        System.out.println("Is the value '10' present? " + 
        hash_table.containsValue(10));
 
        // Checking for the Value '30'
        System.out.println("Is the value '30' present? " + 
        hash_table.containsValue(30));
 
        // Checking for the Value '40'
        System.out.println("Is the value '40' present? " + 
        hash_table.containsValue(40));
    }
}

输出:

Initial Table is: {You=30, Welcomes=25, 4=15, Geeks=20}
Is the value '10' present? false
Is the value '30' present? true
Is the value '40' present? false

注意:可以使用任何类型的变体和不同数据类型的组合执行相同的操作。

 

 
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