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    Java.util.IdentityHashMap.containsValue()

    java.util.IdentityHashMap.containsValue()方法用于检查IdentityHashMap中是否由一个或多个键映射特定值。它将Value作为参数,如果该值由映射中的任何键映射,则返回True。

    句法:

    Identity_HashMap.containsValue(Object Value)

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

    返回值:如果检测到值的映射,则该方法返回布尔值true,否则返回false。

    下面的程序说明了java.util.IdentityHashMap.containsValue()方法

    程序1:将字符串值映射到整数键。

    // Java code to illustrate the containsValue() method
    import java.util.*;
    
    public class Identity_Hash_Map_Demo {
        public static void main(String[] args)
        {
    
            // Creating an empty IdentityHashMap
            IdentityHashMap<Integer, String> identity_hash = 
                       new IdentityHashMap<Integer, String>();
    
            // Mapping string values to int keys
            identity_hash.put(10, "Geeks");
            identity_hash.put(15, "4");
            identity_hash.put(20, "Geeks");
            identity_hash.put(25, "Welcomes");
            identity_hash.put(30, "You");
    
            // Displaying the IdentityHashMap
            System.out.println("Initial Mappings are: " +
                                              identity_hash);
    
            // Checking for the Value 'Geeks'
            System.out.println("Is the value 'Geeks' present? " + 
                            identity_hash.containsValue("Geeks"));
    
            // Checking for the Value 'World'
            System.out.println("Is the value 'World' present? " + 
                            identity_hash.containsValue("World"));
        }
    }
    

    输出:

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

    程序2:将整数值映射到字符串键。

    // Java code to illustrate the containsValue() method
    import java.util.*;
    
    public class Identity_Hash_Map_Demo {
        public static void main(String[] args)
        {
    
            // Creating an empty IdentityHashMap
            IdentityHashMap<String, Integer> identity_hash = 
                          new IdentityHashMap<String, Integer>();
    
            // Mapping int values to string keys
            identity_hash.put("Geeks", 10);
            identity_hash.put("4", 15);
            identity_hash.put("Geeks", 20);
            identity_hash.put("Welcomes", 25);
            identity_hash.put("You", 30);
    
            // Displaying the IdentityHashMap
            System.out.println("Initial Mappings are: " + 
                                                 identity_hash);
    
            // Checking for the Value '10'
            System.out.println("Is the value '10' present? " + 
                               identity_hash.containsValue(10));
    
            // Checking for the Value '30'
            System.out.println("Is the value '30' present? " + 
                               identity_hash.containsValue(30));
    
            // Checking for the Value '40'
            System.out.println("Is the value '40' present? " + 
                              identity_hash.containsValue(40));
        }
    }
    

    输出:

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

     
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