Java中, IdentityHashMap get()的方法

作者: Arvin Chen 分类: Java 来源: Break易站(www.breakyizhan.com)

IdentityHashMap类的java.util.IdentityHashMap.get() 方法用于检索或获取由参数中提到的特定键映射的值。当map不包含密钥的这种映射时,它返回NULL。

句法:

IdentityHashMap.get(Object key_element

参数:该方法采用对象类型的一个参数key_element,并引用应该获取其关联值的键。

返回值:该方法返回与参数中的key_element关联的值。

下面的程序说明了java.util.IdentityHashMap.get()方法的工作原理

程序1:

// Java code to illustrate the get() method
import java.util.*;

public class Identity_Hash_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty IdentityHashMap
        Map<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);

        // Getting the value of 25
        System.out.println("The Value is: " + 
                                identity_hash.get(25));

        // Getting the value of 10
        System.out.println("The Value is: " + 
                                identity_hash.get(10));
    }
}

输出:

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

程序2:

// Java code to illustrate the get() method
import java.util.*;

public class Identity_Hash_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty IdentityHashMap
        Map<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);

        // Getting the value of "Geeks"
        System.out.println("The Value is: " + 
                          identity_hash.get("Geeks"));

        // Getting the value of "You"
        System.out.println("The Value is: " + 
                            identity_hash.get("You"));
    }
}

输出:

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