Java Dictionary get()方法及实例

Dictionary类的get()方法用于检索或获取由参数中提到的特定键映射的值。当字典中没有该键的映射时，它返回NULL。

语法

DICTIONARY.get(Object key_element)

参数： 该方法需要一个对象类型的参数key_element，指的是要获取其相关值的键。

返回值： 该方法返回与参数中key_element相关的值。

以下程序用于说明java.util.Dictionary.get()方法的工作：

程序1 :

// Java code to illustrate the get() method
import java.util.*;
  
public class Dictionary_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty Dictionary
        Dictionary<Integer, String> dict
            = new Hashtable<Integer, String>();
  
        // Inserting the values into dictionary
        dict.put(10, "Geeks");
        dict.put(15, "4");
        dict.put(20, "Geeks");
        dict.put(25, "Welcomes");
        dict.put(30, "You");
  
        // Displaying the Dictionary
        System.out.println("Initial Dictionary is: " + dict);
  
        // Getting the value of 25
        System.out.println("The Value is: " + dict.get(25));
  
        // Getting the value of 10
        System.out.println("The Value is: " + dict.get(10));
    }
}

输出。

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

程序2

// Java code to illustrate the get() method
import java.util.*;
  
public class Dictionary_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty Dictionary
        Dictionary<String, Integer> dict
            = new Hashtable<String, Integer>();
  
        // Inserting the values into dictionary
        dict.put("Geeks", 10);
        dict.put("4", 15);
        dict.put("Geeks", 20);
        dict.put("Welcomes", 25);
        dict.put("You", 30);
  
        // Displaying the Dictionary
        System.out.println("Initial Dictionary is: "
                           + dict);
  
        // Getting the value of 25
        System.out.println("The Value is: "
                           + dict.get("Geeks"));
  
        // Getting the value of 10
        System.out.println("The Value is: "
                           + dict.get(20));
    }
}

输出。

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