Java Dictionary put()用法及代码示例

字典的put()方法用于在字典中插入映射。这意味着可以将特定键及其值映射到特定字典中。

用法:

DICTIONARY.put(key, value)

参数：该方法有两个参数，都属于Dictionary的Object类型。

key:这是指需要插入字典以进行映射的关键元素。
value:这是指以上键将映射到的值。

返回值：该方法返回键所映射到的值。如果键未映射到任何值，则返回NULL。

以下程序用于说明java.util.Dictionary.put()方法的用法：
示例1:

// Java code to illustrate the put() 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 values into the 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); 
  
        // Inserting existing key along with new value 
        String returned_value = (String)dict.put(20, "All"); 
  
        // Verifying the returned value 
        System.out.println("Returned value is: " + returned_value); 
  
        // Displaying the new table 
        System.out.println("New Dictionary is: " + dict); 
    } 
}

输出：

Initial Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
Returned value is: Geeks
New Dictionary is: {10=Geeks, 20=All, 30=You, 15=4, 25=Welcomes}

示例2:

// Java code to illustrate the put() 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 values into the 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); 
  
        // Inserting existing key along with new value 
        String returned_value = (String)dict.put(50, "All"); 
  
        // Verifying the returned value 
        System.out.println("Returned value is: " + returned_value); 
  
        // Displaying the new table 
        System.out.println("New Dictionary is: " + dict); 
    } 
}

输出：

Initial Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
Returned value is: null
New Dictionary is: {10=Geeks, 20=Geeks, 30=You, 50=All, 15=4, 25=Welcomes}

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注：本文由纯净天空筛选整理自Chinmoy Lenka大神的英文原创作品 Dictionary put() Method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。