Java Dictionary keys()用法及代碼示例

Java中的Dictionary類的keys()方法用於獲取字典中存在的鍵的枚舉。

用法:

Enumeration enu = DICTIONARY.keys()

參數：該方法不帶任何參數。

返回值：該方法返回字典鍵的枚舉。

下麵的程序用於說明java.util.Dictionary.keys()方法的用法：
示例1:

// Java code to illustrate the keys() 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 elements 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("The Dictionary is: " + dict); 
  
        // Creating an empty enumeration to store 
        Enumeration enu = dict.keys(); 
  
        System.out.println("The enumeration of keys are:"); 
  
        // Displaying the Enumeration 
        while (enu.hasMoreElements()) { 
            System.out.println(enu.nextElement()); 
        } 
    } 
}

輸出：

The Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
The enumeration of keys are:
10
20
30
15
25

示例2:

// Java code to illustrate the keys() 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 elements into the table 
        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("The Dictionary is: " + dict); 
  
        // Creating an empty enumeration to store 
        Enumeration enu = dict.keys(); 
  
        System.out.println("The enumeration of keys are:"); 
  
        // Displaying the Enumeration 
        while (enu.hasMoreElements()) { 
            System.out.println(enu.nextElement()); 
        } 
    } 
}

輸出：

The Dictionary is: {You=30, Welcomes=25, 4=15, Geeks=20}
The enumeration of keys are:
You
Welcomes
4
Geeks

相關用法

注：本文由純淨天空篩選整理自Chinmoy Lenka大神的英文原創作品 Dictionary keys() Method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。