哈希表類keySet()方法 (Hashtable Class keySet() method)

• keySet() method is available in java.util package.

  keySet()方法在java.util包中可用。

• keySet() method is used to return a set of keys to be viewed in a set in this Hashtable.

  keySet()方法用于返回要在此Hashtable集中的一組鍵中查看的鍵。

• keySet() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  keySet()方法是一種非靜態方法，只能通過類對象訪問，如果嘗試使用類名訪問該方法，則會收到錯誤消息。

• keySet() method does not throw an exception at the time of returning keys in a set view.

  在設置視圖中返回鍵時， keySet()方法不會引發異常。

Syntax:

句法：

public Set keySet();

Parameter(s):

參數：

• It does not accept any parameter.

  它不接受任何參數。

Return value:

返回值：

The return type of the method is Set, it returns keys in a set view of this Hashtable.

方法的返回類型為Set ，它在此Hashtable的set視圖中返回鍵。

Example:

例：

// Java program to demonstrate the example // of Set keySet() method of Hashtable import java.util.*;public class KeySetOfHashtable {public static void main(String[] args) {//Instantiate a hashtable object Hashtable ht = new Hashtable();// By using put() method is to// add the linked values in an// Hashtable htht.put(10, "C");ht.put(20, "C++");ht.put(30, "JAVA");ht.put(40, "PHP");ht.put(50, "SFDC");// Display HashtableSystem.out.println("Hashtable: " + ht);// By using keySet() method is to// return th set of keys exists in// Hashtable to be viewed in a setSet s = ht.keySet();// Display Hashtable in a set viewSystem.out.println("ht.keySet(): " + s);} }

Output

輸出量

Hashtable: {10=C, 20=C++, 30=JAVA, 40=PHP, 50=SFDC} ht.keySet(): [10, 20, 30, 40, 50]

翻譯自: https://www.includehelp.com/java/hashtable-keyset-method-with-example.aspx

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