weakhashmap

WeakHashMap類的keySet()方法 (WeakHashMap 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 retrieve all the key exists in this map to be viewed in a set.

  keySet()方法用于檢索此映射中存在的所有鍵，以在集合中進行查看。

• 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 viewing elements in a set.

  在查看集合中的元素時， 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 existing keys in this map to be viewed in a set.

該方法的返回類型為Set ，它返回此映射中的現有鍵以在集合中查看。

Example:

例：

// Java program to demonstrate the example // of Set keySet() method of WeakHashMap import java.util.*;public class KeySetOfWeakHashMap {public static void main(String[] args) {// Instantiates a WeakHashMap objectMap < Integer, String > map = new WeakHashMap < Integer, String > ();// By using put() method is to add// key-value pairs in a WeakHashMapmap.put(10, "C");map.put(20, "C++");map.put(50, "JAVA");map.put(40, "PHP");map.put(30, "SFDC");// Display WeakHashMapSystem.out.println("WeakHashMap: " + map);// By using keySet() method is to// return the set of of keys exists// in this WeakHashMap to be viewed in a SetSet s = map.keySet();// Display statusSystem.out.print("map.keySet(): ");System.out.println(s);} }

Output

輸出量

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

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

weakhashmap

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