IdentityHashMap類keySet()方法 (IdentityHashMap 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 get a set of all the existing keys in this IdenityHashMap to be viewed in a Set.

  keySet()方法用于獲取此IdenityHashMap中所有現有鍵的集合，以在Set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 returning the key set.

  返回鍵集時， 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 Set view of all the existing keys in this IdenityHashMap.

方法的返回類型為Set ，它返回此IdenityHashMap中所有現有鍵的Set視圖。

Example:

例：

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

Output

輸出量

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

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