集合類unmodifiableMap()方法 (Collections Class unmodifiableMap() method)

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

  unmodifiableMap()方法在java.util包中可用。

• unmodifiableMap() method is used to get a non-modifiable view of the given Map (map).

  unmodifiableMap()方法用于獲取給定Map(地圖)的不可修改視圖。

• unmodifiableMap() method is a static method, it is accessible with the class name and if we try to access the method with the class object then also we will not get any error.

  unmodifiableMap()方法是一個靜態方法，可以使用類名進行訪問，如果嘗試使用類對象訪問該方法，那么也不會出現任何錯誤。

• unmodifiableMap() method does not throw an exception at the time of returning unmodifiable view of the given map.

  返回給定地圖的不可修改視圖時， unmodifiableMap()方法不會引發異常。

Syntax:

句法：

public static Map unmodifiableMap(Map map);

Parameter(s):

參數：

• Map map – represents the map object for which a non-modifiable view is to be retrieved.

  地圖地圖 –代表要檢索其不可修改視圖的地圖對象。

Return value:

返回值：

The return type of this method is Map, it returns an unmodifiable view of the given map.

此方法的返回類型為Map ，它返回給定map的不可修改視圖。

Example:

例：

// Java program to demonstrate the example // of Map unmodifiableMap() method of collectionsimport java.util.*;public class UnmodifiableMapOfCollections {public static void main(String args[]) {// Instantiates a linked hashmap objectMap < Integer, String > lhm = new LinkedHashMap < Integer, String > ();// By using put() method is to add//objects in a linked hashmap lhm.put(10, "C");lhm.put(20, "C++");lhm.put(30, "JAVA");lhm.put(40, "PHP");lhm.put(50, "SFDC");// Display Linked HashMapSystem.out.println("linked hashmap: " + lhm);// By using unmodifiableMap() method is to// represent the linked hashmap in unmodifiable viewMap m = Collections.unmodifiableMap(lhm);//We will get an exception when we//try to add an object in an unmodifiable map/* mm.put(60,"COBOL");*/} }

Output

輸出量

linked hashmap: {10=C, 20=C++, 30=JAVA, 40=PHP, 50=SFDC}

翻譯自: https://www.includehelp.com/java/collections-unmodifiablemap-method-with-example.aspx

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