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  1. #1
    guerlando is offline Member
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    Mar 2016
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    Default creating a list of hashmap elements through a for loop

    I'm inside a loop:
    Java Code:
    List<Map<String,String>> myList = new ArrayList<Map<String,String>>()
    for (...) {
            Map<String, String> messageRow = new HashMap<String, String>();
    //ADD Here
    In the comment I made, I wanted to add this messageRow element to myList, but I have doubts about how it will work. Every time the a loop happens, will the last messageRow be erased from memory, and this new one created? If so, wouldn't the messageRow that I added to myList be erased also?

  2. #2
    jim829 is offline Senior Member
    Join Date
    Jan 2013
    Northern Virginia, United States
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    Default Re: creating a list of hashmap elements through a for loop

    Nope. You are storing a reference to the Map in the list. Then you loop and create a new Map and then store that reference in the list. Think about it this way.

    Java Code:
    Map<String, String> foo = new HashMap<>();
    Map<String,String> bar = foo;
    foo = new HashMap<>();
    At this point, bar still has the original hashmap. Assigning a new one to foo doesn't change bar. Same would be true for the list.

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