Regarding the difference in "==" and ".equal - java help on CodeGym

I originally wrote my code with "name1 == name2" as the comparing if condition and it didn't work so had to replace it with ".equals". My question is about why it didn't work. From what I understand, "==" checks the place in memory where it is stored rather than a direct comparison. So it wouldn't work with two separately declared objects, but shouldn't it work with simple Strings? I thought that if two declared Strings were exactly the same, then java would store them in the temporary memory at the same location to save space and therefor "==" would work. Anyone know why it doesn't work in this case? Here is my code for reference:

public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String name1 = reader.readLine();
        String name2 = reader.readLine();
        if(name1.equals(name2)){
            System.out.println("The names are identical");
        }else if(name1.length() == name2.length()){
            System.out.println("The names are the same length");
        }
    }
}

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Ivaylo Trifonov

Level 22 , Madrid, Spain

28 April 2019, 07:37

There is a logic in your words. From what I understand, when we create a String it goes into the String pool, and as you say, if there are identical Strings, Java saves memory and reuses just one String. And there is a great chance that "==" works because compares object references. But in your case here I think that assigning:

reader.readLine();

to a String is like creating a new String object, like:

String name1 = new String(reader.readLine());

and therefore is forcing the object allocation. The ".equals" test the String values and you always want to use it. I might be wrong, I still learning Java.

thisisalongname

Level 15 , Spokane, United States

28 April 2019, 15:28

After thinking about it more and testing with Strings where I initialized it inside the code (ie "made a statement") and then some that read from keyboard, I came to the same conclusion. I guess since when it reads from the keyboard it doesn't know what it is before hand so doesn't try to match it with anything in the string pool. Thanks

28 April 2019, 16:44

I see. The Java world is very interesting :)

Regarding the difference in "==" and ".equals"