How to fix only last object from loop being duplicated in Java ArrayList

Question

I am working on a project where I loop through a database and add "Profile" objects to an arraylist (searchResults), but for some reason, the last object created from looping through the resultset is duplicated across the arraylist. Please see code snippet below:

public static ArrayList<Profile> searchResults;


public void showSearchResults(){
    searchResults = new ArrayList<>();        
    searchResults.clear();

    try {
        // create SQL statement object for query
        statement = Connect.toDatabase();

        resultSet = statement.executeQuery (SQL query here)

        while(resultSet.next()){
            Profile newProfile = new Profile();

            newProfile.setUsername(resultSet.getString("username"));
            newProfile.setFirstName(resultSet.getString("first_name"));
            newProfile.setLastName(resultSet.getString("last_name"));
            newProfile.setGender(resultSet.getString("gender"));
            newProfile.setAge(String.valueOf(resultSet.getInt("age")));
            newProfile.setCity(resultSet.getString("city"));                

            searchResults.add(newProfile);
        }

    } catch (SQLException e) {
        // print out exceptions
        e.printStackTrace();
    } finally {
        // close the connections
        Connect.closeConnection(statement, resultSet);
        showResults = true;
    }
}


public ArrayList<Profile> getSearchResults() {
    return searchResults;
}

Any help with this issue would be greatly appreciated. Thanks in advance

sleepToken · Accepted Answer · 2019-11-24 02:53:20Z

1

This is because you have declared your edit: attributes in your profile class as static, and as a general rule, static belongs to a class while non-static belongs to an object.

Static methods are useful if you have only one instance where you're going to use the method.

Since you have multiple instances here (object) = this isn't what you want.

edited Nov 24, 2019 at 2:53

answered Nov 24, 2019 at 1:21

sleepToken

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5 Comments

DoubleU Over a year ago

Unfortunately, your suggestion did not work. I made the arraylist non-static, but I still encountered the same issue

sleepToken Over a year ago

@DoubleU difficult to debug without the code for that class. check for static there otherwise edit your answer to show a minimal reproducible example. thanks!

sleepToken Over a year ago

I guess there's a chance too that your SQL query is returning dups. print those values and make sure maybe

DoubleU Over a year ago

Thanks so much!! I had static attributes in the Profile class as well. I made those non-static and it worked. Again, thanks so much!!

sleepToken Over a year ago

@DoubleU I edited my answer - because I was on track but initially incorrect. I believe you could still have the ArrayList itself static, as long as the profile is non-static. Cheers

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