Avoiding overwriting objects in ArrayList

Question

Stackers. I\'ve been searching the site for my question, but didn\'t find what I was looking for. I\'m stuck with this code:

public class Users{
ArrayList<         


        

Answer 1

If I understood right you're adding new users this way:

ValidateUser newUser = new ValidateUser();
    newUser.setUser("administrator");
    newUser.setPass("asdf123");
    newUser.setBalance(0.8);
    newUser.setType("admin");
    personer.add(newUser);

    newUser.setUser("different admin");
    personer.add(newUser);

however this way the object points to the same reference, thus you must do the following to instantiate a new object:

 newUser = new ValidateUser();
 newUser.setUser("foo");
 personer.add(newUser);

Answer 2

As long as you new ValidateUser() you should be fine. In other words, if you instantiate a new object of the ValidateUser type, and add it to your ArrayList.

You did not clearly explain what you exactly do, but my first guess is that you use the same reference all over again... :)

Example how to make 10 new ValidateUser objects:

// Let's make 10 objects of ValidateUser type
ValidateUser tmpVuser = null;
for (int i = 0; i < 10; i++) {
    tmpVuser = new ValidateUser(); // notice: we always create a new instance
    tmpVuser.setUser("user" + i);
    tmpVuser.setPass("changeme" + i);
    tmpVuser.setBalance(0.8);
    tmpVuser.setType("admin");
    personer.add(tmpVuser);
}

However, it is worth of notice that if ValidateUser was an immutable type (more about it here: http://www.javapractices.com/topic/TopicAction.do?Id=29 ), your code would probably work fine.