CODEWITHSUNDEEP
javaswinguser-interfacearraylist
Shadow1349
Shadow1349

Reputation: 771

How to add user input to ArrayList?

I have the following code:

public ArrayList[] username = new ArrayList[1];
public ArrayList[] password = new ArrayList[1];

public void save(String username, String password){
    String uname = userField.getText();
    String pword = passField.getText();

    username.add(uname);
    password.add(pword);
}

I am trying to make an ArrayList of usernames and passwords (using Window Builder) and add to it when someone wants to create a new user/pass. However I get an error saying "The method add(String) is undefined for the type String."

How do I fix and how do I make it so that the size of my array list can grow as new users are added?

Upvotes: 0

Views: 2081

Answers (3)

Vamsi Chilamakurthi
Vamsi Chilamakurthi

Reputation: 16

Hope you are using java version compatible with generics(1.5 or more).You should give the type parameter as String like Steve said.

You can also create a user class

public class User{
 String uname;
 String pwd;
 public User(u,p){
   uname=u;
   pwd=p; 
 }
}

and create an ArrayList of those user objects in the main class

ArrayList<User> list=new ArrayList<>();

and add those user objects with values retrieved from the fields to the list

list.add(new User(uname,pword))

Upvotes: 0

OneMoreError
OneMoreError

Reputation: 7728

Why are you maintaining the usernames and passwords in two different lists ?

Your assumption is based that on matching the indexes of both the lists, and then fetching the usernames and passwords for one specific user.

You should avoid doing that. Use a more suited data structure like a map, which maintains a mapping between a key and a value.

public class UsernamePassword
{

    private Map<String, String> map = new HashMap<String, String>();

    public void save(String username, String password){
        String uname = userField.getText();
        String pword = passField.getText();

        map.put(unmae, pword);
    }
}

Upvotes: 2

Steve Kuo
Steve Kuo

Reputation: 63064

public ArrayList[] username = new ArrayList[1];

creates an array of ArrayList. What you want is a an ArrayList of Strings.

public ArrayList<String> usernames = new ArrayList<String>();

It is good practice to "program to the interface", in this case usernames is a List, whose implementation just happens to be an ArrayList.

public List<String> usernames = new ArrayList<String>();

Upvotes: 2

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