Java – how to access LinkedList in main from my JFrame button call

:::::: update:::::

I tried to update my JFrame to take LinkedList as a parameter. It looks like

public userLogin(LinkedList<dataUser> ll) {
    initComponents();
 }

My main is to call it

userLogin frame = new userLogin(userLL);
frame.setVisible(true);

Still can't use LinkedList userll in my JFrame

:::::: END UPDATE ::::::

This is my first time using NetBeans and GUI builder I have a class taskmanager that I am using as my main class This class creates some linkedlists and calls my first JFrame GUI, as shown below:

public static void main(String[] args) {
    LinkedList<dataUser> userLL = new LinkedList<dataUser>(); //creates a LL for userData
    LinkedList<task> taskLL = new LinkedList<task>(); //creates a LL for taskData
    LinkedList<task> progressLL = new LinkedList<task>(); //creates a LL for in progress tasks
    LinkedList<task> completeLL = new LinkedList<task>(); //creates a LL for completed tasks

    userLogin frame = new userLogin();
    frame.setVisible(true);

However, in my Userlogin, I cannot access the userll I created This is the code in my submit button:

private void submitBActionPerformed(java.awt.event.ActionEvent evt) {                                        

    String user = jTextField1.getText();
    String userPW = jTextField2.getText();

    try {
        //below userLL is not accessible because it can't be found.
        dataUser.userDataSearch(userLL,userPW);
    } 
    catch (Exception e) {
        JOptionPane.showMessageDialog(this,"was not found","error",JOptionPane.ERROR_MESSAGE);

        return;
    }
}

As the comments in the code say, I can't run this function because I can't access userll (the LinkedList I created in my main program, which starts the JFrame)

Do I have to pass LinkedList into my JFrame as a parameter that it can use? I assume that it is declared in main that it will allow access, but it now seems to be the main local

Solution

You must pass userll as a parameter to the Userlogin class, as follows:

public class userLogin {

    LinkedList<dataUser> userLL

    public userLogin(List userLL){
        this.userLL = userLL;
    }

    //.......
}

Instantiate in your main class as follows: Userlogin frame = new Userlogin (userll);