如何让JList显示ArrayList？

Question

I'm trying to get a Jlist to display a list of my own Client objects. My Client class DOES have a toString() method which works fine with System.out.print(), and I'm not sure where else my problem could lie.

Here is my code:

private void displayClients(){
    List<Client> clients = new ArrayList<>(this.gym.getClients());
    displayClientsList.setListData(clients);
    displayClientsList.setSelectedIndex(0);
}

Here is the error message:

no suitable method found for setListData(List<Client>)
method JList.setListData(String[]) is not applicable
(argument mismatch; List<Client> cannot be converted to String[])
method JList.setListData(Vector<? extends String>) is not applicable
(argument mismatch; List<Client> cannot be converted to Vector<? extends String>)

Can anyone tell me how to fix this? Thanks :)

Answer 1

The API documents for this method says that it takes a Vector, or an array...

https://docs.oracle.com/javase/7/docs/api/javax/swing/JList.html#setListData(E[])

Try...

displayClientsList.setListData(clients.toArray(new Client[0]));

Or you might want to make a list of strings yourself and show those, for example...

List<String> displayList = clients.stream()
    .map(c -> c.toString())
    .collect(Collectors.toList());

displayClientsList.setListData(displayList.toArray(new String[0]));

Answer 2

A simple way to do this would be like this:

List<Client> clients = new ArrayList<>(this.gym.getClients());
String[] clientArray = new String[clients.size()];
displayClientsList.setListData(clients.toArray(clientArray));

Update: The JList gets as a parameter a String array, so you need to firstly convert your clients list to a String array like this:

String[] clientAarray = clients.stream().map(c -> c.toString()).toArray(size -> new String[size]);
displayClientsList.setListData(clientArray);

Answer 3

Why don't you change displayClientsList from a JList<String> to a JList<Client> and then do the following:

    List<Client> clients = this.gym.getClients();
    displayClientsList.setListData(clients.toArray(new Client[clients.size()]));