Collections in Grid / Add to collections / handle collections

Vaadin 6 / 7 / 8
1

Hello together, can someone tell my how it is possible to handle a class with a collection field (e.g. ArrayList,…).

I have the class Project with some fields like projectname, date and so one. Among that fields I have a LinkedList for gathering Strings (Names of people who work on that project).

public class Project implements Serializable, Cloneable {

private Long id;

private String name = "";

private ProjectDateSpecification specification;

private String description = "";

private String password = "";

private String peopleNeeded;
private List<String> participants = new LinkedList<String>();

methods......


I the class ProjecForm I have this code to add a participants name to the String list of the current project: 

participate2.setClickShortcut(KeyCode.ENTER);
	participate2.addClickListener(e -> {
		
		
		this.addParticipant(project, participateName.getValue());
	//	project.addParticipant(participateName.getValue());
		
		myUI.updateList();
		participateName.clear();
		setVisible(false);

	});
}

private void addParticipant(Project project2, String value) {
	service.addParticipate(project2, value);
}

In my UI i have a grid from which my Projects are accessible.

Attached you can find a picture how it should work.

Unfortunately I add the new participant also to other projects when i click this button and I don’t know why.

Does anyone have a good solution for this issue?

regards Paul