问题
I need to display three levels in a vaadin tree grid. I use the 'setItems' method to set values to the tree grid as per the vaadin documentation. How can I set a third nested level to the grid.
TreeGrid<Project> treeGrid = new TreeGrid<>();
treeGrid.setItems(getProjects(), Project::getSubProjects);
treeGrid.addColumn(Project::getName).setCaption("Name");
treeGrid.addColumn(Project::getStatus).setCaption("Status");
I've followed the code snippet in the vaadin 8.1 documentation https://vaadin.com/docs/-/part/framework/components/components-treegrid.html
回答1:
You have 2 options. Suppose you have something similar to:
public class Project {
private List<Project> subProjects;
public List<Project> getSubProjects(){};
}
the first and simplest solution, is to supply a list of root projects and a child item provider (a means of retrieving the child projects for a given project) to the tree:
treeGrid.setItems(rootProjects, Project::getSubProjects);
alternatively, if you really need to, you can specify the parent for each list of child items, but you may need to do this recursively. From the documentation link you provided:
data.addItems(newProject, newProject.getChildren());
(ortreeGrid.getTreeData().addItems(newProject, newProject.getSubProjects())
)
Fully functional sscce using the first method (stolen from the Vaadin sampler):
public class BasicTreeGrid extends VerticalLayout {
// used to generate some random data
private final Random random = new Random();
public BasicTreeGrid() {
// basic tree setup
TreeGrid<Project> treeGrid = new TreeGrid<>();
addComponent(treeGrid);
treeGrid.addColumn(Project::getName).setCaption("Project Name").setId("name-column");
treeGrid.addColumn(Project::getHoursDone).setCaption("Hours Done");
treeGrid.addColumn(Project::getLastModified).setCaption("Last Modified");
// some listeners for interaction
treeGrid.addCollapseListener(event -> Notification
.show("Project '" + event.getCollapsedItem().getName() + "' collapsed.", Notification.Type.TRAY_NOTIFICATION));
treeGrid.addExpandListener(event -> Notification
.show("Project '" + event.getExpandedItem().getName() + "' expanded.", Notification.Type.TRAY_NOTIFICATION));
// add the list of root projects and specify a provider of sub-projects
treeGrid.setItems(generateProjectsForYears(2010, 2016), Project::getSubProjects);
}
// generate some random projects
private List<Project> generateProjectsForYears(int startYear, int endYear) {
List<Project> projects = new ArrayList<>();
for (int year = startYear; year <= endYear; year++) {
Project yearProject = new Project("Year " + year);
for (int i = 1; i < 2 + random.nextInt(5); i++) {
Project customerProject = new Project("Customer Project " + i);
customerProject.setSubProjects(Arrays.asList(
new LeafProject("Implementation", random.nextInt(100), year),
new LeafProject("Planning", random.nextInt(10), year),
new LeafProject("Prototyping", random.nextInt(20), year)));
yearProject.addSubProject(customerProject);
}
projects.add(yearProject);
}
return projects;
}
// basic parent (or intermediate child) bean used for easy binding
class Project {
private List<Project> subProjects = new ArrayList<>();
private String name;
public Project(String name) {
this.name = name;
}
public String getName() {
return name;
}
public List<Project> getSubProjects() {
return subProjects;
}
public void setSubProjects(List<Project> subProjects) {
this.subProjects = subProjects;
}
public void addSubProject(Project subProject) {
subProjects.add(subProject);
}
public int getHoursDone() {
return getSubProjects().stream().map(project -> project.getHoursDone()).reduce(0, Integer::sum);
}
public Date getLastModified() {
return getSubProjects().stream().map(project -> project.getLastModified()).max(Date::compareTo).orElse(null);
}
}
// basic final child (can not have other children) bean used for easy binding
class LeafProject extends Project {
private int hoursDone;
private Date lastModified;
public LeafProject(String name, int hoursDone, int year) {
super(name);
this.hoursDone = hoursDone;
lastModified = new Date(year - 1900, random.nextInt(12), random.nextInt(10));
}
@Override
public int getHoursDone() {
return hoursDone;
}
@Override
public Date getLastModified() {
return lastModified;
}
}
}
Result:
来源:https://stackoverflow.com/questions/45429492/how-to-set-multiple-levels-in-a-tree-grid-with-vaadin-8-1