setAutoExpandLevel is not working for TreeViewer

Question

I created TreeViewer and I put setAutoExapandLevel for the tree

treeViewer = new TreeViewer(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL);
treeViewer.setContentProvider(new TreeContentProvider());
treeViewer.setLabelProvider(new TreeLabelProvider());
treeViewer.setAutoExpandLevel(3);
treeViewer.setInput(new Model());

the problem that it is not auto expand for the tree

Do you have any idea why it is not working ?

score 2 · Accepted Answer · edited May 23 '17 at 10:25

Are you sure the model contains all the data when setInput() is called?

internalExpandToLevel(Widget widget, int level) (where expanding takes place) is called on inputChanged(Object input, Object oldInput). If at the time setInput is called the model is empty, no node will be expanded. Even if you later add nodes and call refresh.

To prove this, I changed my snippet from an answer for another question.

Run this code as it is, then run it with the empty field initialized to true. You will see the difference.

static boolean empty = false;

public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());

    TreeViewer treeViewer = new TreeViewer(shell, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL);
    treeViewer.setContentProvider(new DummyContentProvider());
    treeViewer.setAutoExpandLevel(3);
    treeViewer.setInput("root");

    empty = true;
    treeViewer.refresh();

    shell.setSize(200, 200);
    shell.open();
    while (!shell.isDisposed()) {
        if (!display.readAndDispatch()) {
            display.sleep();
        }
    }
    display.dispose();
}

private static class DummyContentProvider implements ITreeContentProvider {

    @Override
    public Object[] getElements(Object inputElement) {
        return this.getChildren(inputElement);
    }

    @Override
    public Object[] getChildren(Object parentElement) {
        if (!empty) {
            return new Object[0];
        }
        switch ((String) parentElement) {
            case "root":
                return new String[]{"a", "b"};
            case "a":
                return new String[]{"1"};
            case "b":
                return new Object[]{"1", "2"};
            case "1":
                return new Object[]{"x", "y"};
            default:
                return new String[0];
        }
    }

    @Override
    public Object getParent(Object element) {
        return null;
    }

    @Override
    public boolean hasChildren(Object element) {
        return this.getChildren(element).length > 0;
    }

    @Override
    public void dispose() {
    }

    @Override
    public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
    }
}

setAutoExpandLevel is not working for TreeViewer

1 Answers1