用多个线程迭代和修改jtree

Question

I have a very large JTree and I would like to navigate through all nodes starting from root to leaves.

I need to do some kind of regroupping based on user input.

For example, I want all the nodes whose user object string starts with "a" to be regroupped inside a new node inside the tree.

Initial : Root - Ann, John, Andrew

After : Root - A - Ann Andrew J - John

I was thinking about start iterating and start a bunch of threads for each node and synchronize when creating a new node.

Any thoughts?

Answer 1

A bunch of threads ... unless you mean you are going to construct a new TreeModel in the background by using multiple Thread s and then replace your whole TreeModel of your JTree on the EDT in one go this would be a very bad idea.

Swing components should only be altered on the EDT, so if you are going to re-order nodes from multiple Thread s directly on the TreeModel that is placed on your JTree you will most likely end up with a corrupt representation of your JTree .

Answer 2

As Robin said, doing it directly on the JTree in multiple threads will cause race conditions.

You could copy your TreeModel and alter it. But be aware that you still have to synchronize between your threads. Afterward you could simply call SwingUtilities.invokeLater and set the copied and altered model as the new model for the JTree.

Another idea would be to analyze the data multithreaded, create a (threadsafe) collection with the results and alter the model at the EDT with the results. Having a big tree and little modifications, this would be the fastest way (no copy, no full rebuild of the tree)

Hint: If you are using Java 7, have a look at the Fork/Join-Framework. If not, do it nonetheless to get the idea. Implementation should be easy enough, otherwise there are implementations around.