The state of the tree selection is characterized by a set of TreePaths, and optionally a set of integers. The mapping from TreePath to integer is done by way of an instance of RowMapper. It is not necessary for a TreeSelectionModel to have a RowMapper to correctly operate, but without a RowMapper getSelectionRows will return null.
A TreeSelectionModel can be configured to allow only one path (SINGLE_TREE_SELECTION) a number of contiguous paths (CONTIGUOUS_TREE_SELECTION) or a number of discontiguous paths (DISCONTIGUOUS_TREE_SELECTION). A RowMapper is used to determine if TreePaths are contiguous. In the absence of a RowMapper CONTIGUOUS_TREE_SELECTION and DISCONTIGUOUS_TREE_SELECTION behave the same, that is they allow any number of paths to be contained in the TreeSelectionModel.
For a selection model of CONTIGUOUS_TREE_SELECTION any time the paths are changed (setSelectionPath, addSelectionPath ...) the TreePaths are again checked to make they are contiguous. A check of the TreePaths can also be forced by invoking resetRowSelection. How a set of discontiguous TreePaths is mapped to a contiguous set is left to implementors of this interface to enforce a particular policy.
Implementations should combine duplicate TreePaths that are added to the selection. For example, the following code
TreePath[] paths = new TreePath[] { treePath, treePath }; treeSelectionModel.setSelectionPaths(paths); should result in only one path being selected: treePath, and not two copies of treePath. The lead TreePath is the last path that was added (or set). The lead row is then the row that corresponds to the TreePath as determined from the RowMapper. @author Scott Violet
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