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javaswingjtree

Displaying data from the database on Java JTree

I have a database with two columns named colNode,colLeaf

When I read data from the database and display it on the JTree

while (resultSet.next()) {
            DefaultMutableTreeNode url = new DefaultMutableTreeNode(resultSet.getString("colNode"));
            mutableTreeNode.add(url);
            url.add(new DefaultMutableTreeNode(resultSet.getString("colLeaf")));
        }

I would like if the value already exists on JTree colNode then colLeaf will be appended to the.I want to get the results in Figure 2 Please help me

Current output:

Current output

Desired output:

Desired output

Solution

  • I assume you mean, that you want to group all the colLeaf with the same colNode?

    I'd start by doing one of two things, either use the SQL to group and/or sort your results by colNode, this way you could monitor the current "group" and when it changes, create a new TreeNode

    Something like...

    DefaultMutableTreeNode rootNode = ...;
DefaultMutableTreeNode groupNode = null;
String currentGroup = null;
while (resultSet.next()) {
    String group = resultSet.getString("colNode");
    if (currentGroup == null || !currentGroup.equals(group)) {
        currentGroup = group;
        group = new DefaultMutableTreeNode(group);
        rootNode.add(groupNode);
    }
    group.add(new DefaultMutableTreeNode(resultSet.getString("colLeaf")));
}

    for example.

    Or, use somekind of Map, to map all the colNode values under the same key (colLeaf)

    Map<String, List<String>> mapGroups = new HashMap<>(25);
while (resultSet.next()) {
    String group = resultSet.getString("colNode");
    List<String> members = mapGroups.get(group);
    if (members == null) {
        members = new ArrayList<>(25);
        mapGroups.put(group, members);
    }
    members.add(resultSet.getString("colLeaf"));
}

    You would then use the mapGroups to generate your TreeNodes based on the key/value groups.

    for example.

    Personally, I think the first option is more efficient, but might require a more complex query, the second option is slower and requires more overhead, but models the data in manner which is similar to that which you are trying to achieve