How to Create Dynamic JComboBoxes for Hierarchical Data?

Creating Dynamic JComboBoxes for Hierarchical Data

When working with data that exhibits a hierarchical structure, such as the one provided in the question, creating dynamic JComboBoxes can greatly enhance user interaction and simplify data selection. To achieve this, multiple ComboBoxModels are required to represent the different levels of hierarchy.

In this particular example, we have three courses (Course1, Course2, Course3) and their corresponding units (A1, A2, B1, B2, B3, B4, C1, C2). To create dynamic JComboBoxes, we first create a ComboBoxModel for each course. These models will hold the units for each course, as follows:

models[0] = new DefaultComboBoxModel(new String[] {"A1", "A2"});
models[1] = new DefaultComboBoxModel(new String[] {"B1", "B2", "B3", "B4"});
models[2] = new DefaultComboBoxModel(new String[] {"C1", "C2"});

Next, we populate the first JComboBox (combo1) with the courses:

combo1 = new JComboBox(new String[]{ "Course 1", "Course 2", "Course 3" });

We then populate the second JComboBox (combo2) with the units for the first course by default:

combo2.setModel(models[0]);

Finally, we add an ActionListener to combo1 to handle selections. When the selected course changes in combo1, the corresponding units are populated in combo2:

@Override
public void actionPerformed(ActionEvent e) {
    int i = combo1.getSelectedIndex();
    combo2.setModel(models[i]);
}

By implementing this approach, we create dynamic JComboBoxes that allow users to select courses and see their corresponding units populated in a linked ComboBox. This dynamic behavior enables intuitive navigation and data selection, especially when dealing with hierarchical or complex data structures.

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