JTable Left and Upper Lines are invisible

Question

I am trying to show some data on the JTables:

private JTable table1 = new JTable() {
    
    
    private static final long serialVersionUID = 1L;
    
    @Override
    public boolean isCellEditable(int row, int column) {
        return false;
    }

};

private JScrollPane secTabFirst() {

    Object [][] data = {{"90"},{"1700"},{"60"},{"0.7"}, {"Globular"}, {"Sinusoidal"}};
    
    String[] columnNames = {"Parameters"};
    
    DefaultTableModel model = new DefaultTableModel(data, columnNames);
    
    table1.setModel(model);
    
    table1.setTableHeader(null);
    table1.setShowHorizontalLines(true);
    table1.setShowVerticalLines(true);
    //table1.setPreferredSize(new Dimension(150,240));
    //table1.setMaximumSize(new Dimension(150,240));
    
    
    JScrollPane tb1 = new JScrollPane(table1);
    
    tb1.setVisible(true);
    
    return tb1;
}

public static void main(String args[]){
 
 JPanel panel = new JPanel();

 panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));

 panel.add(secTabFirst());

}  

The JTables are shown like these:

But the upper and left lines of the table are invisible. Also, it displays 2 dark-boxes after placing the tables in JScrollPane.

How can I make the lines visible and the dark-boxes disappear?

Thanks,

MB

Answer 1

I tried to replicate your issue without any success, a JTable will never show the top and left borders by default, but this is not an issue as its usually expected to be rendered inside a JScrollPane. As @HovercraftFullOfEels mentioned try giving us an Short, Self Contained, Correct (Compilable), Example

import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.border.EmptyBorder;
import javax.swing.table.DefaultTableModel;

public class TestApp {

    public TestApp() {
        initComponents();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(TestApp::new);
    }

    private void initComponents() {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel panel = new JPanel();
        panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
        panel.setBorder(new EmptyBorder(10, 10, 10, 10));

        JTable table = new JTable() {
            private static final long serialVersionUID = 1L;

            @Override
            public boolean isCellEditable(int row, int column) {
                return false;
            }
        };

        Object[][] data = {{"90"}, {"1700"}, {"60"}, {"0.7"}, {"Globular"}, {"Sinusoidal"}};
        String[] columnNames = {"Parameters"};
        DefaultTableModel model = new DefaultTableModel(data, columnNames);
        table.setModel(model);
        table.setTableHeader(null);

        JScrollPane pane = new JScrollPane(table); // borders for top and left will be rendered thanks to JScrollPanes borders
        panel.add(pane);

        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
    }

}

Update:

You can however set a Border yourself which will ensure the top and left border lines are drawn:

table.setBorder(new LineBorder(Color.GRAY, 1));

Which produces (JTable is not in a JScrollPane in the below screenshot to show the borders without interference):