Swing GUI in Java: Different elements won't layout properly for me

Question

I'm having trouble getting my GUI to do what I want it to. This is my first time using Swing, so I apologize in advance if this a dumb question. Much of my code is also copy/pasted from the samples at oracle.com, but I think I have a feel for what it's all doing.

In my Swing GUI, I currently have two elements: a JTable and a a JComboBox (which I believe is encompassed by a JScrollPanel). The way I want it formatted is with the ComboBox above the Table, but I can only seem to get it to go either to the left or right of it. I thought that I would be able to use this line:

add(charList, BorderLayout.LINE_START);

where "charList" is my ComboBox, but it doesn't seem to affect anything. No matter what I set it or the other element to, it still stays side to side.

Here is my complete code, all in one file:

import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSeparator;
import javax.swing.JTable;
import javax.swing.SwingConstants;
import javax.swing.table.AbstractTableModel;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;

public class MeleeEdit extends JPanel {
    private boolean DEBUG = false;

    public  String[] attributes = {
            "Initial Walk Velocity", "Walk Acceleration?", "Walk Maximum Velocity", "Slow Walk Max?"    
     };
    public  String[] description = {
            "N/A",
            "N/A, bruh",
            "N/A, BRUH",
            "N/A, BRUH!"    
     };

    public MeleeEdit() {
        super(new GridLayout(1,0));

        String[] characters = { "Captain Falcon", "Young Link", "Donkey Kong", "Doctor Mario", "Falco" };
        JComboBox charList = new JComboBox(characters);
        charList.setSelectedIndex(0);
        //petList.addActionListener(this);


        JTable table = new JTable(new MyTableModel());
        table.setPreferredScrollableViewportSize(new Dimension(500, 600));
        table.setFillsViewportHeight(true);


        table.add(Box.createHorizontalStrut(5));
        table.add(new JSeparator(SwingConstants.VERTICAL));
        table.add(Box.createHorizontalStrut(5));
        table.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));

        //Create the scroll pane and add the table to it.
        JScrollPane scrollPane = new JScrollPane(table);
        //scrollPane.setLayout(BorderLayout.CENTER);

        //Add the scroll pane to this panel.
        add(charList, BorderLayout.LINE_START);
        add(scrollPane, BorderLayout.CENTER);

    }

    class MyTableModel extends AbstractTableModel {
        private String[] columnNames = {"Attribute",
                                        "Value",
                                        "Info",
                                        };
        private Object[][] data = initGrid();

        public Object[][] initGrid(){
            Object[][] tmp = new Object[3][3];
            for(int i = 0; i < 3; i ++){
                tmp[i][0] = attributes[i];
                tmp[i][1] = new Float(4.5);
                tmp[i][2] = description[i];
            }
            return tmp;
        }


        public int getColumnCount() {

            return columnNames.length;
        }
        public int getRowCount() {
            return data.length;
        }
        public String getColumnName(int col) {
            return columnNames[col];
        }
        public Object getValueAt(int row, int col) {
            return data[row][col];
        }
        public Class getColumnClass(int c) {
            return getValueAt(0, c).getClass();
        }

        public boolean isCellEditable(int row, int col) {
            //Note that the data/cell address is constant,
            //no matter where the cell appears onscreen.
            if(col==1)
                return true;
            else
                return false;

        }

        public void setValueAt(Object value, int row, int col) {
            if(value==null)
                return;
            data[row][col] = value;
            fireTableCellUpdated(row, col);
        }
    }

    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("Melee Character Attribute Editor v0.1");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        MeleeEdit newContentPane = new MeleeEdit();
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {

        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

I can't seem to figure out why it isn't working. Any suggestions?

Answer 1

• Change super(new GridLayout(1,0)); to super(new BorderLayout());
• Change add(charList, BorderLayout.LINE_START); to add(charList, BorderLayout.PAGE_START); (personally, I prefer BorderLayout.NORTH, but I'm old school like that)

Take a look at Laying Out Components Within a Container and How to Use Borders for more details