Setting JButton size while using GridBagLayout

Question

I have this simple JFrame and I want to know how can I set button's height to match exactly text field's height. Why insets don't work on right side of the button? There is no padding between the button and the window border.

import javax.swing.*;
import java.awt.*;

public class MyFrame extends JFrame {
    public static void main(String[] args) {
        new MyFrame();
    }

    public MyFrame() {
        super("My Frame");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLayout(new GridBagLayout());

        GridBagConstraints c;
        final Insets insets = new Insets(4, 4, 4, 4);

        JLabel dbLocationLabel = new JLabel("Database file:");
        c = new GridBagConstraints();
        c.insets = insets;
        c.gridx = 0;
        c.gridy = 0;
        c.anchor = GridBagConstraints.LINE_START;
        this.add(dbLocationLabel, c);

        JTextField dbLocationText = new JTextField();
        c = new GridBagConstraints();
        c.insets = insets;
        c.fill = GridBagConstraints.HORIZONTAL;
        c.gridx = 1;
        c.gridwidth = 5;
        c.gridy = 0;
        c.weightx = 0.1;
        this.add(dbLocationText, c);

        JButton dbLocationButton = new JButton("...");
        c = new GridBagConstraints();
        c.insets = insets;
        c.gridx = 2;
        c.gridy = 0;
        this.add(dbLocationButton);

        this.setSize(500, 150);
        this.setLocation(300, 400);
        this.setVisible(true);
    }
}

Answer 1

1) You should always have a main JPanel. Never put components directly on the JFrame. You will save yourself a lot of future grief.

2) You forgot the constraints on the JButton add.

3) I changed the fill on the JTextField to BOTH to make the JTextField higher.

Here's the changed code.

import javax.swing.*;
import java.awt.*;

public class MyFrame extends JFrame {
    private static final long   serialVersionUID    = 1L;

    public static void main(String[] args) {
        new MyFrame();
    }

    public MyFrame() {
        super("My Frame");
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(new GridBagLayout());

        GridBagConstraints c;
        final Insets insets = new Insets(4, 4, 4, 4);
        final Insets buttonInsets = new Insets(4, 4, 4, 8);

        JLabel dbLocationLabel = new JLabel("Database file:");
        c = new GridBagConstraints();
        c.insets = insets;
        c.gridx = 0;
        c.gridy = 0;
        c.anchor = GridBagConstraints.LINE_START;
        mainPanel.add(dbLocationLabel, c);

        JTextField dbLocationText = new JTextField();
        c = new GridBagConstraints();
        c.insets = insets;
        c.fill = GridBagConstraints.BOTH;
        c.gridx = 1;
//        c.gridwidth = 5;
        c.gridy = 0;
        c.weightx = 0.1;
        mainPanel.add(dbLocationText, c);

        JButton dbLocationButton = new JButton("...");
        c = new GridBagConstraints();
        c.insets = buttonInsets;
        c.gridx = 2;
        c.gridy = 0;
        mainPanel.add(dbLocationButton, c);

        this.add(mainPanel);
        this.setSize(500, 150);
        this.setLocation(300, 400);
        this.setVisible(true);
    }
}