Removing panel borders

[Chris Zaremba]

Suddenly my application has come together and I'm just going through cleaning everything up for submission but I've hit on a problem. The following code is an example

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Testing extends JFrame {

    public Testing() {

        setDefaultCloseOperation(EXIT_ON_CLOSE);

        setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        JPanel topPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
        topPanel.setBackground(Color.GREEN);
        c.gridx = 0;
        c.gridy = 0;
        c.anchor = GridBagConstraints.EAST;
        JLabel topLabel = new JLabel("top");
        add(topLabel, c);

        c.gridx = 1;
        c.gridy = 0;
        c.anchor = GridBagConstraints.WEST;
        JTextField topText = new JTextField(20);
        JButton topButton = new JButton("Button");
        topPanel.add(topText);
        topPanel.add(topButton);
        add(topPanel, c);

        c.gridx = 0;
        c.gridy = 1;
        c.anchor = GridBagConstraints.EAST;
        JLabel bottomLabel = new JLabel("bottom");
        add(bottomLabel, c);

        c.gridx = 1;
        c.gridy = 1;
        c.anchor = GridBagConstraints.WEST;
        JTextField bottomText = new JTextField(5);
        add(bottomText, c);

        pack();
        setVisible(true);

    }

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

I want to get rid of the margin/inset/padding shown in green in the example screen shot to get the left sides of the text boxes to line up. I've tried adding empty borders and a few other things but can't get rid of it.

topPanel.setBorder(new EmptyBorder(0, 0, 0, 0));

Does anyone have an answer?

[David Byron]

Chris Zaremba wrote:I want to get rid of the margin/inset/padding shown in green in the example screen shot to get the left sides of the text boxes to line up. I've tried adding empty borders and a few other things but can't get rid of it.

According to the API, there's a constructor that allows you to specify those gaps:

The API wrote:
FlowLayout(int align, int hgap, int vgap)
Creates a new flow layout manager with the indicated alignment and the indicated horizontal and vertical gaps.

Try:

        JPanel topPanel = new JPanel(new FlowLayout(FlowLayout.LEFT, 0, 0));

[Dennis Grimbergen]

you forgot to add this:

c.insets = new Insets(0, 0, 0, 0);

[David Byron]

Dennis Grimbergen wrote:you forgot to add this:

c.insets = new Insets(0, 0, 0, 0);

The green margin is actually occurring on topPanel, which has a FlowLayout, not on TestingMargin, which has a GridBagLayout. So importing java.awt.Insets and then specifying

        c.gridx = 0;
        c.gridy = 0;
        c.insets = new Insets(0, 0, 0, 0);  

actually has no effect whatsoever on his unwanted space.

[Chris Zaremba]

Thank you very much. The hgap and vgap settings do control this. It's easy when you know what you're looking for.