Home > Articles > Programming > Java

📄 Contents

  1. Introducing GridBagLayout
  2. GridBagLayout Demonstration Application 1: Ten Dialog Box Scenarios
  3. Whats Next?
  • Print
  • + Share This
Like this article? We recommend

GridBagLayout Demonstration Application 1: Ten Dialog Box Scenarios

Getting the constraints just right is the hard part of working with GridBagLayout. To help you with this task, I’ve created a GBLDemo application (contained in the source.zip for this article) that demonstrates how various constraints combinations affect GUI layouts.

The first combination presents six buttons arranged in a two-row by three-column grid. Listing 1 shows the source code for this combination’s public JPanel buildGUI1() method (excerpted from GBLDemo.java).

Listing 1 buildGUI1().

public JPanel buildGUI1 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Place six buttons in a 2-row by 3-column grid. The first assignment
 // places "Button 1" in the grid’s origin cell.

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 2");
 gbc.gridx = 1;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("?");
 gbc.gridx = 1;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridx = 2;
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

For each button, this method assigns cell column and row numbers to the button’s gridx and gridy constraints variables, respectively. It also invokes panel.add (button, gbc); to associate these constraints with the button. Figure 1 reveals the resulting layout.

Figure 1

Figure 1 The two-row by three-column button layout.

The layout in Figure 1 is similar to a two-row by three-column GridLayout-based layout. As with GridLayout, all display areas have the same dimensions. Unlike with GridLayout, however, not all components have the same size: GridBagLayout sizes each component to its preferred size.

Following a resize, GridLayout displays components with equivalent sizes stretched over their container. In contrast, GridBagLayout displays components with their preferred sizes in the container’s center, unless they’re weighted. (I demonstrate weights later.) Check out Figure 2.

Figure 2

Figure 2 Buttons clump together in a container’s center area after a resize operation.

Combination 2 demonstrates internal padding (which increases the size of a component) on all components in a two-row by three-column grid. Listing 2 shows the source code for this combination’s public JPanel buildGUI2() method.

Listing 2 buildGUI2().

public JPanel buildGUI2 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.ipadx = 10;
 gbc.ipady = 10;

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 2");
 gbc.gridx = 1;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("?");
 gbc.gridx = 1;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridx = 2;
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

A component is padded internally by assigning values to the ipadx and ipady constraints fields, which increases the component’s minimum size. The buildGUI2() method globally assigns values to both fields, resulting in the six larger buttons shown in Figure 3.

Figure 3

Figure 3 Internal padding increases button sizes.

Combination 3 demonstrates external padding (which places empty space between components) on all components in a two-row by three-column grid. Listing 3 shows the source code for this combination’s public JPanel buildGUI3() method.

Listing 3 buildGUI3().

public JPanel buildGUI3 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 2");
 gbc.gridx = 1;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("?");
 gbc.gridx = 1;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridx = 2;
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

A component is padded externally by assigning an Insets object to the insets constraints field. The buildGUI3() method globally assigns this object to insets, resulting in five pixels of empty space to the left of and above each button in Figure 4.

Figure 4

Figure 4 External padding separates buttons.

Combination 4 demonstrates spanning a component, starting with the component’s cell, across all cells except for the last cell in the component’s row. Listing 4 shows the source code for this combination’s public JPanel buildGUI4() method.

Listing 4 buildGUI4().

public JPanel buildGUI4 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 2");
 gbc.gridx = 1;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 gbc.gridwidth = GridBagConstraints.RELATIVE;
 gbc.fill = GridBagConstraints.HORIZONTAL;
 panel.add (button, gbc);

 // Reset to defaults.

 gbc.gridwidth = 1;
 gbc.fill = GridBagConstraints.NONE;

 button = new JButton ("?");
 gbc.gridx = GridBagConstraints.RELATIVE;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

To span a component from its current cell to the next-to-last cell in its row, assign GridBagConstraints.RELATIVE to the gridwidth field and GridBagConstraints.HORIZONTAL to the fill field. The result is shown in Figure 5.

Figure 5

Figure 5 Button 4 fills its entire display area up to (but not including) the last cell in its row.

Combination 5 demonstrates spanning a component, starting with the component’s cell, across all cells in the component’s row. Listing 5 shows the source code for this combination’s public JPanel buildGUI5() method.

Listing 5 buildGUI5().

public JPanel buildGUI5 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 2");
 gbc.gridx = 1;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 gbc.gridwidth = GridBagConstraints.REMAINDER;
 gbc.fill = GridBagConstraints.HORIZONTAL;
 panel.add (button, gbc);

 // Reset to defaults.

 gbc.gridwidth = 1;
 gbc.fill = GridBagConstraints.NONE;

 button = new JButton ("?");
 gbc.gridx = GridBagConstraints.RELATIVE;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

To span a component from its current cell to the last cell in its row, assign GridBagConstraints.REMAINDER to the gridwidth field and GridBagConstraints.HORIZONTAL to the fill field. The result is shown in Figure 6.

Figure 6

Figure 6 Button 4 fills its entire display area, up to and including the last cell in its row.

Buttons ? and 6 are not shown in Figure 6 because in its size calculations GridBagLayout ignores components added to a row after a component has been added whose gridwidth constraint is set to GridBagConstraints.REMAINDER. You must enlarge the GUI to see these buttons.

Combination 6 increases the display area of button 1 from one cell to two cells. Although button 2 is absent, the grid remains set to two rows by three columns. Listing 6 shows the source code for this combination’s public JPanel buildGUI6() method.

Listing 6 buildGUI6().

public JPanel buildGUI6 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 gbc.gridwidth = 2;
 panel.add (button, gbc);

 // Reset to defaults.

 gbc.gridwidth = 1;

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("?");
 gbc.gridx = 1;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridx = 2;
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

The display area of button 1 is increased to two cells by assigning 2 to its gridwidth constraint variable. (This variable is later reset to its default of 1 so that subsequent buttons are not affected.) Figure 7 shows this button centered in its display area.

Figure 7

Figure 7 The display area for button 1 occupies two cells.

Combination 7 is nearly identical to combination 6. The only difference is the presence of button 2, which occupies part of the expanded display area of button 1. The source code for this combination’s public JPanel buildGUI7() method is shown in Listing 7.

Listing 7 buildGUI7().

public JPanel buildGUI7 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 gbc.gridwidth = 2;
 panel.add (button, gbc);

 // Reset to defaults.

 gbc.gridwidth = 1;

 button = new JButton ("Button 2");
 gbc.gridx = 1;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("?");
 gbc.gridx = 1;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridx = 2;
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

When a component is added to a previously added component’s display area, GridBagLayout overlaps the subsequently added component with the previously added component. In Figure 8, the previously added button 1 overlaps the subsequently added button 2.

Figure 8

Figure 8 Button 1 overlaps button 2.

Combination 8 demonstrates that assigning a positive integer to gridwidth (and also to gridheight) to increase the display area can be problematic. Listing 8 shows the source code for this combination’s public JPanel buildGUI8() method.

Listing 8 buildGUI8().

public JPanel buildGUI8 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 gbc.gridwidth = 2;
 gbc.gridheight = 2;
 gbc.fill = GridBagConstraints.BOTH;
 panel.add (button, gbc);

 return panel;
}

Unless components surround a component whose display area is to be increased, GridBagLayout doesn’t increase the size of the display area. As Figure 9illustrates, GridBagLayout hasn’t increased the display area of button 1 to two cells by two cells.

Figure 9

Figure 9 Button 1 did not resize as expected.

Combination 9 corrects the problem with combination 8 by surrounding button 1 (on the right and below) with four button components. Listing 9 shows the source code for this combination’s public JPanel buildGUI9() method.

Listing 9 buildGUI9().

public JPanel buildGUI9 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 gbc.gridwidth = 2;
 gbc.gridheight = 2;
 gbc.fill = GridBagConstraints.BOTH;
 panel.add (button, gbc);

 // Reset to defaults.

 gbc.gridwidth = 1;
 gbc.gridheight = 1;
 gbc.fill = GridBagConstraints.NONE;

 button = new JButton ("Button 2");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 2;
 panel.add (button, gbc);

 button = new JButton ("Button 5");
 gbc.gridx = 1;
 gbc.gridy = 2;
 panel.add (button, gbc);

 return panel;
}

GridBaglayout checks for a button immediately to the right of, on each row of, immediately below, and on each column of the display area for button 1. The presence of these buttons results in button 1 obtaining (and sizing to) its two-row by two-column display area, as shown in Figure 10.

Figure 10

Figure 10 After being surrounded by other buttons, button 1 resizes appropriately.

The final combination demonstrates changing the anchor value of button 1 and using weights, which results in a layout that’s very similar to the layout shown earlier in Figure 7. The source code for this combination’s public JPanel buildGUI10() method is shown in Listing 10.

Listing 10 buildGUI10().

public JPanel buildGUI10 ()
{
 JPanel panel = new JPanel ();
 panel.setLayout (new GridBagLayout ());
 GridBagConstraints gbc = new GridBagConstraints ();

 // Set global constraints.

 gbc.insets = new Insets (5, 5, 0, 0);
 gbc.weightx = 1.0;
 gbc.weighty = 1.0;

 JButton button = new JButton ("Button 1");
 gbc.gridx = 0;
 gbc.gridy = 0;
 gbc.gridwidth = 2;
 gbc.anchor = GridBagConstraints.LINE_END;
 panel.add (button, gbc);

 // Reset to defaults.

 gbc.gridwidth = 1;
 gbc.anchor = GridBagConstraints.CENTER;

 button = new JButton ("Button 3");
 gbc.gridx = 2;
 gbc.gridy = 0;
 panel.add (button, gbc);

 button = new JButton ("Button 4");
 gbc.gridx = 0;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("?");
 gbc.gridx = 1;
 gbc.gridy = 1;
 panel.add (button, gbc);

 button = new JButton ("Button 6");
 gbc.gridx = 2;
 gbc.gridy = 1;
 panel.add (button, gbc);

 return panel;
}

Figures 1–5, 7, and 8 reveal the default center anchor constraint. For variety, I’ve repositioned button 1 in its display area via the following line (see Figure 11):

gbc.anchor = GridBagConstraints.LINE_END;
Figure 11

Figure 11 Button 1 appears on the right side of its display area.

Figure 2 revealed buttons clumped together in their container’s center because the weight constraints were ignored. Because buildGUI10() assigns equal values to these constraints for all buttons, extra space is distributed equally among the buttons, as Figure 12 shows.

Figure 12

Figure 12 Extra space is distributed equally among all buttons when the GUI in Figure 11 is resized.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020