Develop Reference

Items in GridBagLayout does not properly align

I'm trying to align 3 items in a GridBagLayout, 2 of the items being on top and 1 item at bottom. Both Items should be the same Size. I have tried to achieve this with BorderLayout and GridBagLayout but no luck.
This is my attempt with GridBagLayout as you can see they are not properly aligned. This is what I tried to do.
Add first item
Set the x to 1
Add second item
Set the y to 1
Add the last item
I was hoping this would work because It doesn't make sense to me why this would not work, Here is the code for it.
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
JTextField oldPkg = new JTextField();
container.add(oldPkg, gbc);
gbc.gridx = 1;
JTextField newPkg = new JTextField();
gbc.gridy = 1;
JTextField apkPath = new JTextField();
container.add(apkPath, gbc);
The result I want to achieve is
I have achieved it with FlowLayout but it doesn't resign packed when the frame is resized, and the bottom bar is a bit big.
How can I achieve this with GridBagLayout or any other layout so it remains the same on size changes?

Sometimes, you need to set back and try a different approach. Maybe starting with and piece of paper, where you can draw the layout and plot out the constraints.
This will lead you to understanding that apkPath needs to start at x of 0 and "span" two columns.
Currently apkPath is using the same x position as newPkg, you need to change it before using it again.
gbc.gridy = 1;
gbc.gridx = 0;
JTextField apkPath = new JTextField();
container.add(apkPath, gbc);
Okay, but now it's the same size as oldPkg, we need to tell GridBagLayout we want to span multiple columns
gbc.gridy = 1;
gbc.gridx = 0;
gbc.gridwidth = 2;
JTextField apkPath = new JTextField();
container.add(apkPath, gbc);
should now allow the textfield to flow over both columns
I might suggest having a look at How to Use GridBagLayout for more details

Slightly off topic:
Might I just suggest not bothering with 90% of the inbuilt layouts and just going with MigLayout.
There is a MigLayout core jar, and MigLayout swing jar. (Don't take the MigLayout SWT jar by mistake, and also don't use the SWT versions in the import statements).
I guess the licence is liberal. But, you can check whether it fits your needs.
http://www.miglayout.com/
(Just a happy user. Not affiliated)
This does a lot in just a few lines:
public class LayoutAnswer extends JFrame {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
LayoutAnswer window = new LayoutAnswer();
window.init();
window.pack();
window.setVisible(true);
window.setLocationRelativeTo(null);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
});
}
private JPanel panel = new JPanel( new MigLayout("insets 10","[300::, grow][400::, grow]","[100:150:200][100:150:200]") );
private JLabel lbl1 = new JLabel("One");
private JLabel lbl2 = new JLabel("Two");
private JLabel lbl3 = new JLabel("Three");
public void init() {
add(panel, BorderLayout.CENTER);
panel.add(lbl1, "");
panel.add(lbl2, "wrap");
panel.add(lbl3, "span 2");
}
}

Java - Can't figure out which layout to use?

I had my layout perfect until I couldn't figure out how to make drag and drop work. So to make the coding easier, I switched my labels on the bottom right side of my program to buttons to allow single clicking to generate an object in the main panel.
Now that I switched them, using BoxLayout, the buttons are not able to be sized for the image to fit perfectly in them, leaving edge space as seen in the photo. I also have a horizontal scroll bar now which I didn't have before with the labels.
I have tried several different layouts to try and fix the size of these buttons, but I can't get things to work right. I just need a vertical scroll bar and I want the buttons to be the exact size of the images, like they are in the panel above them. I tried setting the layout to null like I have in all the other panels and using the setBounds() method and that works perfectly for placement, but then the scroll bar disappears and won't scroll.
Anyone have any suggestions?
Edit: Here is what happens when I use the null layout.

I'd really recommend that you use GridBag layout if you're using swing. The other layouts leave a lot to be desired. It is all a matter of preference and you can lay it out manually if you want--there's no right answer.
The reason I prefer GridBag (or MigLayout--to each their own) is that you have a concept of preferred size for the component and the concept of fills. It has been a while since I coded up Swing (and I'll try to keep it that way!) but you're basically looking for something like:
{
//Pseudo Code, I'd have to go read the API again, I wrote a set of utilities so I wouldn't have to think about it.
GridBagConstraints constraints = ....;
constraints.weightX = 1.0; //fill the area by X
constraints.weightY = 1.0; //fill by Y
constraints.fill = GridBagConstraints.BOTH; //or one...
component.setPreferredSize(image.size());
layout.add(component, constraints);
}
Basically what you're doing is saying "use my preferred size as a minimum" but fill based on these rules.
The alternative--which doesn't use a layout is simply position the components yourself (there's absolutely nothing wrong with this).
{
JPanel panel =...;
panel.setLayout(null);
...
myButton3.setX(0);
myButton3.setY(2 * buttonHeight); //third button
myButton.setSize(myButton.getPreferredSize()); //which I assume you set
...
panel.add(myButton3);
...
}
Anyhow, there's a lot of options. Don't feel like you need to use a layout, write your own. You should care about these things and make it work but you shouldn't suffer. A layout is generally very simple to implement and you shouldn't be afraid to walk away from this.
All that said, GridBag will do what you want. Alternatively, Mig is great and has some nice GUI editors.
UPDATE -> -------------------------------
Here's a concise example--I sincerely do not advocate this style of programming, I just didn't want class spam for the example.
package _tests;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class Grids extends JFrame
{
private static final long serialVersionUID = 1L;
public static void main(String ... args)
{
new Grids().setVisible(true);
}
public Grids()
{
//Null layout example
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(250, 300);
setMinimumSize(new Dimension(285, 300)); //Windows 8 ~ border size + scrollbar
setTitle("Test layouts");
JPanel scrollTarget = new JPanel()
{
private static final long serialVersionUID = 1L;
{
setSize(250, 1000);
setPreferredSize(new Dimension(250, 1000));
//setLayout(null); -- uncomment for absolute
setLayout(new GridBagLayout());
int lastX = 0;
int lastY = 0;
for(int i = 0; i < 5; i++)
{
final String label = "Button " + i;
JButton tmp = new JButton()
{
private static final long serialVersionUID = 1L;
{
setText(label);
setPreferredSize(new Dimension(250, 200)); //Preferred
}
};
tmp.setSize(tmp.getPreferredSize()); //What you're layout usually does..
//add(tmp);
//tmp.setLocation(lastX, lastY);
//lastY += tmp.getHeight();
add(tmp, getButtonConstraint(0, i));
}
}
};
add(new JScrollPane(scrollTarget));
}
private GridBagConstraints getButtonConstraint(int x, int y)
{
GridBagConstraints tmp = new GridBagConstraints();
tmp.fill = GridBagConstraints.BOTH;
tmp.weightx = 1.0;
tmp.weighty = 1.0;
tmp.gridx = x;
tmp.gridy = y;
tmp.anchor = GridBagConstraints.NORTHEAST;
return tmp;
}
}

Controlling textbox height in a Java Swing layout

I have a form, and when it renders using pack, the textboxes have a nice default height. But when I resize it - or in this case, if I override getPreferredSize to make it larger on startup - the textboxes resize proportionally.
I keep going in circles trying to understand the layout manager classes... the related questions that are coming up seem like they're really close, but I'm just not following them!
In the class below, if I comment out the getPreferredSize overload, the textboxes are sized by the system to be "just right". Add getPreferredSize back, or resize manually, and the textbox proportions expand/contract with the form. There's got to be something simple I'm missing!
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.TitledBorder;
public class TestTextBox extends JFrame {
private JTextField jtfRate = new JTextField();//jtfAnnualInterestRate
private JButton jbtComputeLoan = new JButton("Compute Sentence");
// Constructor buids the panel
public TestTextBox() {
// a panel with the fields
JPanel p1 = new JPanel(new GridLayout(5, 2));
p1.add(new JLabel("Annual Interest Rate"));
p1.add(jtfRate);
p1.setBorder(new TitledBorder("This is a border with enough text that I want to see it"));
// a panel with the button
JPanel p2 = new JPanel(new FlowLayout(FlowLayout.CENTER));
p2.add(jbtComputeLoan);
// Put the panels on the frame
add(p1, BorderLayout.CENTER);
add(p2, BorderLayout.SOUTH);
}
#Override
public Dimension getPreferredSize() {
// This will help Pack to pack it up better
return new Dimension(600, 300);
}
public static void main(String[] args) {
TestTextBox jailCell = new TestTextBox();
jailCell.pack(); // Arrange controls compactly based on their properties
jailCell.setTitle("Calculate your Sentence");
jailCell.setLocationRelativeTo(null); // sure, center it, whatever
jailCell.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jailCell.setVisible(true);
}
}
Obviously, this is a case for a GUI layout tool. But this isn't production code, this is a Java class in which I'm trying my best to learn why it works - that way I'll know what the GUI tools are doing.
Update: Thanks to the answer I got, I was able to figure out the basics of the GridBag. It seems pretty closely related to HTML <table>s. It took much longer than it should have, mostly because I kept forgetting , c); to apply the GridBagConstraints to the control! Here's a sample of what the relatively simple add above turned into:
GridBagConstraints c = new GridBagConstraints();
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.gridy = 0;
p1.add(new JLabel("Annual Interest Rate"), c);
c = new GridBagConstraints();
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 1;
c.gridy = 0;
c.weightx = 0.25;
p1.add(jtfRate, c);

The default behaviour of GridLayout is to provide each component with equal amounts of available space. This means, as you make the component larger, they will get bigger, as you make it smaller, the will get smaller.
You could use a GridBagLayout instead, which will allow you to layout your components in a grid pattern but control how much of the cell they should occupy...
Take a look at How to use GridBagLayout for more details...

JLabels to be resized in a GridLayout

I have a very simple Java program (see below). The GridLayout has 20 rows and 4 columns. As you know the elements are supposed to be added horizontally by (GridLayout) definition. However, I get the two elements (labels) placed one above the other, vertically.
I colored them and realised the labels take up the whole row, hence the vertical effect. But then I also used setSize(5,5) with each to make them smaller, however they still take up the whole row. Any advice as to why this happens and how to fix/set smaller size/etc?
public class Sam extends JFrame {
public JButton btn_arr;
public Container c;
public JLabel[] lbl = new JLabel[20];
public Sam()
{
c = getContentPane();
c.setLayout(new GridLayout(20,4));
lbl[1] = new JLabel("Column1");
c.add(lbl[1]);
lbl[2] = new JLabel("Column2");
c.add(lbl[2]);
show();
}
public static void main(String[] args)
{
Sam x = new Sam();
x.setVisible(true);
x.setSize(7500,4500);
}
}

You're only adding two components to the grid so they will fill it up. You need to add more components to the grid as placeholders so that it can place the original JLabels in their proper place, perhaps empty JLabels or JPanels.
As an aside, you should avoid setting the size of any Swing component. Your current size of 7500, 4500 is a bit on the large size.
As a second aside, perhaps you want to use a JTable instead here.
Edit: if you want a GridLayout with 4 columns and variable number of rows, use 0 for your GridLayout row constant:
c.setLayout(new GridLayout(0, 4));
e.g.,
import java.awt.*;
import javax.swing.*;
public class Sam extends JFrame {
public static final int COLUMN_COUNT = 4;
public JButton btn_arr;
public Container c;
public JLabel[] lbl = new JLabel[COLUMN_COUNT];
public Sam() {
c = getContentPane();
c.setLayout(new GridLayout(0, COLUMN_COUNT));
for (int i = 0; i < lbl.length; i++) {
lbl[i] = new JLabel("Column " + (i + 1));
c.add(lbl[i]);
}
}
public static void main(String[] args) {
Sam x = new Sam();
x.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
x.pack();
x.setLocationRelativeTo(null);
x.setVisible(true);
// x.setSize(7500,4500);
}
}
But still I wonder if a JTable wouldn't work better here.

One thing to keep in mind with the GridLayout is it that it is designed to cover the entire containing panel sizing the cells as equally as possible, and elements added to the cells will be expanded to fill the entire cell. So as the cell sizes change, the labels will also change in size. Effectively grid cells force an expansion/contraction in both X and Y direction of all contained elements.
One way to prevent that from happening if you must use the GridLayout is to not add the labels directly to the container that uses the GridLayout, but instead put each label inside a JPanel that uses a FlowLayout (the default) that you can set alignment of either Left, Middle or Right, then add that JPanel to the Grid container. The JPanel will be resized but it will not change the size of the Label.
Or use the GridBagLayout manager. More complex, but once you understand it, it makes life easier. But as Hovercraft mentioned, if what you are trying to do is create a grid with column headers, a JTable might be a better option.

Creating a text field that dynamically resizes its width

I'm making what is basically a toolbar that contains a search field and some buttons. I'd like for the search field to grow in size (just the width) when the parent container gets wider, like when the user adjusts the split pane. Currently, the text field and the buttons will remain the same size and whitespace is added on either side as the container is widened. I can achieve this growing effect by using a BorderLayout in the container and putting the buttons on LINE_END and the text field in the CENTER. The problem I have with this is that the text field now becomes taller than a standard text field and it looks ugly. This behavior makes sense as the BorderLayout manager will give all the extra space (this includes vertical and hortizontal space) to the CENTER text field. I've tried to restrict this vertical growth by placing a maximum size on the text field, but BorderLayout will not honor it.
Here's what I've got:
final JTextField searchField = new JTextField("Enter your search terms");
searchField.setMaximumSize(new Dimension(Integer.MAX_VALUE, 25));
final JPanel controls = new JPanel(new BorderLayout());
controls.add(searchField, BorderLayout.CENTER);
controls.add(new JPanel(){{
add(new JButton("Search")); add(new JButton("I'm Feeling Lucky"));
}}, BorderLayout.LINE_END);
It would seem that this behavior is a commonly desired one and it should be easy to implement, but I've had no luck after looking through all the Oracle/Sun tutorials and Google search results.
Anybody have any solutions to this? I need to stick with standard Java Swing components - no third party libraries please.
Thank you!

I would suggest you to use GridBagLayout , it is complicated but it is the most powerful layout.. When you learn it, you would not have any layout issue.
Here is the sample use of gridbaglayout for this question...
import java.awt.BorderLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class GridBagLayoutExample extends JFrame {
GridBagLayoutExample() {
initUI();
}
private void initUI() {
final JTextField searchField = new JTextField("Enter your search terms");
final JPanel controls = new JPanel(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
c.weightx=1.0;
c.fill=GridBagConstraints.HORIZONTAL;
controls.add(searchField,c);
controls.add(new JPanel(){
{
add(new JButton("Search")); add(new JButton("I'm Feeling Lucky")); }});
setLayout(new BorderLayout());
add(controls, BorderLayout.NORTH);
pack();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new GridBagLayoutExample().setVisible(true);
}
});
}
}

it's a two part problem:
a) all xxSize (xx = min/max/pref) are mere hints to the LayoutManager. Each and every LayoutManager has its own behaviour if/how/when it respects those hints and if/how/when it violates one or more if the overall space is more or less than would fit the sum of pref for all components in the container. No way but learn which does what (documentation is ... ehem ... suboptimal)
b) JTextField is a bit crazy in allowing its height to grow indefinitely if space allows. Implying that even LayoutManagers which respect max (like f.i. BoxLayout) have no chance to do so, max is Integer.MAX_VALUE (or Short.MAX? forgot). To make it behave, subclass and override maxSize to return the pref height:
#Override
Dimension getMaximumSize() {
Dimension max = super.getMaximumSize();
max.height = getPreferredSize().height;
return max;
}

You should be able to use a horizontal BoxLayout.
searchField.setMaximumSize(new Dimension(Integer.MAX_VALUE, 25));
You should not guess at the height of the text field.
Dimension d = searchField.getPreferredSize();
d.width = Integer.MAX_VALUE;
searchField.setMaximumSize(d);
I know you said you don't want to use 3rd party libraries, but as a side note you might want to look at Text Field Prompt. It allows you to display a message that will disapear when you start typing in the text field.

Using BoxLayout.
JTextField search_field = new JTextField("Enter search term");
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.LINE_AXIS));
panel.add(search_field);
This will dynamically change the size of textfield when resizing the frame.