Develop Reference

Using WrapLayout with multiple adjacent JPanels is causing Panel sizing issues

I have 3 adjacent JPanels that each use WrapLayout to display a variable number of 1x16 grids.
It works great for the panel which contains the most 1x16 grids, however, the other two panels' dimensions seem to be determined by the panel that contains the most 1x16 grids. If, for example, panels 1 and 2 have only one 1x16 grid respectively, but panel 3 has ten 1x16 grids spread across two rows, then panel 1 and 2 both have a 1x16 grid-sized empty space beneath their respective 1x16 grids.
I basically want to get each panel's resizing to operate independently of the other panels. I've looked through camickr's src code for WrapLayout and can't quite work out what I should change to get the desired result.
In terms of code, it's tricky to know how to include a succinct and instructive section, as the code is quite spread out and I'm not sure what part is causing this issue. I'm just setting the panels' layout as a left-justified WrapLayout.
I've included an image below which might provide some context. The image shows part of two of the three JPanels (coloured cyan) and the accompanying title JLabel for one of those JPanels (coloured green). The 1x16 grids on each panel are managed using camickr's WrapLayout. All three cyan JPanels are contained within a larger display JPanel that has then been packed into a JScrollPane (hence the grey scroller to the right of the image).
Any help would be really appreciated.
Here's another image I created that shows the issue a little more clearly. The third panel in the image wraps to a new row to display all the 1x16 grids that it contains, and in so doing, doubles the height of the other two panels, despite them not needing to resize.
Here's how I want the GUI to display:

Judging from the desired behaviour vs the actual behaviour images, the problem lies in the LayoutManager you use to lay out the 3 panels into their parent panel/frame (which I am guessing is a GridLayout because the 3 panels have equally distributed sizes). If so, use some other LayoutManager, such as a vertical BoxLayout.
An example code and tutorial can be found in the Oracle's corresponding one (the actual code sample of which, can be found in this link with fancy code coloring, or here as plain text).

I created the following GUI.
I created a JFrame. I created one main JPanel to place inside the JFrame. The main JPanel uses a GridBaglayout to separate three cyan JPanels.
Each cyan JPanel calculates a preferred size based on the number of black JPanels placed in the cyan JPanel. Change the boxesPerRow value to get a different number of boxes per row.
Each black JPanel is created with a preferred size of 20 x 80 pixels;
Here's the complete runnable code. A minimal reproducible example, in other words.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class BoxesGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new BoxesGUI());
}
#Override
public void run() {
JFrame frame = new JFrame("Boxes");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createMainPanel() {
JPanel panel = new JPanel(new GridBagLayout());
panel.setBackground(Color.BLACK);
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.LINE_START;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.insets = new Insets(5, 5, 5, 5);
gbc.weightx = 1.0;
gbc.gridx = 0;
gbc.gridy = 0;
panel.add(createCyanPanel(1), gbc);
gbc.gridy++;
panel.add(createCyanPanel(1), gbc);
gbc.gridy++;
panel.add(createCyanPanel(20), gbc);
return panel;
}
private JPanel createCyanPanel(int count) {
JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEADING, 5, 5));
panel.setBackground(Color.CYAN);
JPanel dummyPanel = createBlackPanel();
Dimension d = dummyPanel.getPreferredSize();
int boxesPerRow = 8;
int width = (d.width + 5) * boxesPerRow + 5;
int height = ((count + boxesPerRow - 1) / boxesPerRow) * (d.height + 5) + 5;
panel.setPreferredSize(new Dimension(width, height));
for (int i = 0; i < count; i++) {
panel.add(createBlackPanel());
}
return panel;
}
private JPanel createBlackPanel() {
JPanel panel = new JPanel();
panel.setBackground(Color.BLACK);
panel.setPreferredSize(new Dimension(20, 80));
return panel;
}
}

Why don't size and preferredSize make this label bigger?

I'm building up a panel that will go in a larger program; the following program still illustrates my question, but it looks a bit more complicated than it absolutely has to because there are places I will add things later.
package sandbox;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class SpacingPlay extends JFrame
{
private static final long serialVersionUID = 1L;
public static void main(String[] args)
{
SpacingPlay sp = new SpacingPlay();
sp.setVisible(true);
}
public SpacingPlay()
{
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new DragNDropPanel();
add(panel);
pack();
}
class DragNDropPanel extends JPanel
{
private static final long serialVersionUID = 1L;
public DragNDropPanel()
{
JPanel currentImagePanel = getCurrentImagePanel();
JPanel leftPanel = new JPanel();
leftPanel.setLayout(new BoxLayout(leftPanel, BoxLayout.PAGE_AXIS));
leftPanel.add(currentImagePanel);
// other things will go here; I cut them out to make this simpler.
setLayout(new BorderLayout());
// put things in a containing panel so that they aren't stretched being in the WEST part of a borderlayout.
JPanel leftContainingPanel = new JPanel();
leftContainingPanel.add(leftPanel);
add(leftContainingPanel, BorderLayout.WEST);
}
private Component createStandardSpace()
{
return Box.createRigidArea(new Dimension(0, 15));
}
private JPanel getCurrentImagePanel()
{
JPanel currentImagePanel = new JPanel();
currentImagePanel.setLayout(new BoxLayout(currentImagePanel, BoxLayout.PAGE_AXIS));
JLabel currentImageLabel = new JLabel("none");
currentImageLabel.setBorder(BorderFactory.createDashedBorder(Color.BLUE));
currentImageLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
Dimension defaultLabelSize = new Dimension(150,150); // was expecting this to enlarge the label.
currentImageLabel.setPreferredSize(defaultLabelSize);
currentImageLabel.setSize(defaultLabelSize);
JButton clearButton = new JButton("Clear");
clearButton.setAlignmentX(Component.CENTER_ALIGNMENT);
clearButton.setBorder(BorderFactory.createLineBorder(Color.GREEN));
currentImagePanel.add(currentImageLabel);
currentImagePanel.add(createStandardSpace());
currentImagePanel.add(clearButton);
currentImagePanel.setBorder(BorderFactory.createLineBorder(Color.ORANGE));
return currentImagePanel;
}
}
}
I would like the currentImageLabel to be a standard size; I intend for it to get different images put into it during the program, and want it to get these without changing size. My idea was to set a size and preferred size and then scale the images I put there to that size.
However, the defaultLabelSize doesn't have the effect I thought it would. The label goes into a boxLayout panel; it is added, then a rigid space, then a button. I expected the label to be the default size, not shrunk to min allowed. I've put in colored borders to try to understand better what's happening; it appears that the preferred size is honored for the overall boxLayout panel, but not for the placement of the button below the label. EDIT: In other words, I want the button below the label to be placed below the label when the label is forced to be bigger. But the size I put on the label doesn't seem to work.
What do I need to do to fix the size of currentImageLabel?

Not 100% why the label is only sized to the text and not the (hard coded) preferred size. I have not been able to duplicate this behaviour using other combinations of panels and layout managers.
You are using pack so all components should be sized to their preferred sizes.
Dimension defaultLabelSize = new Dimension(150,150); // was expecting this to enlarge the label.
currentImageLabel.setPreferredSize(defaultLabelSize);
currentImageLabel.setSize(defaultLabelSize);
A few comments:
Setting the size will never work. The layout manager will always override the size/location based on the rules of the layout manager.
The layout manager can use (or ignore) the preferred, minimum and maximum sizes of a component. In the case of the BoxLayout is does attempt to use the preferred size but will respect the minimum and maximum sizes (depending on the available space in the parent panel).
What do I need to do to fix the size of currentImageLabel?
So, to achieve your desired goal of a fixed preferred size for the JLabel you can use:
Dimension defaultLabelSize = new Dimension(150,150); // was expecting this to enlarge the label.
currentImageLabel.setPreferredSize(defaultLabelSize);
currentImageLabel.setMinimumSize(defaultLabelSize);
currentImageLabel.setMaximumSize(defaultLabelSize);
//currentImageLabel.setSize(defaultLabelSize);
Edit:
was looking for why this doesn't seem to work
For further clarification, change your original code to:
currentImageLabel.setPreferredSize(defaultLabelSize);
System.out.println(currentImageLabel.getPreferredSize());
System.out.println(currentImageLabel.getMinimumSize());
System.out.println(currentImageLabel.getMaximumSize());
You will see the min/max sizes of the label are not affected.
From point 2 above you will see that the BoxLayout is respecting the maximum size.
Therefore, by also overriding the maximum size, you allow the label to be displayed at is preferred size.
However, when you calculate the preferred size of the "currentImagePanel" the ( hardcoded) preferred size of the label is used in the preferred size calculation of the panel, so that panel is displayed at the preferred size.
Another note. The "leftContainingPanel" is not needed. You can just add the "leftPanel" to the BorderLayout.WEST, since the BorderLayout will respect the width of the component you add.

How to create a fluid 2-column GridLayout within a ScrollPane?

I have done tons of searching over the past two hours, and I've given up. The image below shows what I am trying to achieve (don't judge my drawing it's late and I made it in paint quickly):
Basically, I want a JScrollPane to have a JPanel with a 2-column GridLayout, and as I add elements I want the GridLayout to expand downward. I want the elements to use their Preferred Size and to NOT expand within the GridLayout.
Currently I have a JScrollPane and a JPanel with a GridLayout, and a JPanel containing the grid with a FlowLayout. As a test, I add 10 buttons to the grid. Here's my current code:
// Setup main panel
JPanel pnlUsers = new JPanel(new GridLayout(0, 2));
pnlUsers.setOpaque(true);
pnlUsers.setBackground(Color.GREEN);
// Setup GridLayout Container
JPanel pnl2 = new JPanel();
pnl2.setOpaque(false);
pnl2.add(pnlusers);
// Setup scrollpane
JScrollPane scrUsers = new JScrollPane(pnl2);
scrUsers.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrUsers.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
scrUsers.setOpaque(false);
scrUsers.getViewport().setOpaque(false);
scrUsers.setBorder(null);
// Add users
for (int i = 0; i < 10; i++) {
pnlUsers.add(new JButton("Button " + (i + 1));
}
This gives a very good result, with the buttons using their preferred size as seen in the image below:
Unfortunately, the buttons are still not filling the horizontal space. So, I attempted to make pnl2 a BoxLayout instead and add some vertical glue...
// Setup GridLayout Container
JPanel pnl2 = new JPanel();
pnl2.setLayout(new BoxLayout(pnl2, BoxLayout.Y_AXIS));
pnl2.setOpaque(false);
pnl2.add(pnlusers);
pnl2.add(Box.createVerticalGlue());
I also created my own temporary button class that sets the preferred size to use the minimum size:
public class TempButton extends JButton {
public PLTempButton(String msg) {
super(msg);
this.setPreferredSize(this.getMinimumSize());
}
}
Which resulted in the following:
This is much better, but there's still a problem. If there are not enough buttons to cause the JScrollPane to scroll, the buttons height are not consistent and will resize as you resize the window vertically. Why?
Obviously when I add 100 buttons, they use their preferred size:
Maybe I'm just not understanding the differences between minimum, preferred and maximum size? But I want the buttons to use the height they're set even if there aren't enough to cause the scroll-pane to, well, scroll. What can I do to fix this?

1) How do I even get a GridLayout within a ScrollPane?
Create a JPanel
Apply a GridLayout to the JPanel
Wrap the JPanel in a JScrollPane
For example
JPanel panel = new JPanel(new GridLayout(0, 2));
JScrollPane scrollPane = new JScrollPane(panel);
// Add the scroll pane to what ever parent container you're using
2) How do I get said GridLayout to expand horizontally, including the added components?
That doesn't make sense with regards to all previous part of the question, you said "and have it slowly expand downward the more things I add"
Having said that, the "basic" answer is, you configure the GridLayout and let it do it's job. The above example is configured for 2 columns and n number of roes
3) How would I add a "margin" to the components?
That's a broad answer, you could:
Make use of the horizontal and vertical gap properties of the GridLayout
Use a compound layout and adjust the insets of the an appropriate layout manager (like GridBagLayout)
Recommendations
I would recommend reading through Laying Out Components Within a Container to get a better understanding of the layout managers.
Remember, you not stuck to using one.
I would also recommend reading through How to Use Scroll Panes as you're asking basic questions about the API which are better covered through the tutorials

The following mre demonstrates creating a JPanel with GridLayout warped by JScrollPane and setting its horizontal and vertival gaps.
The Jpanel is added using a BorderLayout (the default layout manager of JFrame content pane) which allows it to expand:
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class SwingMain {
private String text ="Growing ";
private JPanel grid;
private JFrame f;
SwingMain() {
creategui();
}
void creategui(){
f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo(null);
JButton addComponentBtn = new JButton("Add Component");
addComponentBtn.addActionListener(e-> addComponent());
f.add(addComponentBtn, BorderLayout.PAGE_START);
grid = new JPanel(new GridLayout(0, 2, 10, 10)); //any number of rows, 2 columns, H and V gap
f.add(new JScrollPane(grid), BorderLayout.CENTER);
f.pack();
f.setVisible(true);
}
void addComponent() {
grid.add(new JLabel(text) );
text +="."; //make text longer so JLable grows
f.pack();
}
public static void main(String[] args) {
new SwingMain();
}
}

How to fill Cells of GridbagLayout with the controls in Swing?

I need to design a swing GUI which has a JFrame with a Menu on top and another main panel having three more panels in center and a separate panel in the bottom of the panel. The required design of the UI is as below
But when I run my swing application I get the output like this (all the panels are packed in the center of the window)
Below is my code
import java.awt.*;
import javax.swing.*;
public class FrontEndView {
private JFrame mainFrame;
private JPanel mainPanel,subPanelUp,subPanelDown,panelLeft,panelRight,panelCenter,panelDown;
private JScrollPane scrollPane;
private JList logViewList;
private JPanel panel1;
public FrontEndView(){
this.prepareGUI();
}
public void prepareGUI(){
mainFrame=new JFrame("GUI");
Toolkit tk = Toolkit.getDefaultToolkit();
int xSize = ((int) tk.getScreenSize().getWidth());
int ySize = ((int) tk.getScreenSize().getHeight());
mainFrame.setSize(xSize,ySize);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setResizable(true);
mainFrame.setLayout(new BorderLayout());
mainPanel=new JPanel();
mainPanel.setLayout(new GridBagLayout());
mainPanel.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
GridBagConstraints gridbagConstMain = new GridBagConstraints();
GridBagConstraints gridbagConstSub = new GridBagConstraints();
subPanelUp=new JPanel();
subPanelUp.setLayout(new GridBagLayout());
subPanelUp.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
panelLeft=new JPanel();
panelLeft.setBorder(BorderFactory.createTitledBorder("Message Defs"));
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
gridbagConstSub.weightx = 0.5;
gridbagConstSub.gridx = 0;
gridbagConstSub.gridy = 0;
subPanelUp.add(panelLeft, gridbagConstSub);
panelCenter=new JPanel();
panelCenter.setBorder(BorderFactory.createTitledBorder("Main Workspace"));
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
gridbagConstSub.weightx = 0.5;
gridbagConstSub.gridx = 1;
gridbagConstSub.gridy = 0;
subPanelUp.add(panelCenter, gridbagConstSub);
panelRight=new JPanel();
panelRight.setBorder(BorderFactory.createTitledBorder("Script Viewer"));
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
gridbagConstSub.weightx = 0.5;
gridbagConstSub.gridx = 2;
gridbagConstSub.gridy = 0;
subPanelUp.add(panelRight, gridbagConstSub);
mainPanel.add(subPanelUp,gridbagConstMain);
subPanelDown=new JPanel();
subPanelDown.setLayout(new BorderLayout());
panelDown=new JPanel();
panelDown.setBorder(BorderFactory.createTitledBorder("Log View"));
logViewList= new JList();
panelDown.add(logViewList);
gridbagConstSub.fill = GridBagConstraints.HORIZONTAL;
//gridbagConst.ipady=20;
//gridbagConst.weightx = 0.0;
gridbagConstSub.gridwidth = 5;
gridbagConstSub.gridx = 0;
gridbagConstSub.gridy = 0;
subPanelDown.add(panelDown,BorderLayout.PAGE_END);
mainPanel.add(subPanelDown, gridbagConstSub);
scrollPane=new JScrollPane(mainPanel,ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
mainFrame.add(scrollPane);
mainFrame.setVisible(true);
}
public static void main(String[] args){
FrontEndView frontEnd = new FrontEndView();
}
}
I want to fill the GridBagLayout's cells with the relevant panel/control it holds as shown in the design and also each panel should have its controls filled inside (I need to add a JList inside the panelDown whose size should be the size of the panelDown JPanel).Simply I don't need any extra space visible in my JFrame. Please guide me on what is missing in my code.

I would suggest you can use nested panels with different layout managers to solve the problem.
The default layout of a frame is a BorderLayout.
So you could create a panel and add it to the PAGE_END so it displays the entire width at the bottom.
Then you can create another panel that uses a GridLayout. You can then add 3 child panels to this panel and each panel can use its own layout. Then you add this panel to the CENTER of the frame. As the frame size changes the extra spaces will be allocated to the CENTER so the panels will dynamically grow.
Edit:
Too many panels for me to take the time to understand what is happening
I was suggesting a structure like this:
frame (which by default uses a BorderLayout)
--- CENTER
panel using GrigBagLayout
childPanel1
childPanel2
childPanel3
---- PAGE_END
JScrollPane containing the JList
When you create the JList the basic code would be:
JList list = new JList(...);
list.setVisibleRowCount(5);
JScrollPane scrollPane = new JScrollPane( list );
There is no need to create a panel just to add the list to another panel. The point of setting the visible row count is to give the JList a fixed height. Scrollbars will then appear in the scroll pane as needed.
Now that the PAGE_END has a fixed height component all the reset of the space will go to the component that you add to the CENTER of the frame.
all the panels are packed in the center of the window)
The panels are displayed at their preferred sizes when you use the GridBagLayout. If the total size of all the panels is less than the size of the scrollpane then they will be in the center. If you want the panels to fill the space available, then I believe you need to use the weightx/y constraints. Read the section from the Swing tutorial on How to Use GridBagLayout which describes all the constraints.
That is why I suggested a GridLayout instead. It will make all the panels the same size and will fill the viewport of the scroll pane without playing with constraints.
mainFrame.add(menubar,BorderLayout.NORTH);
That is not how you add a menubar to the frame.
You should be using:
mainFrame.setJMenuBar(menuBar);
You were told this in your last question. Why did you not listen to the advice??? Why should we take the time to help when you don't pay attention to what is suggested.

Based on your instructions I changed my design in a way all of the outer panels are used with Border Layout and the inner most ones with more controls were used with Grid, GridBag and FlowLayouts based on the requirement. In that way the entire design could be done nicely.
Also if a particular panel within a cell of a layout needs to be expanded, I used the setPreferredSize(new Dimension(int,int)) whenever required.

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.