Develop Reference

Java FlowLayout

I am writing some Java code that allows the user to see a frame with JLabel, JTextField and JButton.
I want the JLabel to be called "Count" and I have a problem with FlowLayout.
I want the interface to look like this:
Instead, I have this:
This is my code:
package modul1_Interfate_Grafice;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Exercitiu04 implements ActionListener {
private JFrame frame;
private JLabel labelCount;
private JTextField tfCount;
private JButton buttonCount;
private int count = 0;
public void go() {
frame = new JFrame("Java Counter");
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
frame.getContentPane().add(BorderLayout.CENTER, labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
labelCount.add(tfCount);
buttonCount = new JButton("Count");
labelCount.add(buttonCount);
buttonCount.addActionListener(this);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(350, 150);
frame.setLocation(400, 200);
}
#Override
public void actionPerformed(ActionEvent event) {
count++;
tfCount.setText(count + "");
}
public static void main(String[] args) {
Exercitiu04 a = new Exercitiu04();
a.go();
}
}

Solve it.
Instead of labelCount.setLayout(new FlowLayout());` i should have had
frame.setLayout(new FlowLayout());

From description of JLabel class,
JLabel is:
A display area for a short text string or an image, or both.
But here: labelCount.add(tfCount) and here labelCount.add(buttonCount) you're trying to put a textfield and a button into a label. In this case, positions of button and textfield are controlled by FlowLayout but position of the text in the label is not.
Instead of this, you should put all of your elements in common JPanel, like this:
...
frame = new JFrame("Java Counter");
frame.setLayout(new BorderLayout());
JPanel wrapper = new JPanel(); // JPanel has FlowLayout by default
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
wrapper.add(labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
wrapper.add(tfCount);
buttonCount = new JButton("Count");
buttonCount.addActionListener(this);
wrapper.add(buttonCount);
frame.add(BorderLayout.CENTER, wrapper);
...
And, like MasterBlaster said, you should put swing methods in EDT.

There are only two things you should know about FlowLayout:
a) It is a default layout manager of the JPanel component
b) It is good for nothing.
This trivial layout cannot be achieved with FlowLayout.
When doing layouts in Swing, you should familiarize yourself
with some powerful layout managers. I recommend MigLayout and
GroupLayout.
package com.zetcode;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import net.miginfocom.swing.MigLayout;
/*
Simple UI with a MigLayout manager.
Author Jan Bodnar
Website zetcode.com
*/
public class MigLayoutCounterEx extends JFrame {
public MigLayoutCounterEx() {
initUI();
}
private void initUI() {
JLabel lbl = new JLabel("Counter");
JTextField field = new JTextField(10);
JButton btn = new JButton("Count");
createLayout(lbl, field, btn);
setTitle("Java Counter");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void createLayout(JComponent... arg) {
setLayout(new MigLayout());
add(arg[0]);
add(arg[1]);
add(arg[2]);
pack();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
MigLayoutCounterEx ex = new MigLayoutCounterEx();
ex.setVisible(true);
});
}
}
The example is trivial. You just put the three components into the
cells.
Screenshot:

You shouldn't use setSize when dealing with FlowLayout. Instead use pack(). It makes the window just about big enough to fit all your components in. That should tidy things up for you

JLabel does not appear in the JFrame

I am having trouble implementing JLabel with JFrame. The program needs to show either "Hello" or "World" in the center of the screen when the button "study" is pressed. Also with this being a flashcard program, when study is pressed a word is placed on the middle of the screen and the program is suppose to read from the text field for the user input and print whether it is right or wrong. The problem is that the program is reading the text field after study is pressed so it is printing false before the user can input a answer.
Can someone briefly explain why this is not working and what I can do to fix this issue?
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JButton;
public class NoteCardGUI implements ActionListener {
public static JFrame frame;
public static JPanel panel;
public static JLabel label;
private NoteCard ex;
private JButton study;
public static Box box1 = new Box(), box2 = new Box(), box3 = new Box();
public NoteCardGUI() {
ex = new NoteCard("Hello", "World");
frame = new JFrame("Flash Card");
panel = new JPanel();
study = new JButton("Study");
study.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String resp = NoteCard.getResponse(ex);
String chal = NoteCard.getChallenge(ex);
String a = text.getText();
label = new JLabel(chal, label.CENTER);
label.setAlignmentX(0);
label.setAlignmentY(0);
frame.add(label, BorderLayout.SOUTH);
frame.revalidate();
if(resp.compareTo(a) == 0)
{
label = new JLabel("Correct!");
}
label = new JLabel("Incorrect");
}
});
panel.add(study);
frame.add(panel);
frame.setSize(500, 500);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
new NoteCardGUI();
}
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
}
}

You are adding the label to your frame, but you already have added a JPanel on top of the frame. The solution is to add the label to the panel instead of the frame.
So change: frame.add(label); to panel.add(label);

By default, a JFrame (or rather, its content pane) has BorderLayout. This means that if you add components to it without specifying a constraint, they will be added at the CENTER. But you can't add more than one element at any of the BorderLayout's regions.
So in order for this to work, you need to add the label somewhere else other than the center, or have the panel added with some other, explicit region.
So if you change the add, for example, to:
frame.add(label, BorderLayout.NORTH);
It will work - but you must not forget to also add:
frame.revalidate();
Whenever you add components to your GUI, you should call this when you've added them all, in order for it to rebuild the hierarchy of components as needed.
Another option would be to change the layout manager of the Frame, or to add to the panel.

JAVA - Can't add Text Field and Button to container

I'm trying to do a little program that use some buttons and text field.
I was able to create window with JPanel but don't have idea how to add button and text field
The code I'm using is:
public UI() {
sprites = new HashMap();
// spriteCache = stage.getSpriteCache();
JFrame okno = new JFrame ("VoLTE Script");
setBounds(0,0,SZEROKOSC,WYSOKOSC);
JPanel panel = (JPanel)okno.getContentPane();
panel.setLayout (null);
panel.add(this);
okno.setBounds(0,0,800,600);
okno.setVisible(true);
JTextField pole = new JTextField(10);
JButton przycisk = new JButton("teasda");
przycisk.setPreferredSize(new Dimension(300, 350));
przycisk.setLayout(new BorderLayout());
panel.add(przycisk);
przycisk.setVisible(true);
pole.setBounds (300,300,200,200);
pole.setLayout(null);
pole.setVisible(true);
panel.add(pole);
okno.addWindowListener(new WindowAdapter(){
public void windowClosing (WindowEvent e){
System.exit(0);
}
});
okno.setResizable(false);
createBufferStrategy(2);
strategia=getBufferStrategy();
requestFocus();
// addKeyListener(this);
// addMouseListener(this);
}

You need to use the layout properly, when using border layout you need to tell it which border to use (, BorderLayout.NORTH or something), check out the tutorials at oracles page.
P.S. Think of how your naming your fields etc. Naming something "przycisk" just gives me a reason not to read the code further.

Thank You for help and sorry for Polish names(fixed already).
I was able to add Text Area with scroll.
Looks like problem was in panel.add(this); putted before button and text field.
From my understanding if panel.add(this) is set before panel.add(pole); then panel.add(this) is set in front and pole is added but not seen.
Below my actual working code:
...
public UI() {
sprites = new HashMap();
// spriteCache = stage.getSpriteCache();
JFrame okno = new JFrame ("VoLTE Script");
setBounds(0,0,WIDTH,HEIGHT);
JPanel panel = (JPanel)okno.getContentPane();
panel.setLayout (null);
okno.setBounds(0,0,800,600);
okno.setVisible(true);
JTextArea pole = new JTextArea();
pole.setLayout(null);
pole.setLineWrap(true);
//pole.setBackground(Color.BLACK);
pole.setEditable(false);
JScrollPane scroll = new JScrollPane(pole);
scroll.setBounds(25,250,500,300);
scroll.setVerticalScrollBarPolicy(
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
panel.add(scroll);
panel.add(this);
okno.addWindowListener(new WindowAdapter(){
public void windowClosing (WindowEvent e){
System.exit(0);
}
});
okno.setResizable(false);
createBufferStrategy(2);
strategia=getBufferStrategy();
requestFocus();
// addKeyListener(this);
addMouseListener(this);
}
...

This code is from this site: Example of Java GUI
//Imports are listed in full to show what's being used
//could just import javax.swing.* and java.awt.* etc..
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JComboBox;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JList;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class GuiApp1 {
//Note: Typically the main method will be in a
//separate class. As this is a simple one class
//example it's all in the one class.
public static void main(String[] args) {
new GuiApp1();
}
public GuiApp1()
{
JFrame guiFrame = new JFrame();
//make sure the program exits when the frame closes
guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
guiFrame.setTitle("Example GUI");
guiFrame.setSize(300,250);
//This will center the JFrame in the middle of the screen
guiFrame.setLocationRelativeTo(null);
//Options for the JComboBox
String[] fruitOptions = {"Apple", "Apricot", "Banana"
,"Cherry", "Date", "Kiwi", "Orange", "Pear", "Strawberry"};
//Options for the JList
String[] vegOptions = {"Asparagus", "Beans", "Broccoli", "Cabbage"
, "Carrot", "Celery", "Cucumber", "Leek", "Mushroom"
, "Pepper", "Radish", "Shallot", "Spinach", "Swede"
, "Turnip"};
//The first JPanel contains a JLabel and JCombobox
final JPanel comboPanel = new JPanel();
JLabel comboLbl = new JLabel("Fruits:");
JComboBox fruits = new JComboBox(fruitOptions);
comboPanel.add(comboLbl);
comboPanel.add(fruits);
//Create the second JPanel. Add a JLabel and JList and
//make use the JPanel is not visible.
final JPanel listPanel = new JPanel();
listPanel.setVisible(false);
JLabel listLbl = new JLabel("Vegetables:");
JList vegs = new JList(vegOptions);
vegs.setLayoutOrientation(JList.HORIZONTAL_WRAP);
listPanel.add(listLbl);
listPanel.add(vegs);
JButton vegFruitBut = new JButton( "Fruit or Veg");
//The ActionListener class is used to handle the
//event that happens when the user clicks the button.
//As there is not a lot that needs to happen we can
//define an anonymous inner class to make the code simpler.
vegFruitBut.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent event)
{
//When the fruit of veg button is pressed
//the setVisible value of the listPanel and
//comboPanel is switched from true to
//value or vice versa.
listPanel.setVisible(!listPanel.isVisible());
comboPanel.setVisible(!comboPanel.isVisible());
}
});
//The JFrame uses the BorderLayout layout manager.
//Put the two JPanels and JButton in different areas.
guiFrame.add(comboPanel, BorderLayout.NORTH);
guiFrame.add(listPanel, BorderLayout.CENTER);
guiFrame.add(vegFruitBut,BorderLayout.SOUTH);
//make sure the JFrame is visible
guiFrame.setVisible(true);
}
}
For the future i will recommend you to use the extends JFrame so you can only write a gui like this without initialize a JFrame:
public class CalculatorGUI extends JFrame {
public CalculatorGUI() {
setTitle("Calculator");
setBounds(300, 300, 220, 200);
}}
I suggest you check out a couple of tutorials about how to create a Java Gui or sth.

Cannot resize the textfield in runtime

I changed the code again. But now when I run the code, The text box is very small. Only whn I choose either of the left, center or the right alignment, will the text box size change.
Where did I make the mistake.
I have written the below program. When I click on the left, right or the center button, the program should also read the value in the column size textbox and then automatically resize the message textfield. BUt I cannot seem to do it. Any insight will be greatly appreciated.
package workingwithjtextfields;
package workingwithjtextfields;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.border.*;
public class WorkingwithJTextFields extends JFrame
{
// private int size = 100;
private JTextField jtfMessage = new JTextField(100);
private JTextField jtfColumn = new JTextField(5);
private JRadioButton jrbLeft,jrbCenter,jrbRight;
public static void main(String[] args) //Main program begins here.
{
JFrame frame = new WorkingwithJTextFields();//Instantiating an object.
frame.setTitle("Exercise 17.11");//Setting the frame title.
frame.setSize(470,110);//Setting the size.
frame.setLocationRelativeTo(null);//Setting the location.
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);// Default closing options.
frame.setVisible(true);//Setting visibility to true.
}//End of main program
public WorkingwithJTextFields()
{
// jtfMessage.setColumns(100);
final JPanel parent = new JPanel();
parent.setLayout(new GridLayout(2,1,3,3));
final JPanel p1 = new JPanel();
p1.setLayout(new FlowLayout(FlowLayout.LEFT,30,0));
p1.add(new JLabel("TextField",SwingConstants.CENTER));
jtfMessage= new JTextField("Type anything",SwingConstants.RIGHT);
jtfMessage.setHorizontalAlignment(SwingConstants.CENTER);
p1.add(jtfMessage);
parent.add(p1);
JPanel jpRadioButtons = new JPanel();
jpRadioButtons.setLayout(new GridLayout(1,3));
jpRadioButtons.add(jrbLeft= new JRadioButton("Left"));
jpRadioButtons.add(jrbCenter = new JRadioButton("Center"));
jpRadioButtons.add(jrbRight = new JRadioButton("Right"));
jpRadioButtons.setBorder(new TitledBorder("Horizontal Border"));
final JPanel p2 = new JPanel();
p2.setLayout(new GridLayout(1,2,1,1));
p2.add(jpRadioButtons);
JPanel p3 = new JPanel();
p3.setLayout(new GridLayout(1,1,1,1));
p3.add(new JLabel("Column Size"));
jtfColumn= new JTextField("60",SwingConstants.RIGHT);
jtfColumn.setHorizontalAlignment(SwingConstants.CENTER);
p3.add(jtfColumn);
Border lineBorder = new LineBorder(Color.LIGHT_GRAY,1);
p3.setBorder(lineBorder);
p2.add(p3);
parent.add(p2);
add(parent);
jrbLeft.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
jtfMessage.setHorizontalAlignment(SwingConstants.LEFT);
jrbCenter.setSelected(false);
jrbRight.setSelected(false);
jtfMessage.setColumns(Integer.parseInt(jtfColumn.getText()));
// p1.revalidate();
// p1.repaint();
}
}
);
jrbCenter.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
jtfMessage.setHorizontalAlignment(SwingConstants.CENTER);
jrbLeft.setSelected(false);
jrbRight.setSelected(false);
jtfMessage.setColumns(Integer.parseInt(jtfColumn.getText()));
}
}
);
jrbRight.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
jtfMessage.setHorizontalAlignment(SwingConstants.RIGHT);
jrbCenter.setSelected(false);
jrbLeft.setSelected(false);
jtfMessage.setColumns(Integer.parseInt(jtfColumn.getText()));
}
}
);
}
}

The main problem is with GridLayout.
GridLayout, by design, gives equal width and height to the components in the column/width based on the available space of the parent container.
Instead, try using something like FlowLayout or GridBagLayout which work with the components preferred size instead

Replacing a JPanel with a different JPanel

Hi this is a bit of a basic question. In my code I create a gui in a constructor then nest a ActionListener class to handle button changes. This code will create the gui and the action listener runs through the actionPerformed method correctly. However, I've tried multiple ways to change the panel in the gui but I feel like the way I have the program set up it is not possible for this to work. Sorry if this is a repeat but after searching for a while on S.O. I haven't found a good example that would help me with my problem.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import org.math.plot.Plot2DPanel;
import org.math.plot.plotObjects.BaseLabel;
public class GraphGui extends JFrame {
//default width and height of the GUI
private static final int WIDTH = 1200;
private static final int HEIGHT = 700;
GraphPlot gp = new GraphPlot();
Plot2DPanel plotPanel =gp.determinePlotToPlot("duration");
/**
* This is the constructor that initializes the JFrame and the layout of the GUI.
* The radio buttons are also created here and grouped accordingly.
*/
public GraphGui() {
//title of GUI
setTitle("VibeTech Graph Gui");
//First JRadioButton for date vs duration
JRadioButton durToDate = new JRadioButton("Duration vs. Date");
durToDate.addActionListener(new RadioButtonListener());
durToDate.setActionCommand("duration");
durToDate.setSelected(true);
//JRadioButton for weight vs date
JRadioButton weightToDate = new JRadioButton("Weight vs. Date");
weightToDate.addActionListener(new RadioButtonListener());
weightToDate.setActionCommand("weight");
//JRadioButton for plan type vs date
JRadioButton planToDate = new JRadioButton("Plan vs. Date");
planToDate.addActionListener(new RadioButtonListener());
planToDate.setActionCommand("level");
//button group of the buttons to display them as one group
ButtonGroup group = new ButtonGroup();
group.add(planToDate);
group.add(weightToDate);
group.add(durToDate);
//create JPanel to add objects to
JPanel jplRadio = new JPanel();
jplRadio.setLayout(new GridLayout(0, 1));
//add radio buttons
jplRadio.add(planToDate);
jplRadio.add(weightToDate);
jplRadio.add(durToDate);
Plot2DPanel dvt = new Plot2DPanel();
dvt.addLinePlot("Duration over Time", gp.getDate(), gp.getDuration());
BaseLabel title = new BaseLabel("Duration over Time", Color.RED,
0.5, 1.1);
title.setFont(new Font("Courier", Font.BOLD, 20));
dvt.addPlotable(title);
dvt.setAxisLabels("Time", "Duration");
setLayout(new BorderLayout());
add(jplRadio, BorderLayout.WEST);
add(plotPanel, BorderLayout.EAST);
setSize(WIDTH, HEIGHT);
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
//main method to run program
public static void main(String [ ] args)
{
//create new GUI
#SuppressWarnings("unused")
GraphGui test = new GraphGui();
}
//create a radio button listener to switch graphs on button press
class RadioButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if(e.getActionCommand().equals("duration")) {
plotPanel = gp.determinePlotToPlot("duration");
} else if (e.getActionCommand().equals("weight")) {
plotPanel = gp.determinePlotToPlot("weight");
} else if (e.getActionCommand().equals("level")) {
plotPanel = gp.determinePlotToPlot("level");
}
//here is where I tried to do removes, adds, and validates but
//I have trouble getting to the frame itself to remove the JPanel
//component. I think this is a setup problem.
}
}
}

You would need to add the panel and revalidate/repaint the JFrame for it to appear:
add(plotPanel, BorderLayout.EAST);
revalidate();
repaint();
Better to use CardLayout to manage this type of functionality.

Try using CardLayout for switching between panels. Here is my solution for a similar question: https://stackoverflow.com/a/9377623/544983