Develop Reference

Jpanel textbox no output

I'm working in java using Jpanel and my work is compiling fine however is showing no output. hopefully, someone could tell me why this is. I'm using jscrollpane and I'm calling it at the end idk if it's something to do with the listener or what.
FileDemoPanel.java
package Tutoiral03Task01;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class FileDemoPanel extends JPanel implements ActionListener {
public void actionPerformed(ActionEvent e) {
JButton openBtn, saveBtn;
JTextArea workTa;
openBtn = new JButton ("Open");
openBtn.setEnabled (false);
openBtn.setMnemonic('g');
openBtn.setToolTipText("open button");
setLayout(new BorderLayout());
saveBtn = new JButton ("Save");
saveBtn.setEnabled (false);
saveBtn.setMnemonic('f');
saveBtn.setToolTipText("Save button");
JTextArea logTA = new JTextArea (5, 100);
logTA.setEditable(false);
logTA.setBackground(Color.lightGray);
logTA.setMargin(new Insets(5,5,5,5));
JScrollPane logScrollPane = new JScrollPane(logTA);
add(logScrollPane);
}
}
FileDemo.java
package Tutoiral03Task01;
import javax.swing.*;
public class FileDemo {
public static void main (String[] args){
JFrame frame = new JFrame("Working with files");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new FileDemoPanel());
frame.pack();
frame.setVisible(true);
}
}

The problem is that you create all the buttons and others in a actionperformed method.
This is wrong, because that is used as a ButtonListener, so if you dont press a button nothing will happened. We use to write the GUI frame in the constructor of the class.Then we create an object type of the GUI class. So i think i fixed it and i did some extra changes to make the program more simple. The step i didnt do is to add a ButtonListener, so Buttons do nothing.
i wish it will helps you.
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class FileDemoPanel extends JFrame {
private JPanel panel = new JPanel();
private JButton openBtn = new JButton("Open");
private JButton saveBtn = new JButton ("Save");
private JTextArea workTa;
public FileDemoPanel(){
openBtn.setEnabled (false);
openBtn.setMnemonic('g');
openBtn.setToolTipText("open button");
setLayout(new BorderLayout());
saveBtn.setEnabled (false);
saveBtn.setMnemonic('f');
saveBtn.setToolTipText("Save button");
JTextArea logTA = new JTextArea (5, 100);
logTA.setEditable(false);
logTA.setBackground(Color.lightGray);
logTA.setMargin(new Insets(5,5,5,5));
JScrollPane logScrollPane = new JScrollPane(logTA);
panel.add(openBtn);
panel.add(saveBtn);
panel.add(logTA);
panel.add(logScrollPane);
this.setContentPane(panel);
this.setVisible(true);
this.setResizable(true);
this.setSize(350,150);
this.setTitle("Κεντρική Σελίδα");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
And the mainclass.As you can see is too small.
public class FileDemo {
public static void main (String[] args){
new FileDemoPanel();
}
}

JPanel doesn't add button and text field

I don't understand why the panel.add(txtnum1) and panel.add(button2) doesn't show up when I compile the program. The panel.add(button) works just fine, my compiler doesn't throw any warning or errors, did I miss something?
package gui;
import javax.swing.*;
import java.awt.*;
public class GUI {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setVisible(true);
frame.setSize(new Dimension(300, 500));
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel();
panel.setBackground(Color.GRAY);
frame.getContentPane().add(panel);
JButton button = new JButton("Submit");
panel.add(button);
JTextField txtnum1 = new JTextField();
txtnum1.setPreferredSize(new Dimension(30, 50));
panel.add(txtnum1);
JButton button2 = new JButton("Clear");
panel.add(button2);
}
}

When implementing GUI applications with Swing, I like to have this approach in the code that builds the JFrame (we assume a simple GUI that does not have JPanel containers inside JPanel containers and stuff like that):
Create JFrame and initialize it
Create JPanel
Create GUI components for that panel and add them
Add panel to the JFrame (repeat from 2) for every JPanel inside the JFrame)
Make the JFrame visible on the screen
So, your code would look something like this:
package gui;
import javax.swing.*;
import java.awt.*;
public class GUI {
public static void main(String[] args) {
/* step 1 */
JFrame frame = new JFrame();
frame.setSize(new Dimension(300, 500));
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
/* step 2 */
JPanel panel = new JPanel();
panel.setBackground(Color.GRAY);
/* step 3 */
JButton button = new JButton("Submit");
panel.add(button);
JTextField txtnum1 = new JTextField();
txtnum1.setPreferredSize(new Dimension(30, 50));
panel.add(txtnum1);
JButton button2 = new JButton("Clear");
panel.add(button2);
/* step 4 */
frame.getContentPane().add(panel);
/* step 5 */
frame.setVisible(true);
}
}
Tested and it works in Eclipse.

You should call setVisible(true) at the end, after all components have been added.
Put frame.setVisible(true); at the end and it will work as expected.

usage of BorderLayout

I am having a problem with BorderLayout, that was set to the green JPanel side. It does not display elements on the EAST in a row order. Do I have to combine this with GridBagLayout ? Could someone advice me how should I tackle this problem?
Basically the problem is of displaying objects inside green area below when I am using
Current layout:
My aim is to achieve this layout:
public class GUILayout {
public static void main(String[] args) {
JFrame jf = new JFrame();
JButton jbO = new JButton("CSIS0396");
JButton jbl = new JButton("Final");
JButton jb2 = new JButton("2010");
JButton jb3 = new JButton("Exam");
JPanel panel = new JPanel();
JPanel panel2 = new JPanel();
JButton object_btn = new JButton("Object");
JButton oriented_btn = new JButton("Oriented");
JButton programming_btn = new JButton("Programming");
JButton and_btn = new JButton("and");
JButton java_btn = new JButton("Java");
BorderLayout layout = new BorderLayout();
panel.setLayout(layout);
panel2.setLayout(layout);
panel.add(BorderLayout.CENTER,object_btn);
panel.add(BorderLayout.WEST,oriented_btn);
panel.add(BorderLayout.WEST,programming_btn);
panel.add(BorderLayout.WEST,and_btn);
panel.add(BorderLayout.WEST,java_btn);
panel2.add(BorderLayout.NORTH, jbO);
panel2.add(BorderLayout.SOUTH, jb2);
panel2.add(BorderLayout.WEST, jbl);
panel2.add(BorderLayout.EAST, jb3);
panel.setBackground(Color.GREEN);
panel2.setBackground(Color.RED);
jf.getContentPane().add(panel);
jf.getContentPane().add(panel2, BorderLayout.EAST);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.setSize(400, 300);
jf.setVisible(true);
}
}

don't share same layout for multiple component and use box layout for left panel to positioning buttons
import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GUILayout {
public static void main(String[] args) {
JFrame jf = new JFrame();
JButton jbO = new JButton("CSIS0396");
JButton jbl = new JButton("Final");
JButton jb2 = new JButton("2010");
JButton jb3 = new JButton("Exam");
JPanel panel = new JPanel();
JPanel panel2 = new JPanel();
JButton object_btn = new JButton("Object");
JButton oriented_btn = new JButton("Oriented");
JButton programming_btn = new JButton("Programming");
JButton and_btn = new JButton("and");
JButton java_btn = new JButton("Java");
BorderLayout layout = new BorderLayout();
panel2.setLayout(layout);
panel.setLayout( new BoxLayout(panel, BoxLayout.PAGE_AXIS));
panel.add(object_btn);
panel.add(oriented_btn);
panel.add(programming_btn);
panel.add(and_btn);
panel.add(java_btn);
panel2.add(BorderLayout.NORTH, jbO);
panel2.add(BorderLayout.SOUTH, jb2);
panel2.add(BorderLayout.WEST, jbl);
panel2.add(BorderLayout.EAST, jb3);
panel.setBackground(Color.GREEN);
panel2.setBackground(Color.RED);
jf.setLayout(new BorderLayout());
jf.getContentPane().add(panel ,BorderLayout.WEST);
jf.getContentPane().add(panel2, BorderLayout.EAST);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.setSize(400, 300);
jf.setVisible(true);
}
}

The first problem is that you're having your panels share a layout. You must use a new BorderLayout for each of them.
The second problem is that a BorderLayout can only have one component in each constraint position. When you try to add multiple components to the WEST position, each one replaces the one that was previously in that position:
panel.add(BorderLayout.WEST,oriented_btn);
// Implicitly removes oriented_btn from panel
panel.add(BorderLayout.WEST,programming_btn);
// Implicitly removes programming_btn from panel
panel.add(BorderLayout.WEST,and_btn);
// Implicitly removes and_btn from panel
panel.add(BorderLayout.WEST,java_btn);
The solution is to put them in their own container, such as a Box or a JPanel with a GridLayout:
Box box = Box.createVerticalBox();
// Or:
//JComponent box = new JPanel(new GridLayout(0, 1));
box.add(oriented_btn);
box.add(programming_btn);
box.add(and_btn);
box.add(java_btn);
panel.add(BorderLayout.WEST, box);

Java buttons not showing up on JFrame

I am fairly new to java, and I am starting a sort of glossary program.
At the start, I am trying to use a JFrame with buttons on.
But only 1 button shows up when I run it.
Also, I don't think I am positioning the buttons right.
package glossary;
import java.awt.BorderLayout;
import javax.swing.JFrame;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class Glossary {
public static void main(String[] args) {
JFrame frame = new JFrame("Glossary");
frame.setVisible(true);
frame.setSize(400,200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel1 = new JPanel();
frame.add(panel1);
JButton LookUpWord = new JButton("Look up word");
panel1.add(LookUpWord, BorderLayout.NORTH);
JPanel panel2 = new JPanel();
frame.add(panel2);
JButton SubmitNewWord = new JButton("Submit word");
panel2.add(SubmitNewWord, BorderLayout.SOUTH);
}
}
Please tell me what I am doing horribly wrong!

I think you are just getting mixed up about where to add your components. You probably aren't intending to add the buttons to NORTH and SOUTH, but rather adding the panels to the frame at NORTH and SOUTH. Also, wait until you've added all your components before calling frame.setVisible(true).
Try this:
public static void main(String[] args) {
JFrame frame = new JFrame("Glossary");
frame.setSize(400, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton LookUpWord = new JButton("Look up word"); // create the button
JPanel panel1 = new JPanel(); // create the panel
panel1.add(LookUpWord); // add the button to the panel
frame.add(panel1, BorderLayout.NORTH); // add the panel to the frame
JButton SubmitNewWord = new JButton("Submit word");
JPanel panel2 = new JPanel();
panel2.add(SubmitNewWord);
frame.add(panel2, BorderLayout.SOUTH);
frame.setVisible(true);
}

Add frame.setVisible(true);
Hoping this tutorial help you
How to Make Frames

JButton disappears when adding JTextrea

I'm having an issue with my Java program where I can add a JButton to the panel in JFrame, but when I create an JTextArea object, the JButton disappears?
package sandBox;
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
public class Main {
public static void main(String[] args) {
System.out.println("Hello World");
JFrame frame = new JFrame("Hello world");
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600,500);
frame.setLayout(new BorderLayout());
JButton button2 = new JButton("STOP");
JButton button1 = new JButton("GO");
JTextArea text1 = new JTextArea();
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
panel.add(button1, BorderLayout.SOUTH);
panel.add(button2, BorderLayout.NORTH);
frame.add(panel);
}
}

Remember
BorderLayout will only allow a single component to occupy each of the available positions. Adding another component will cover the previous component
Where possible, always call setVisible after you've created the UI
To actually add all your components, your example doesn't actually add the JTextArea to the container
Someone like...
//...
// frame.setVisible(true);
//...
frame.add(text1);
frame.add(panel, BorderLayout.SOUTH);
frame.setVisible(true);
Might help