https://www.guru99.com/java-swing-gui.html#3




java GUI summary

* Components (or in Swing, JComponents)

  JComponents are the fundamental primative widgets everything is built from

  JTextField
  JTextArea
  JComboBox
  JLabel
  JList
  JMenuBar
  JOptionPane
  JPanel
  JScrollBar
  JButton

  
* Containers

  Containers contain components
  Container are themselves components
  For creating a GUI, we need at least one container
  Three of the most useful types of containers:

  JPanel  - A pure container, not a window by itself
  JFrame  - A fully functioning window with a title and icons
  JApplet - Usually used in a browser


  Other containers : JToolBar JScrollPane JDialog

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* Simple example with no layout manager
***************************************

import javax.swing.*;

class gui {

  public static void main(String args[]) {
    JFrame frame = new JFrame("My First GUI");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300,300);
    JButton button1 = new JButton("Button 1");
    JButton button2 = new JButton("Button 2");
    frame.getContentPane().add(button1);
    frame.getContentPane().add(button2);
    frame.setVisible(true);
  }
}

***************************************


   Note that we typically create our own class which is an
   extension of JFrame, but has some :
     smart layout manager stuff
     its own variables
     its own special methods

   BorderLayout is the default layout manager of JFrame
   FlowLayout is the default layout manager of JPanel

   Note that a frame can hold JComponents or conatiners

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* The content pane of a window is where you place stuff. It is the
  inner area of the window.

  A JFrame will always have a content pane, even if you don't
  create it.

  You get it with
    frame.getContentPane()

    Container con = getContentPane();
    con.setLayout(flow);
    con.add(princLabel);
        .
        .
        .


  You can also create your own content pane, and then set it to be the frame content pane

    // in class definition 
    BorderLayout bord = new BorderLayout()
    JPanel pane = new JPanel();

      // in the constructor
     pane.setlayout(bord);

     pane.add(comp1, BorderLayout.NORTH)
     pane.add(comp2, BorderLayout.South)

     setContentPane(pane);

***************************************

***************************************
* JFrame()
***************************************
The class JFrame is one of the most important classes

A JFrame object is the top level window in your GUI

If you create your own kind of object, it will just be an
extension of JFrame

Important methods provided by the class JFrame

  public JFrame() - constructor

  public JFrame(String s) - constructor with a title

  public void setSize(int w, int h)

  public void setTitle(String s)

  public void setVisible(boolean b)

  public void setDefaultCloseOperation(int operation)
    (usually "operation" is EXIT_ON_CLOSE)

  public void addWindowListener(WindowEvent e)


You can directly use the class JFrame, and create your
own JFrame object, which will be your GUI window


***************************************

***************************************
* Basic Framework of a java class --> gregThing.java
***************************************

public class gregThing
{

  // all my static variables that come with each gregThing

  int xval;
  double lenghval;
     .
     .
     .


  // the default constructor
  public gregThing()
  {


  }


  // other methods that come with a gregThing

  public void calculateVal()
  {

  }


      .
      .
      .


  // main method
  public static void main(String [] args)
  {

    //usually create one instance of the class
    


  }


}

***************************************
* Basic Framework of a java GUI class --> johnnyFrame.java
***************************************

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class johnnyFrame extends JFrame implements ActionListener
{

  // static variables (include your basic JComponents - Jbutton, JTextField, ...)







  // default constructor
  public johnnyFrame()
  {

  }


  // alternate constructor
  public johnnyFrame(String namestr)
  {

  }


  // Main Method
  public static void main(String[] args)
  {

    johnnyFrame frm = new JohnnyFrame()

    frm.setTitle("Whei")

  }

}