It's all about Java

Consider Below points before choosing List concrete implementations for your use case:  ArrayList is a linear data structure and  re-sizable/dynamic array   Initial size can be given. and if not given the default size is 10   It is always good practice to give initial size and advised not to give very large number as size   Good programmers prefer ArrayList to LinkedList if retrieval operations is done more frequently than insertion and deletions of elements.   Better choose LinkedList if insertion and deletion operations are done frequently compared to retrieval operations.   Lists are not sorted. if required use Collections.sort() to sort   Collections.sort() uses optimized merge sort [tim sort] on ArrayList   However legacy merge sort also can be used using a switch. But it is going to be deprecated  in near future  The major difference between ArrayList and LinkedList is RandomAccess behavior...

Unlike AWT, Java Swing tool kit provides feasibilty to create custom components and containers. To understand Java GUI toolkits more clearly, please read my other articles on Swing and AWT.  In this article I focus more on building custom components. Let us see how to create simple Rounded JButton. The below program demonstrates How rounded JButton can be created and added to a JFrame.   Program: import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.GridLayout; import java.awt.Shape; import java.awt.geom.Ellipse2D; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JTextField; import javax.swing.SwingUtilities; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class RoundedJButton extends JButton { /** *  */ private static final long serialVersionUID = 1L; public RoundedJButton(String title) { super(title); Dimension size = getPreferredSize(); size.w...

This article is continuation of previous post JFrame usage demo . Please read it before continuing. This post uses the same example code shown in  JFrame usage demo  with JLabel changes and introduces layout manager BorderLayout. Layout Manager: Layout manager is responsible to arrange components on containers. Usually every swing container is created with a default layout manager but can be changed with setLayout() api. For example JFrame uses BorderLayout as default layout amanger. Java program for JLabel 1  2   import java.awt.BorderLayout; 3   import java.awt.Color; 4   import java.awt.Font; 5  6   import javax.swing.JFrame; 7   import javax.swing.JLabel; 8   import javax.swing.SwingUtilities; 9  10  /** 11   * 12   * Simple class to demonstrate JLabel of swing toolkit 13   * 14   * @author Nagasharath 15   * 16  ...

This post helps in understanding usage of JFrame class with an example Swing toolkit categorizes components into 2 types. They are: Containers Controls Containers allows Controls to be arranged on them. JPanel, JFrame and JDialog are few which are frequently used. Controls are components like Buttons, labels, tables etc. These controls are arranged on containers using different layout managers. All Swing class names starts with J stands for J ava which symbolizes swing is pure java!   Layout Managers: Layout manager is responsible for laying out controls on containers according to the business requirement. Example layout managers are BorderLayout, GridLayout, GridBagLayout and FlowLayout. Few points about JFrame: JFrame is considered as a main window of the application.for almost all swing based applications All other controls and containers are created as child components of JFrame JFrama holds special components like  Menu bar, Tool bar etc...

Every Java programmer must read and understand the following books. 1. Effective Java 2. Concurrency in practice Effective Java: This book is authored by Joshua Bloch. He took the major role in authoring the java.util package which is [collection framework] one of the java core libraries. He explains the best practices that every programmer should consider while writing java programs. Some of them are: Contract between hashcode() and equals() of Object class when programmer overrides one of these methods in their classes Exceptions concurrency: Inter thread communication, synchronization etc Immutable Objects The above points are few among others. Concurrency in practice: This book gives complete explanation about how efficient concurrency is achieved in java programs using concurrency utility classes which were introduced in Java 5 version. This book is authored by: Brian Goetz Tim peierls Joshua Bloch Joseph Bowbeer David Holmes and Doug Lea ...

Internals of Java Virtual Machine are explained very clearly in the below blog by James Blooms.  Internals of JVM by James Blooms

Simple program which demonstrates Swing/AWT Grid layout: This post is intended to the beginners of swing/awt. This below program creates a JFrame with 2 labels, 2 textfields and 2 buttons. import java.awt.GridLayout; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPasswordField; import javax.swing.JTextField; /**  * @author Nagasharath Kopalle  *  * Simple program to demontrate Gridlayout  *  */ public class GridLayoutDemo extends JFrame { private JLabel labelName = null; private JTextField textFieldName = null; private JLabel labelPassword = null; private JPasswordField passwordFieldPassword = null; private JButton buttonSubmit = null; private JButton buttonCancel = null; /** * */ public GridLayoutDemo() { initComponents(); } /** * instantiates components and adds properties. */ void initComponents() { this.setTitle("Grid Layout Dem...

Eclipse Oxygen Java editor Shortcuts helps in editing source code more comfortably. Frequently used default shortcuts are listed below.  Description Shortcut Delete Line CTRL + D Copy Line CTRL + ALT + Down Arrow Add method level, class level, member level Comments SHIFT + ALT + J Format Java Source code CTRL + SHIFT + F Make line commented CTRL + / Make multiple lines [block] commented   CTRL + SHIFT + / Search selected similar word within the source document CTRL + K Select line from beginning to end SHIFT + End key Select line from end to beginning SHIFT + Home key Select Word by word in same line CTRL + SHIFT + Right Arrow Move line above ALT + Up Arrow Move line below ALT + Down Arrow Shortcuts can ...

1. Since Swing is not thread safe, it is not at all a good practice to launch a UI Container like JFrame, JDialog etc in main Thread. 2. Doing so leads to incorrect behavior of java GUI. 3. To avoid this, Swing toolkit has predefined API as part of JFC. 4.    a. SwingUtilities.invokeAndWait(Runnable r);        b. SwingUtilities.invokeLater(Runnable r); 5. Which part of the code must be in UI Thread?         a. setVisible(true);         b. show(); [deprecated]  and c. pack();       6. Call to these methods mentioned in 5(a), 5(b), and 5(c) must happen in one of the methods mentioned in point 4(a) and point 4(b). That's enough. :)          Example :                        public static void main(String[] args){                         ...

This post is intended to beginners of java swing toolkit programmers. It is a simple java program which demonstrates the swing based File explorer GUI. import java.awt.GridLayout; import java.io.File; import java.lang.reflect.InvocationTargetException; import java.util.Arrays; import java.util.List; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTree; import javax.swing.SwingUtilities; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; import javax.swing.event.TreeModelListener; import javax.swing.tree.TreeModel; import javax.swing.tree.TreePath; /**  * @author NagasharathK  *  */ public class FileExplorer extends JFrame { private JTree fileManagerTree = null; public FileExplorer() { initComponents(); } /** * Initializes components */ private void initComponents() { this.getContentPane().add(new JScrollPane(createFileManagerTree(...

Swing controls are of two types they are Containers and components. components are arranged on a containers. example components are JLabel, JButton etc and example containers are JPanel, JFrame and JDialog etc. these components are arranged on a container with the help of layout managers. Few layout managers available in swing toolkit are 1. FlowLayout [Jframe's Default layout manager] 2. GridLayout 3. BorderLayout [JPanel's Default layout manager] 4. GridBagLayout. 5. Custom Layout manager The custom layout amanger is useful to design programmer's own layout manager. Usually this is useful when any of the available layout managers does not give the needy result. apart of these above all layout managers, few third party libraries are also available they are 1. DesignGridLayout 2. Mig Layout etc Design grid Layout Gridlayout is one of the most simple and flexible layout managers. layout manager is used to arrange the components on a container with proper mar...

After understanding and using swing toolkit, I understood that there is a allot of scope to develop Custom components easily. I have developed a component called JForm which basically a button and its selection pops up a window if it is not visible. Technically the JForm component is a combination of 2 components they are: 1. JButton 2. Window JButton is a API of swing toolkit where as Window is a API of AWT. Behaviour of JForm: JForm is a usual button like JButton. but it is glued to a Window component. this Window takes a JPanel class as an arguments. In the given example has 2 components they are 1. JTextArea  2. JButton [Submit] which are appended to a JPanel.. The below image shows the effect before selecting the JForm: This image shown is the effect after selecting the JForm:                                       the below code is an example which i...

　 Swing toolkit provides a component called JColorChooser to choose colors. It allows users to select color from multiple color combinations. Some times our application may need simple component with an option to select only basic colors/ less number of color options unlike sepearate dialog with too may color options[JColorChooser]. This JColorComboBox may serve the need. I wanted my color chooser to behave like JComboBox. The popup shows all 12 colors and their names, among all of them one color can be choosen. see the below image. I created two classes          1. JColorComboBox          2. ColorRenderer JColorComboBox extends the JComboBox and ColorRenderer extends JLabel and implements ListCellRenderer. import java.awt.Color; import java.awt.Component; import java.awt.Font; import java.util.Enumeration; import java.util.Hashtable; import javax.swing.*; /** * * @author sharath */ public class JCol...

If you are interested in designing GUIs and building custom components with Swing toolkit, definitely Romain guy's blog  can be good reference for you, he writes about his work on swing components, custom components, tips and tricks on designing and using components. and you can download the demos of his work. You find more swing articles in 2005, 2006 archives. His URL: http://www.curious-creature.org/

Swing toolkit comes with few standard Layout Managers where none of them serves the need of arranging components in a way that usually developers require. some of them does, but it takes lot of coding time to achieve it. GridBagLayout is the most flexible layout manager available in swing toolkit but their are so many variables that developer has to look after. DesignGridLayout can be a useful LayoutManager to arrange components in less time with very small snippet of code and can still get proper alignment. Layouting with DesignGridLayout is as easy as coding with various GUI Builder tools available in varoius IDEs. Simple program which demonstrates DesignGridLayout: import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JSeparator; import javax.swing.JTextField; import javax.swing.SwingUtilities; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; import net.java.dev.designgr...