Skip to main content

Using JTable

JTable is the component which helps us to display the multi columned data. This post is about fetching database data and displaying it using JTable.
First we will design our Frame
public class MyFrame extends JFrame
{
 private JTable table;
 private JScrollPane jsp;
 public MyFrame()
 {
  super("MyFrame");
  setSize(400,400);
  setDefaultCloseOperation(EXIT_ON_CLOSE);
  setLocationRelativeTo(null);
  initMyFrame();
  setVisible(true);
 }
 private void initMyFrame()
 {
  setLayout(new BorderLayout());
  table=new JTable();
  jsp=new JScrollPane(table);
  add(jsp,BorderLayout.CENTER);


  // database connection and remaining code will go here
 }
 public static void main(String args[])
 {
  new MyFrame();
 }
}



Now we are ready with our frame which contains JTable, but our table does not contains any data.
So we need to establish the database connection, for this I am using PostgreSQL as backend.
Following code is for connecting to database
try
{
 Class.forName("org.postgresql.Driver");
 Connection con=DriverManager.getConnection("jdbc:postgresql://localhost:5432/mydatabase","postgres","postgres");
}catch(Exception e)
{
 System.out.println("Failed to connect to database");
 e.printStackTrace();
}
Now we have established the database connection and its time to fetch data from database and add it to our JTable
try
{
 Statement statement=con.createStatement();
 ResultSet rs=statement.executeQuery("select * from mytable");


 Vector cols=new Vector();
 cols.add("Id");
 cols.add("Name");


 Vector data=new Vector();
  while(rs.next())
  {
   Vector v=new Vector();
   v.add(rs.getInt(1));
   v.add(rs.getString(2));
   data.add(v);
  }


 table.setModel(new DefaultTableModel(data,cols));
 table.addNotify();
}catch(Exception e)
{
 e.printStackTrace();
}
In above code as we are using dynamic data for JTable so we are using Vectors, while using Vector first vector
Vector cols=new Vector();
This vector is for the headers which will be displayed in JTable, it can contain only Strings and the second vector
Vector data=new Vector();
Its for data in JTable which can contains collection only not just Strings, and that is the reason why we are adding Vector v to this data vector.
DefaultTableModel is the default table model provided by Java for setting new table model to JTable.
Method addNotify is important while adding or removing data from TableModel, it tells JTable that data has been modified and its time to refresh.

Comments

Popular posts from this blog

Spring AOP : JDK Proxy vs CGLib Proxy

Spring framework is one of the most widely used framework in Enterprise application development. It has so many features such as Dependency injection, Data access integration, MVC, AOP which takes care of most of the boilerplate part of project, and developers can then focus on business logic only.

One of the important feature in Spring is AOP. It is used by almost every enterprise application which is being developed using Spring.

AOP So what is AOP? Definition of AOP -
Aspect oriented programming is a programming paradigm which aims to increase modularity by allowing the separation of cross cutting concerns. Well, my understanding of AOP is - AOP allows us to introduce/join new modules in your project at pre-specified dynamic locations without having to code for it. Traditional examples of AOP is Transaction management, logging etc. You can read more about AOP at here.

This article is for those who know AOP, have used AOP in their projects but do not know how Spring or other DI fra…

Java Tools Plugin for Notepad++

This post and the plugin is outdated. Please use plugin from this link which is updated and allows customization of shortcut key mappings and much more.
Notepad++ is a great free editor. I like notepad++ because its a light weight editor and loads instantly. I use notepad++ for editing many files everyday. One plugin I always wanted was a plugin which lets me compile my java files and execute them from editor itself, but I couldn't find it so I wrote a myself. This plugin can be downloaded from this link.
I am working on this plugin to make it more effective, so that if user have more than one installations of JDK or JRE then user should be able to choose which one to use etc.
This is a simple plugin which has two commands-
Compile - compiles a java file.
Run - executes a java file.
For using this plugin Java must be installed on the system.

Notepad++ Compile and Run Java Programs

Notepad++ is a great file editor. It has many features. The most important feature which I like about Notepad++ is its light weight. It loads up so quickly, that's great. It also provides syntax highlighting for many languages. I use notepad++ to edit general files as well as my simple Java programs.
Although notepad++ provides functionality to run external programs, I prefer NppJavaTools plugin to compile and run Java programs using notepad++.
You can download NppJavaTools plugin from this page - NppJavaTools.

Installation
Installation of plugins in notepad++ is very simple process. All you have to do is copy plugin dll into plugins folder of notepad++ installation directory and restart the notepad++.

Features
This plugin provides following features,


Compile and run your Java files within Notepad++Set custom hotkeys for compiling and running Java CodeLibrary support Compile and RunThis function allows you to run your Java programs to compile and run from Notepad++. Set Custom hotkeysThi…