Blackberry Development 4: Create an User Interface

January 27, 2012 1 Comment

There are three types of UI components from RIM API:

Screens (net.rim.device.api.ui.Screen): There’s one active screen per application at any time. Screens handle field layout through a delegate manager and provide additional functionality like menus.

Managers (net.rim.device.api.ui.Manager): These arrange fields on the screen. Each field must belong to one and only one manager. Each manager is also a field, meaning managers can contain other managers, allowing for some pretty intricate UI layouts.

Fields (net.rim.device.api.ui.Field): These are the basic building blocks of the UI. Generally, each control, such as a button or text field, corresponds to an instance of a field. The Field class draws the control and handles user input.

Please refer to Blackberry Smartphone UI Guide from RIM.

UiTest.java(Project: UiTest)

package com.henry416.UiTest;
import net.rim.device.api.ui.UiApplication;

public class UiTest extends UiApplication {
     public UiTest () {
        UiTestMainScreen mainScreen = new UiTestMainScreen();
        pushScreen(mainScreen);
     }

     public static void main(String[] args) {
        UiTest app = new UiTest();
        app.enterEventDispatcher();
     }
}

UiTestMainScreen.java:

package com.henry416.UiTest;
import net.rim.device.api.ui
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.component.BitmapField;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.component.EditField;
import net.rim.device.api.ui.component.PasswordEditField;
import net.rim.device.api.ui.component.CheckboxField;
import net.rim.device.api.ui.component.ObjectChoiceField;
import net.rim.device.api.ui.component.ButtonField;
import net.rim.device.api.ui.container.HorizontalFieldManager;
import net.rim.device.api.ui.container.HorizontalFieldManager;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.component.Dialog;
public class UiTestMainScreen extends MainScreen implements FieldChangeListener {
    BitmapField bitmapField;
    EditField usernameField;
    PasswordEditField passwordField;
    ObjectChoiceField domainField;
    CheckboxField rememberCheckbox;
    ButtonField clearButton;
    ButtonField loginButton;
    public UiTestMainScreen() {
         // add a logo at top, also put it under rsc folder of the project
         Bitmap logoBitmap = Bitmap.getBitmapResource("UiTest_logo.png");
         bitmapField = new BitmapField(logoBitmap, Field.FIELD_HCENTER);
         add(bitmapField);
         add(new SeparatorField());
         add(new LabelField("Please enter your credentials:"));
         // add two fields
         usernameField = new EditField("Username:", "");
         passwordField = new PasswordEditField("Password:", "");
         add(usernameField);
         add(passwordField);
         // add a domain field
         domainField = new ObjectChoiceField("Domain:", new String[] {"Prod", "Dev"});
         add(domainField);
         // add a checkbox
         rememberCheckbox = new CheckboxField("Remember password", false);
         add(rememberCheckbox);
         add(new SeparatorField());
         // create two buttons
         clearButton = new ButtonField("Clear", ButtonField.CONSUME_CLICK);
         loginButton = new ButtonField("Login", ButtonField.CONSUME_CLICK);
         // using HorizontalFieldManager to add two buttons
         HorizontalFieldManager buttonManager = new HorizontalFieldManager(Field.FIELD_RIGHT);
         buttonManager.add(clearButton);
         buttonManager.add(loginButton);
         add(buttonManager);
         // hook the events
         clearButton.setChangeListener(this);
         loginButton.setChangeListener(this);
    }
    public void fieldChanged(Field field, int context) {
       if (field == clearButton) {
          clearTextFields();
          //Dialog.inform("Clear Button Pressed!");
       }
       else if (field == loginButton) {
            login();
            }
    }
    private void clearTextFields() {
        usernameField.setText("");
        passwordField.setText("");
    }
    private void login() {
         if (usernameField.getTextLength() == 0 || passwordField.getTextLength() == 0) {
            Dialog.alert("You must enter a username and password");
         }
         else {
            String username = usernameField.getText();
            String selectedDomain =
               (String)domainField.getChoice(domainField.getSelectedIndex());
            LoginSuccessScreen loginSuccessScreen =
                new LoginSuccessScreen(username, selectedDomain);
             UiApplication.getUiApplication().pushScreen(loginSuccessScreen);
         }
     }
}

LoginSuccessScreen.java

package com.henry416.UiTest;

import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.container.MainScreen;

public class LoginSuccessScreen extends MainScreen {
    public LoginSuccessScreen(String username, String domain) {
        add(new LabelField("Logged in!"));
        add(new LabelField("Username: " + username));
        add(new LabelField("Domain: " + domain));
    }
}

Filed under Blackberry, Java, Mobile, Projects

Blackberry Development 3: Single Threading and Event Testing

January 27, 2012 Leave a comment

The BlackBerry UI API is single threaded. This means that all UI updates and events are handled by the same thread—or more precisely, they must be handled while holding the event lock, which most of the time is held by the UI thread.

First, let’s change labelFieldto be a member variable instead of a variable local to the constructor, and add a method to append text to it:

public class HelloWorldMainScreen extends MainScreen {

    private LabelField labelField;

    public HelloWorldMainScreen() {
        labelField = new LabelField("Hello World");
        add(labelField);
    }

    public void appendLabelText(String text) {
        labelField.setText(labelField.getText() + "\n" + text);
    }

}

Because appendLabelText calls LabelField.setText, the call can only be made from the event thread. If you attempt to call this method directly from another thread, an exception will be thrown.

Now, we’ll define the thread class that will actually do the testing. It will loop from 1 to 10. In each iteration, it will wait 5 seconds and then add some text to the LabelField. Create a new class called MainScreenUpdaterThread that extends java.lang.Thread. The full source code follows:

package com.henry416;

import net.rim.device.api.ui.UiApplication;

public class MainScreenUpdaterThread extends Thread {
    HelloWorldMainScreen mainScreen;

    public MainScreenUpdaterThread(HelloWorldMainScreen mainScreen) {
        this.mainScreen = mainScreen;
    }

    public void run() {
        for (int i = 0; i < 10; i++) {

            try {
                 Thread.sleep(5000);
            } catch (InterruptedException ex) {

            }
            // Queue a new task on the event thread
            UiApplication.getUiApplication().invokeLater(new Runnable() {
                 public void run() {
                    mainScreen.appendLabelText("Testing");
                 }

            });

        }
     }
}

To actually update the UI, we’re using an anonymous inner class, which is a class that we define at the point where we instantiate it. Our anonymous inner class calls the one method that needs to be called on the event thread: appendLabelText (which calls LabelField.setText).

We’ll start our thread in the HelloWorldMainScreen constructor as follows:

    public HelloWorldMainScreen() {
        labelField = new LabelField("Hello World");

        add(labelField);

        MainScreenUpdaterThread thread = new MainScreenUpdaterThread(this);
        thread.start();
    }

Finally, running this application will produce the following results:

HelloWorld
Testing
Testing
Testing
Testing
Testing

Try to modify the above method with the following method:

    public void run() {
        for (int i = 0; i < 10; i++) {
            try {
                Thread.sleep(5000);
            } catch (InterruptedException ex) {

            }
            // Ensure we have the event lock
            synchronized(UiApplication.getEventLock()) {
                mainScreen.appendLabelText("Testing Again");
            }
        }
    }

Filed under Blackberry, Java, Microsoft Windows, Mobile, Projects

Blackberry Development 2: Steps for an app

January 26, 2012 1 Comment

A step guide for a simple app development by using Eclipse and Blackberry Plug-In. This is the follow up of my previous post Blackberry Development 1: setup environment.

2.1. create a project in Eclipse

To create a new BlackBerry project, click the File menu, and choose New Image from book BlackBerry Project. Name your project HelloWorld, and click Finish.

What is created?

The IDE will create the following:

  • src folder: Where all our source files will reside
  • res folder: Where all resource files (i.e., images) will reside
  • JRE System Library: The BlackBerry runtime library containing the BlackBerry API (by default, it is OS 7)
  • BlackBerry_App_Descriptor.xml file: A file where you can configure your application, including the name of the application and the icon your application will use

 2.2. Create a main application class

Right-click the HelloWorld project icon in the Package Explorer, and from the pop-up menu, select New Image from bookClass. In the dialog, type the following values:

  • Package: com.henry416
  • Name: HelloWorldTest (you can leave off the .java file extension)
  • Superclass: net.rim.device.api.ui.UiApplication
  •  
 What is created?

The application class is created and performs the following:

  • Create an instance of the application

  • Create the main screen and push it onto the display stack

  • Start the event dispatch thread

package com.henry416;

import net.rim.device.api.ui.UiApplication;

public class HelloWorldTest extends UiApplication {

    public HelloWorldTest() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

    }

}

2.3. Create a main screen class

Click New Image from book Class again (or right-click the package in the tree view and select New Image from bookClass, and you won’t have to reenter the package name). Fill in the following values:

  • Package: com.henry416

  • Name: HelloWorldMainScreen

  • Superclass: net.rim.device.api.ui.container.MainScreen (or type MainS, and press Ctrl+spacebar)

 What is created?
package com.henry416;

import net.rim.device.api.ui.container.MainScreen;

public class HelloWorldMainScreen extends MainScreen {

}

2.4. Add code to the Hello World Classes

Go back to HelloWorldTest, our main class. Fill in the constructor of HelloWorldApp. This will create the main screen and push it onto the display stack:

class HelloWorldTest extends UiApplication {
    HelloWorldTest() {
        HelloWorldMainScreen mainScreen = new HelloWorldMainScreen();
        pushScreen(mainScreen);
    }
}

The main method will create an instance of our application and start the event dispatcher, which is the mechanism that does all the drawing to the screen, and listens for all user interaction for our application.

class HelloWorldTest extends UiApplication {
   …
    public static void main(String[] args) {
        HelloWorldTest app = new HelloWorldApp();
        app.enterEventDispatcher();
    }
}

The enterEventDispatcher method will never return as long as the application is running. Essentially, the thread that entered the main application becomes the event dispatch thread. We’ll explore this in greater depth later, but for now, just remember that the method won’t return during the application’s normal life cycle.

2.5. Code the Main Screen Classes

Add some GUI components to our main screen class with the following code for HelloWorldMainScreen.java:

public class HelloWorldMainScreen extends MainScreen {
    public HelloWorldMainScreen() {
        net.rim.device.api.ui.component.LabelField labelField = new
net.rim.device.api.ui.component.LabelField("Hello World");

        add(labelField);
    }
}

Note that we subclass MainScreen instead of Screen because MainScreen gives us a couple of things automatically—namely a basic layout manager (to position our UI controls on the screen) and a default menu.  

2.6. Test the app in the simulator

Click the arrow next to the debug icon on the Eclipse toolbar, and select Debug Configurations. Each configuration can have different debug parameters, and as you develop applications, you’ll likely end up with a few different configurations for debugging different OS versions, screen sizes, and so on.

Select the BlackBerry Simulator icon on the left side, and click the New button on the toolbar in the dialog window.

On the Project tab, check the newly created HelloWorld project. Then click the Debug button at the bottom of the dialog. The simulator will launch with your application deployed.

After you click the Debug button, the simulator will start up. When it is finished, you will see your HelloWorldTest on the BlackBerry simulator home screen,

Click the app icon to test…

Filed under Blackberry, Java, Microsoft Windows, Mobile, Projects

Blackberry Development 1: setup environment

January 26, 2012 1 Comment

Assumption: Windows XP SP3 onward and Blackberry Desktop Software (from the CD with your phone or installed from RIM website)

1. Download and Install

1.1. Java SE JDK

Install it from www.oracle.com/technetwork/java/index.html if not installed.

1.2. Eclipse and BlackBerry JDE Plug-in for Eclipse

There are two BlackBerry development environments produced by RIM: the BlackBerry Java Development Environment (JDE) and the BlackBerry JDE Plug-in for Eclipse.

To use Eclipse to develop for BlackBerry, you’ll need to download Eclipse IDE. However, to make things simple for you, RIM has bundled Eclipse 3.6 (Helios) with the BlackBerry JDE Plug-in with BlackBerry SDK 7.0. You can download the BlackBerry Java Plug-in for Eclipse at http://us.blackberry.com/developers/javaappdev/devtools.jsp.

I already have Eclipse installed, and the following steps are used to download and install the Blackberry Plug-In onto Eclipse:

  • Select Help Menu.
  • From the menu, select the Install New Software menu item. The Install New Software screen will appear.
  • From the Install New Software screen, click the Add button.
  • Paste http://www.blackberry.com/go/eclipseUpdate/3.6/java into the location text box, give it the name “text box,” and click OK .
  • Select the BlackBerry Java Plug-in item and at least one BlackBerry Component Pack item that you want to work.
  • Then follow the onscreen instruction to finish installation. You will have to restart Eclipse IDE in order for the installation to take effect.
1.3. Additional Simulators

In addition to the simulators that are available to you in the BlackBerry Java Plug-in for Eclipse, RIM provides many simulators that are very useful for testing how your application functions with different screen resolutions or input methods. The simulators can be downloaded from the Developer Zone, at http://na.blackberry.com/eng/developers/resources/simulators.jsp

1.4. Code Signing Key

Please register for the code signing keys at http://na.blackberry.com/eng/developers/javaappdev/codekeys.jsp.

The online application form for signing keys is available at https://www.blackberry.com/SignedKeys/

To install your code signing keys in Eclipse with the BlackBerry JDE plug-in, simply import the keys by doing the following:

  • From Eclipse IDE, select Windows from the menu, and then choose Open Perspective Image from book Others.

  • Select the BlackBerry Application Development perspective.
  • Then from the menu, select BlackBerry Image from book Sign Image from book Install New Key. You’ll be prompted to create a new public/private key pair.
  • Click Yes on this dialog, and you’ll be asked for a private key password to protect your key file. Remember this password—you’ll be asked for it every time you want to sign your application. You’ll then be asked to generate some random data by moving your mouse pointer around to increase the radomized calculation.
  • After this, you’ll be asked to enter the PIN you provided when you applied for your keys and the private key password you just entered.
  • For the next two keys, you’ll already have generated your key pair, so you’ll just have to enter the PIN and private key password.

    Once you’ve created your key pair and installed your three keys, the key information is stored in three files:

         sigtool.csk
     sigtool.db
     sigtool.set

    The location of these files is <eclipse_directory>\plugins\net.rim.ejde\vmTools\, where <eclipse_directory> is where you installed your Eclipse environment (i.e., C:\Eclipse\plugins\net.rim.ejde\vmTools\).

    It’s also a very good idea to keep a backup of these files and your original key files if you ever have to rebuild your development environment

From now on, the development environment is ready.

Filed under Blackberry, Java, Projects Tagged with ,

Query Database Using Swing UI

January 12, 2012 1 Comment

SimpleForm.java

Query DB on A Swing Form

DoConnect(): connect to db, run query, get first record into UI

BtnAction(): logic to manipulate the records (NEXT, PRVIOUS, FIRST, LAST)

Rest of codes (SWING UI) are generated by using NeatBean IDE 6.8 on Linux.

/*
 to compile: javac -cp /usr/share/java/postgresql.jar SimpleForm.java
 to execute: java -cp /usr/share/java/postgresql.jar:. SimpleForm
*/
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSet;
import javax.swing.JOptionPane;

public class SimpleForm extends javax.swing.JFrame {
    Connection con;
    Statement stmt;
    ResultSet rs;

    /** Creates new form SimpleForm */
    public SimpleForm() {
        initComponents();
        DoConnect();
    }

    public void DoConnect( ) {
        try {
            //connect to the database
            con = DriverManager.getConnection("jdbc:postgresql:mydb",
                    "testuser","testpassword");
            // construct a sql statement, execute it and load resultset to rs                                    "logan","ready2go");
            //stmt = con.createStatement();
            stmt = con.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE );
            String sql = "select firstname, lastname, name from employees, departments where employees.department = departments.id";
            rs = stmt.executeQuery(sql);
            // retrieve the fields from rs to txtFields
            if (rs.next()) {
               txtFirst.setText(rs.getString("firstname"));
               txtLast.setText(rs.getString("lastname"));
               txtDept.setText(rs.getString("name"));
            }
            else { JOptionPane.showMessageDialog(SimpleForm.this, "No records!");}
        }
        catch (SQLException err) {
            JOptionPane.showMessageDialog(SimpleForm.this, err.getMessage());
        }
    }
    // Next, Previous, First, Last Action Event Handlers
    public void DoBtnAction(int BtnAction ) {
    try {
         if (rs != null)
         {
          boolean Action = false;
          switch (BtnAction) {
            case 1:  Action = rs.next();
                     break;
            case 2:  Action = rs.previous();
                     break;
            case 3:  Action = rs.first();
                     break;
            case 4:  Action = rs.last();
                     break;
            default:
                     break;
            }
          if ( Action ) {
            txtFirst.setText(rs.getString("firstname"));
            txtLast.setText(rs.getString("lastname"));
            txtDept.setText(rs.getString("name"));
                        }
          else {
          switch (BtnAction) {
            case 1:  rs.previous( );
                     JOptionPane.showMessageDialog(SimpleForm.this, "End of File");
                     break;
            case 2:  rs.next( );
                     JOptionPane.showMessageDialog(SimpleForm.this, "Start of File");
                     break;
            default:
                     break;
                             }
              } // end of else for Action
             } // if Action
         else { JOptionPane.showMessageDialog(SimpleForm.this, "No records!");}
        } // try
    catch (SQLException err) {
            JOptionPane.showMessageDialog(SimpleForm.this, err.getMessage());
        }    
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        txtFirst = new javax.swing.JTextField();
        txtLast = new javax.swing.JTextField();
        txtDept = new javax.swing.JTextField();
        lblFirst = new javax.swing.JLabel();
        lblLast = new javax.swing.JLabel();
        lblDept = new javax.swing.JLabel();
        btnNext = new javax.swing.JButton();
        btnPrevious = new javax.swing.JButton();
        btnFirst = new javax.swing.JButton();
        btnLast = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        lblFirst.setText("First Name:");

        lblLast.setText("Last Name");

        lblDept.setText("Department:");

        btnNext.setText("Next");
        btnNext.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnNextActionPerformed(evt);
            }
        });

        btnPrevious.setText("Previous");
        btnPrevious.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnPreviousActionPerformed(evt);
            }
        });

        btnFirst.setText("First");
        btnFirst.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnFirstActionPerformed(evt);
            }
        });

        btnLast.setText("Last");
        btnLast.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnLastActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(49, 49, 49)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(btnPrevious)
                        .addGap(18, 18, 18)
                        .addComponent(btnNext)
                        .addGap(46, 46, 46)
                        .addComponent(btnFirst)
                        .addGap(18, 18, 18)
                        .addComponent(btnLast)
                        .addContainerGap())
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(lblDept)
                            .addContainerGap())
                        .addGroup(layout.createSequentialGroup()
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                                .addComponent(txtDept, javax.swing.GroupLayout.DEFAULT_SIZE, 323, Short.MAX_VALUE)
                                .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                        .addComponent(txtFirst, javax.swing.GroupLayout.PREFERRED_SIZE, 126, javax.swing.GroupLayout.PREFERRED_SIZE)
                                        .addComponent(lblFirst))
                                    .addGap(42, 42, 42)
                                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                        .addComponent(lblLast)
                                        .addComponent(txtLast, javax.swing.GroupLayout.PREFERRED_SIZE, 129, javax.swing.GroupLayout.PREFERRED_SIZE))))
                            .addContainerGap(81, Short.MAX_VALUE)))))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(27, 27, 27)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(lblFirst)
                    .addComponent(lblLast))
                .addGap(27, 27, 27)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(txtLast, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(txtFirst, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(22, 22, 22)
                .addComponent(lblDept)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(txtDept, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(32, 32, 32)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(btnPrevious)
                    .addComponent(btnLast)
                    .addComponent(btnFirst)
                    .addComponent(btnNext))
                .addContainerGap(58, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>

    private void btnNextActionPerformed(java.awt.event.ActionEvent evt) {
        DoBtnAction(1);
    }

    private void btnPreviousActionPerformed(java.awt.event.ActionEvent evt) {
        DoBtnAction(2);
    }

    private void btnFirstActionPerformed(java.awt.event.ActionEvent evt) {
        DoBtnAction(3);
    }

    private void btnLastActionPerformed(java.awt.event.ActionEvent evt) {
        DoBtnAction(4);
    }

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new SimpleForm().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JButton btnFirst;
    private javax.swing.JButton btnLast;
    private javax.swing.JButton btnNext;
    private javax.swing.JButton btnPrevious;
    private javax.swing.JLabel lblDept;
    private javax.swing.JLabel lblFirst;
    private javax.swing.JLabel lblLast;
    private javax.swing.JTextField txtDept;
    private javax.swing.JTextField txtFirst;
    private javax.swing.JTextField txtLast;
    // End of variables declaration

}

Filed under Databases, Java, PostgreSQL Tagged with , , , , ,

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