ORA-14552: cannot perform a DDL, commit or rollback inside a query or DML

Cause:
=====
DML operations like create, drop etc. and rollback/commit can not be performed in a SQL statement

Example:
=======
The most general case where this error occurs is calling a function as
SELECT myFunc(.. .. ..) FROM dual..
Something like this or the like, Where myFunc contains DML operations, rollback or commit statements.

Solution:
==========
You have to ensure that DML operations and rollback/commit operations must be autonomous instead of inside a query.

For the case described above you can execute the function myFunc as
var:=myFunc(.. .. ..);

Or redefine the function as
CREATE OR REPLACE function myFunc(.. .. ..) RETURN ..
AS
....
....
PRAGMA AUTONOMOUS_TRANSACTION
begin
.....
.....
.....
end;

Java By Example: Java Calendar day, month, week, year, hour getting, java.util.Calendar

Java provides a strong way to work with date and calendar. Here is an example of java calendar to get values of --

* Month

* Year

* Week of year

* Week of month

* Day of month

* Hour

etc...

In this way we can also get some other information from calendar, like

* day of year

* Hour of day

* Minutes

* Seconds

* Time Zone

etc ..

import java.util.Calendar;

publicclass JavaCalendar {

publicstaticvoid main(String args[]){

Calendar calendar = Calendar.getInstance();

/* Setting calendar for current time */

calendar.setTimeInMillis(System.currentTimeMillis());

/* Get calendar month */

System.out.println(calendar.get(Calendar.MONTH)+1);

/* Get calendar year */

System.out.println(calendar.get(Calendar.YEAR

/* Get calendar week of year */

System.out.println(calendar.get(Calendar.WEEK_OF_YEAR

/* Get calendar week of month */

System.out.println(calendar.get(Calendar.WEEK_OF_MONTH

/* Get calendar day of week */

System.out.println(calendar.get(Calendar.DAY_OF_WEEK

/* Get calendar day of the month */

System.out.println(calendar.get(Calendar.DAY_OF_MONTH

/* Get calendar Hour */

System.out.println(calendar.get(Calendar.HOUR

}

}

Java By Example: Java Menue Example [ javax.swing.JMenu ]

Here is a very basic example of Java Menu[JMenue]

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

public class Menu extends JFrame{
public Menu()
{
super("Menu example");

JMenu file = new JMenu("File");
file.setMnemonic(’F’);
JMenuItem newItem = new JMenuItem("New");
newItem.setMnemonic(’N’);
file.add(newItem);
JMenuItem openItem = new JMenuItem("Open");
openItem.setMnemonic(’O’);
file.add(openItem);
JMenuItem exitItem = new JMenuItem("Exit");
exitItem.setMnemonic(’x’);
file.add(exitItem);

//adding action listener to menu items
newItem.addActionListener(
new ActionListener() {

public void actionPerformed(ActionEvent e)
{
System.out.println("New is pressed");
}
}
);
openItem.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e)
{
System.out.println("Open is pressed");
}
}
);
exitItem.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e)
{
System.out.println("Exit is pressed");
}
}
);
JMenuBar bar = new JMenuBar();
setJMenuBar(bar);
bar.add(file);

getContentPane();
setSize(400, 400);
setVisible(true);
}

public static void main(String[] args)
{
Menu app = new Menu();
app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Java Vector to array or List to array

We can easily get an array from Vector or List by just calling toArray() methods. This will generate arrays of Objects. Here is an example of getting array of Strings from java.util.Vector and java.util.List. I hope this will be helpful to you..

Vector friends = new Vector();
friends.add("Tuhin");
friends.add("Sumon");
friends.add("Habib");
friends.add("Shishir");
friends.add("Kiser");
friends.add("Zimi");
friends.add("Lizzie");

String arr[] = (String[]) friends.toArray(new String[0]);
System.out.println(Arrays.toString(arr));

List friendsList = new ArrayList();
friendsList.add("Tuhin");
friendsList.add("Sumon");
friendsList.add("Habib");
friendsList.add("Shishir");
friendsList.add("Kiser");
friendsList.add("Zimi");
friendsList.add("Lizzie");
arr = (String[]) friendsList.toArray(new String[0]);
System.out.println(Arrays.toString(arr));

If you execute the above code block. This will generate an output as follows..

[Tuhin, Sumon, Habib, Shishir, Kiser, Zimi, Lizzie]
[Tuhin, Sumon, Habib, Shishir, Kiser, Zimi, Lizzie]

Java Sorting Array, List

Java provides an interface java.util.Collections which provides way to sort List, Arraylist etc. We can sort an array of String by first transforming it to a List first then applying Collection.sort() method then again transforming from List to String array. Here is a practical example of this. Hope this will be helpful to you.

String friends[] = {"Tuhin", "Sumon","Habib","Shishir","Kiser","Zimi","Lizzie"};
System.out.println(Arrays.toString(friends));
List tempList = Arrays.asList(friends);
System.out.println(tempList);
Collections.sort(tempList);
System.out.println(tempList);
friends = (String[]) tempList.toArray(new String[0]);
System.out.println(Arrays.toString(friends));

This code block if execute will generate output like ...

[Tuhin, Sumon, Habib, Shishir, Kiser, Zimi, Lizzie]
[Tuhin, Sumon, Habib, Shishir, Kiser, Zimi, Lizzie]
[Habib, Kiser, Lizzie, Shishir, Sumon, Tuhin, Zimi]
[Habib, Kiser, Lizzie, Shishir, Sumon, Tuhin, Zimi]