This morning I was going through an article try-catch-finally (TCF) in Java.
Suddenly got some weird thoughts.

Plugged myself to Eclipse to dive into the right answers. Here are few bullets:

1. Can try exist all alone ( without catch, without finally) ?
ANS: try block {1} i.e 1 time
catch block * i.e 0 or N times
finally block ? i.e 0 or 1 time

2. Can I put just try block in an “if” condition leaving catch block independent?

if(alive){
  try{
         //dive into pacific ocean once more
      {
} // end of if
catch(Exception e) {
     // Reported dead before entering to pacific
}

ANS: No. You cant associate catch without if.

3. I want to write the below JDBC scenario in below manner:

try block -> Establish a connection to the database & submit a query to the MySQL database for execution
catch block -> If connection failure or query failure happens, will give a message to the end user.
finally block -> close the database connection at any cost

Not a big deal, my code is ready. Here I go………

public class TtryCatchFinallyDemo {

	public static void main(String[] args) {
		Connection con = null;
		Statement stmt = null;
		ResultSet rs = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			con = DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql", "root", "password");
			stmt = con.createStatement();
			rs = stmt.executeQuery("Select * FROM user");
			while (rs.next()) {
				System.out.println(rs.getString("User2")); //Mistaken purposely- User2 instead "User" // PlaceHolder_00
			}
			con.close(); // PlaceHolder_01
		}
		catch (Exception e) {
			System.out.println("Exception Occurred :- " + e.getMessage());
			// PlaceHolder_02
		}finally{
                         con.close; // PlaceHolder_03
			}
		}
	}
}

Looks absolutely fine. Right?

No. It has error.
Exception in thread “main” java.lang.Error: Unresolved compilation problem:
Unhandled exception type SQLException

Assume the error happens at PlaceHolder_00, control will move to the exception block and then finally block.

Writing con.close() at PlaceHolder_01 will not close the database connection. Thus I need to close it at finally block at PlaceHolder_03.
But will it serve my purpose?

Thus the correct way of doing it would be

Modify the above code to

finally{
			try{
				System.out.println(con.isClosed());  // false
				con.close();
				System.out.println(con.isClosed()); // true
				con = null;
			}catch(Exception e){// PlaceHolder_03
			     System.out.println("Exception occurred!");
			}
		}

But again re-writing try catch withing finally wont be a good idea.

Hopefully setting the con to null will solve everything.

finally{
   con = null;
}