using clearParameter() even thought PreparedStatement is being closed - sql

Question

private PreparedStatement InsertPS = null;
public boolean InsertInDB(String username, String password, double balance, String secret) {
boolean ans = false;
try {
InsertPS = con.prepareStatement("Insert into BankDB values(?,?,?,?)");
String data[] = AMC.SendtoDB(password, secret);
InsertPS.setString(1, data[0]);
InsertPS.setString(2, username);
InsertPS.setString(3, data[1]);
InsertPS.setDouble(4, balance);
int rows = InsertPS.executeUpdate();
if (rows != 0) {
ans = true;
}
InsertPS.clearParameters();
} catch (SQLException sqlInite) {
System.out.println("SQL Error in InsertInDB method: " + sqlInite);
} finally {
try {
InsertPS.close();
} catch (SQLException sqle) {
System.out.println("SQL Exception in InsertInDB method finally clause : " + sqle);
}
}
return ans;
}
Above is the InsertInDB() method given,
It has a InsertPS PreparedStatement Object.
Here is it necessary to use clearParameters() method even though i am closing the InsertPS object at the end of the method.
(I have provided a separate method to close the connection object)
also another question: Is it a good idea to create PreparedStatement Object's outside any method within a class,initializing using Constructor and Say for example Once all Object's (each in different method) are used, close all PreparedStatement Objects using a separate method.
public class JavatoDB {
Driver DM = null;
Connection con = null;
PreparedStatement InsertPS = null;
PreparedStatement BalancePS = null;
PreparedStatement DeletePS = null;
PreparedStatement UpdatePS = null;
PreparedStatement SearchDB = null;
ResultSet RS = null;
ResultSetMetaData RSMD = null;
AdminControl AMC = null;
public JavatoDB() {
AMC = new AdminControl();
try {
DM = new com.mysql.jdbc.Driver();
con = DriverManager.getConnection("jdbc:mysql://localhost/javadb", "java", "javaaccess");
InsertPS = con.prepareStatement("Insert into BankDB values(?,?,?,?)");
BalancePS = con.prepareStatement("Select BALANCE from BankDB where ACCNAME=? AND ACCPIN = ?");
DeletePS = con.prepareStatement("Delete from BankDB where ACCNAME = ? AND ACCPIN = ? ");
UpdatePS = con.prepareStatement("Update BankDB set BALANCE = (BALANCE + ?) where ACCNAME = ? AND ACCPIN = ?");
SearchDB = con.prepareStatement("Select ID AND ACCPIN from BankDB where ACCNAME = ? ");
} catch (SQLException JavatoDBContrsuctor) {
System.out.println("SQL Error in JavatoDBConstructor: " + JavatoDBContrsuctor);
}
}
public boolean InsertInDB(String username, String password, double balance, String secret) {
boolean ans = false;
try {
String data[] = AMC.SendtoDB(password, secret);
InsertPS.setString(1, data[0]);
InsertPS.setString(2, username);
InsertPS.setString(3, data[1]);
InsertPS.setDouble(4, balance);
int rows = InsertPS.executeUpdate();
if (rows != 0) {
ans = true;
}
InsertPS.clearParameters();
} catch (SQLException sqlInite) {
System.out.println("SQL Error in InsertInDB method: " + sqlInite);
}
return ans;
}
Suggestion's or Criticism on other aspects of code are also welcome.

Answer 1

For the first question, when you call:
con.prepareStatement()
a new preparedStatement is created, then parameters dont survive, i mean you dont need to clear then.
About the second question, in your implementation i cant see where you close your preparedStatement, and if you only add close, next time method will fail. Then, it is usual to create the preparedStatement and close it in the same method.