MySQL Varchar not matching Java String

Question

I am using MySQL 4.0.16 with jdk1.3.1_01 and I have a strange occurance going on with comparing Strings from the mysql database with Strings entered from java, coming from a JTextField. The mysql field in question was created like this:-
CREATE TABLE hardware (
serialnumber VARCHAR(20) UNIQUE NOT NULL,
.....The line in arrows on the proceeding code is where I am having problems. I changed the method from .getString() to getInt() to test the IF statement and matches were produced as expected but with getString(), no matches are made from this line even though 'System.out' shows the variable from mysql and the variable from java (a JTextField) are both the same at the point of the IF statement, (as tested by the line below the arrows.
rs = stmt.executeQuery("select count(*)from hardware;");
rs.next();for (int x=0;x < rowSize; x++) {
   rs.next();
  if (rs.getString(1) == newSerialNumber) {    // <<<<<<<<
          nonUniqueSerialNumber=true;
  System.out.println("loop on "+x+"rs.getString(1) is "+rs.getString(1)+" java textfield is "+newSerialNumber);
rs.close();
// If reached this stage - the Serial Number is OK.
int rowSize = rs.getInt(1);
rs = stmt.executeQuery(getAllSerialNumbers_QRY);Any known reasons or thoughts greatly appreciated? I've looked through the mysql manual with no mention of VARCHAR or CHAR incompatibilites. Also I am using the Connector/J 3.0.9 JDBC driver..
Pat Rivet

Answer 1

Nothing to do with the database, just a common newbie-to-Java error. Don't use == to compare the contents of two String objects, use the equals() method instead. Like this:if (rs.getString(1).equals(newSerialNumber))...