SetString() and Unicode to ASCII/ISO conversion

Question

Hi,
I encountered next problem. My database works in ISO-Latin-1 character set. Still, if I call PreparedStatement.setString(String arg) I would expect this call would convert arg parameter to ISO-Latin-1 using standard conversion mechanism. But after some testing I found out that instead of converting Java characters Oracle's driver just skips hi-byte. So if I have character with hex code 0x2019, which is absolutely normal unicode character. Oracle's driver converts it into 0x19 code, which is not even printable character and not valid ASCII code. Java's standard CharToByteConverter gives 0x63 ('?') code, which, at least, is valid ASCII/ISO-1 character.
And some soft reports "Invalid Character" errors encountering 0x19 and other such codes.
Here's a fragement from Oracle's JDBC log:
DBCV DBG2 UCS-2 bytes (10 bytes):
20 19 20 1c
DBCV FUNC DBConversion.stringToAsciiBytes(str)
DBCV DBG2 DBAccess bytes (5 bytes):
19 1c
Has anyone encountered this problem? Has anyone found work-around?
Checking and converting all strings before calls to setString() would be too overwhelming.
Thanks,
Dmitry

Answer 1

You may not store a string as ASCII values.
Any string you create is stored in Unicode.
The first 128 elements of Unicode are the same as ASCII.
If you want the ASCII representation of the letter "a", then:
System.out.println( java.lang.Character().getNumericValue( 'a' ) );
As DrClap said, there is no reason to save a string in ASCII format since it will be saved in unicode format and thus Java already knows what the ASCII values will be.
If you want to output a string in ASCII format, do it like this:
public Vector convert( String input ) {
StringBuffer tmpIn = new StringBuffer( input );
Vector tmpOut = new Vector
for ( int index = 0; index < tmpIn.length; index++ ) {
char tmpCharacter = tmpIn[ index ];
int tmpValue = java.lang.Character().getNumbericValue( tmpCharacter ) );
tmpOut.addElement( tmpValue );
return tmpOut;
And then display each element as you see fit.
Fixing the bugs in this code is an exercise for the reader. If you want to do something like this, you should be thinking about why you want to do this as well as how to do this.