Problems with execute query with JDBC

[Alfred Pimminger]

I've written an JDBC interface.
Works fine when i read data from the mysql database.

But when I want to write something I got this error message:
"java.sql.SQLException: Can not issue data manipulation statements with executeQuery()"

here is the javasnippte with which I've tried this:
......
try{
resultSet = statement.executeQuery(query);
}catch (SQLException ex){
switch(ex.getErrorCode()){
case 1062:SystemMessage.print("Dataset already exists",
"JDBCAdapter.writeSqlStatement");
ErrorCode = 2;
break;
default:SystemMessage.print("Error/Warning during execution"+
"\r\n ErrorCode: " +
String.valueOf(ex.getErrorCode()) +
"\r\n ErrorMessage: " +
ex.toString(),
"JDBCAdapter.writeSqlStatement");
ErrorCode = -1;
}
}
.....

This snippet had worked 2 years ago ... now I wanted to program new things.. but what should i program when even the old snippet are not working.
I thought of an error with the login permission ... but this can't be the problem because I'm able to read ... and I set all the parameter of the user to 'Y'
Has anyone a suggestion?
I got stuck because of this problem.