I'm trying to work through creating a very simple class to send queries to an instance of Oracle XE 11g, essentially making a very simple SQL*Plus to get the basics of JDBC down.
The source code I'm currently working with is:
public class Example {
static String username, password;
static String dbDriver = "oracle.jdbc.driver.OracleDriver";
static String dbConnection = "jdbc:oracle:thin:@//localhost:1521/xe";
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String line;
Connection c = null;
Statement stmt = null;
int loginAttempts = 0;
// Log in loop
do {
try {
Class.forName(dbDriver);
System.out.print("Enter username: ");
line = input.nextLine();
if (line.contains("/")) {
String[] login = line.split("/");
if (login.length != 2) {
System.out
.println("Unrecognized information, exiting...");
System.exit(0);
}
username = login[0].trim();
password = login[1].trim();
} else {
username = line;
System.out.print("Enter password: ");
password = input.nextLine();
}
c = DriverManager.getConnection(dbConnection, username,
password);
stmt = c.createStatement();
loginAttempts = -1;
} catch (ClassNotFoundException e) {
System.err.println("Unable to connect to database, exiting...");
System.exit(-1);
} catch (SQLException e) {
System.out.println("Username and/or password is incorrect");
if (++loginAttempts == 1) {
System.out.println("Too many failed login attempts, exiting...");
System.exit(0);
}
}
} while (loginAttempts != -1);
// Input loop
for (;;) {
try {
// Write out the prompt text and wait for input
if(c == null) {
throw new IllegalStateException("Connection should not be null");
}
System.out.print(c.getSchema() + ":> ");
String tmp = input.nextLine();
// Check if the user entered "exit"
if (tmp.toLowerCase().equals("exit")) {
System.out.println("Exiting...");
input.close();
System.exit(0);
}
String query;
// TODO: For some reason, no semi-colon is allowed
if (tmp.charAt(tmp.length() - 1) == ';')
query = tmp.split(";")[0];
else
query = tmp;
// System.out.println(query);
ResultSet rset = stmt.executeQuery(query);
ResultSetMetaData rmd = rset.getMetaData();
int colCount = rmd.getColumnCount();
// Column indices start with 1, print column names
for (int i = 1; i <= colCount; i++) {
System.out.printf("%-20.20s ", rmd.getColumnName(i));
}
System.out.println();
while (rset.next()) {
for (int i = 0; i < colCount; i++) {
System.out.printf("%-20.20s | ", rset.getString(i + 1));
}
System.out.println();
}
System.out.println();
} catch (SQLSyntaxErrorException e) {
System.out.println("Encountered a syntax error:\n"
+ e.getMessage());
} catch (SQLException e) {
System.err.println("An unexpected error occurred");
e.printStackTrace();
input.close();
System.exit(-1);
}
}
}
}
In the second try/catch block, in the for(;;) loop, I get the following output:
Enter username: hr/hr
Exception in thread "main" java.lang.AbstractMethodError: oracle.jdbc.driver.T4CConnection.getSchema()Ljava/lang/String;
at jdbctest.Example.main(Example.java:69)
I checked out the Oracle docs (java.lang.AbstractMethodError), and it says that this error can only be thrown if:
"the definition of some class has incompatibly changed since the currently executing method was last compiled."
I'm thinking that there's something I'm missing with line 27, but I'm not sure how to approach this problem and any guidance would be extremely helpful.
