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SQL Anywhere 10.0.1 » SQL Anywhere Server - Programming » Tutorial: Using Java in the Database » Special features of Java classes in the database

Special features of Java classes in the database Next Page

Calling the main method


You typically start Java applications (outside the database) by running the Java VM on a class that has a main method.

For example, the Invoice class in the file samples-dir\SQLAnywhere\JavaInvoice\Invoice.java has a main method. When you execute the class from the command line using a command such as the following, it is the main method that executes:

java Invoice
To call the main method of a class from SQL
  1. Declare the method with an array of strings as an argument:

    public static void main( java.lang.String args[] )
    {
    ...
    }
  2. Create a stored procedure that wraps this method.

    CREATE PROCEDURE JavaMain( in arg char(50) )
    EXTERNAL NAME 'JavaClass.main([Ljava/lang/String;)V'
    LANGUAGE JAVA;

    For more information, see CREATE PROCEDURE statement.

  3. Invoke the main method using the CALL statement.

    call JavaMain( 'Hello world' );

    Due to the limitations of the SQL language, only a single string can be passed.