26-1.

Oracle8i’s Java Virtual Machine is called:

26-2.

True or false?

26-3.

Java programs that are compiled and stored in the database are called:

26-4.

PL/SQL procedures and functions are most similar to Java:

26-5.

What kind of file is created when you compile a Java program?

26-6.

Which of the following establishes a logical correspondence between a Java method and a PL/SQL procedure or function (standalone or packaged) or a member method of a SQL object type:

26-7.

Consider the following Java program:

public class xxx {
   public static void doit () {
       System.out.println("Hello World!!!");
   }
}

The missing element (denoted by xxx) is the:

26-8.

Consider the following Java program:

public class helloWorld {
   public static void xxx () {
       System.out.println("Hello World!!!");
   }
}

The missing element (denoted by xxx) is the:

26-9.

Consider the following Java program:

public class simpleJava {
  public static void printIt (xxx s) {
     System.out.println (s);
  }
}

The missing element (denoted by xxx) is the:

26-10.

Consider the following Java program:

public class simpleMath {

   public static xxx fact ( int N ) {
      int retVal = N;
      for (int i=(N-1); i > 0; i--) {
         retVal = retVal * i;
      }
      return retVal;
   }
}

The missing element (denoted by xxx) is the:

26-11.

Suppose that you have compiled the following Java program and loaded it into the database:

public class simpleMath {

   public static xxx fact ( int N ) {
      int retVal = N;
      for (int i=(N-1); i > 0; i--) {
         retVal = retVal * i;
      }
      return retVal;
   }
}

Which of the following commands allows you to call the Java program from within PL/SQL to calculate a factorial?

26-12.

Put the following steps for accessing a Java class from PL/SQL in order:

26-13.

Show the operating system commands that load the following class into the SCOTT (password TIGER) schema:

public class helloWorld {
   public static void doit () {
       System.out.println("Hello World!!!");
   }
}

26-14.

Show the Oracle8i DDL command that loads the following class into the database:

public class helloWorld {
   public static void doit () {
       System.out.println("Hello World!!!");
   }
}

26-15.

What clause must you include in a function or procedure header to create a call spec for a Java method?

26-16.

What is the Java equivalent of the command SET SERVEROUTPUT ON?

26-17.

To publish a void Java method, you should use a PL/SQL:

26-18.

For each PL/SQL datatype in the left column, provide a corresponding Java datatype (there are many possible answers):

26-19.

Write a call spec for the following Java class:

public class OutputTest {
  public static void printIt (String s) {
     System.out.println (s);
  }
}

26-20.

Write a call spec for the following Java method:

public class Fibonacci {
  public static int fib (int n) {
    if (n == 1 || n == 2)
      return 1;
    else
      return fib(n - 1) + fib(n - 2);
  }
}

26-21.

The following Java program is saved in a file called test.java. What happens when you try to use javac to compile it?

public class helloWorld {
   public static void doit () {
       System.out.println("Hello World!!!");
   }
}

26-22.

Describe what happens when the call spec specified for the following class is created and executed:

public class helloWorld {
   public static void doit () {
       System.out.println("Hello World!!!");
   }
}

-- Call spec used for the class
CREATE OR REPLACE PROCEDURE my_hello
AS LANGUAGE JAVA
NAME 'helloWorld.doIt()';

26-23.

Describe what happens when the call spec specified for the following class is created and executed:

public class helloWorld {
   public void doit () {
       System.out.println("Hello World!!!");
   }
}

-- Call spec used for the class
CREATE OR REPLACE PROCEDURE my_hello
AS LANGUAGE JAVA
NAME 'helloWorld.doit()';

26-24.

Write a query to display information about the Java objects in a user schema.

26-25.

Write a procedure to print the source code for a Java-stored procedure (assuming, of course, that the source has been loaded).

26-26.

Write a call spec for the following Java class:

public class NumberTest{
  public static void smallestFirst (int[] a, int[] b) {
    int tmp = a[0];
    if (a[0] > b[0]) {
       a[0] = b[0];
       b[0] = tmp;
    }
  }
}

26-27.

Complete the following call spec:

CREATE OR REPLACE FUNCTION wages (e Employee) RETURN NUMBER
AS LANGUAGE JAVA
NAME 'Paymaster.wages( xxx ) return BigDecimal';

26-28.

You have been asked to design a PL/SQL interface for a subset of the methods in a Java file-manipulation class. Specifically, you are to write two functions and one procedure: a function that deletes a given file and returns a Boolean flag indicating whether the delete succeeded; a function that returns a file’s size; and a procedure that uses an OUT parameter, based on a index-by table type, to return the names of all the files in a given directory. Base your procedure on the following Java class:

import java.io.File;

public class JFile {

   public static int tVal () { return 1; };  // True Value
   public static int fVal () { return 0; };  // False Value
   public static String listDelimiter () { return "|"; };  // File Delimiter

   // Return the length of the file
   public static long length (String fileName) {
      File myFile = new File (fileName);
      return myFile.length();
      }

   // Delete a file
   public static int delete (String fileName) {
      File myFile = new File (fileName);
      boolean retval = myFile.delete();
      if (retval) return tVal(); else return fVal();
      }

   // Return a list of file names delimited by "|"
   public static String dirContents (String dir) {
      File myDir = new File (dir);
      String[] filesList = myDir.list();
      String contents = new String();
      for (int i = 0; i < filesList.length; i++)
         contents = contents + listDelimiter() + filesList[i];
      return contents;
      }

   /*
   || Lots more classes...
   */
}

Write a specification for your package.

26-29.

The Jfile class defined in 26-28 uses three “get” methods—tval(), fval(), and listDelimiter( )—to represent (respectively) the Boolean TRUE value, the Boolean FALSE value, and the delimiter character used by the dirContents method. As a first step in implementing your file package, develop a method to retrieve and use these same values in your PL/SQL program.

26-30.

Implement the function to delete a file; remember that it must return a Boolean value.

26-31.

Implement the function to retrieve a file’s size.

26-32.

Implement the procedure to populate an index-by table with the contents of a directory.

26-33.

Before you start using the package, you have to set up the appropriate permissions. What new role do you need to grant to a schema to allow it to read or write a file? What new role do you need to create a file? What INIT.ORA parameter do you need to modify to control the directories in which you can perform file operations?