CSE 17  Test 2   Tuesday  15 November 2005
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1. Design  a class called Dictionary that is a subclass of the Book class.
Create the methods in Dictionary so that word.main() produces the following
output.
Number of pages: 1500
Number of definitions: 52500
Defintions per page: 35.0
Note: 52500/1500  =  35.0

public class Words {
  public static void main(String[] args) {
    Dictionary webster = new Dictionary(1500,52500);
    // 1500 is number of pages & 52500 is number of definitions
    System.out.println(webster);
    System.out.println("Note: " + webster.getDefinitions() + "/"
       + webster.getPages() + "  =  " + webster.computeRatio());
   }
}
   class Book
   {protected int pages = 1500;
    public Book(int p) {pages = p;}

    public int getPages(){return pages;}

    public String toString(){return "Number of pages: "+ pages;}
   }
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class Dictionary extends Book
   {private int definitions;
      public Dictionary (int p, int numDef){
                          super(p);
                   definitions = numDef;}

      public double computeRatio(){return definitions/pages;}
           
      public int getDefinitions(){return definitions;}
           
      public String toString()
        {return (super.toString() + "\nNumber of definitions: " + definitions
                 + "\nDefintions per page: " + computeRatio());}
   }

Name_______________________________________________________________
2. This question has two distinct parts. Answer each part
Part a) Given the following classes, state the output if in the interaction
        pane I typed the following:

>x = new C()
>x.e()

public class A{
        protected int j;
        public A(A b){j=b.j;}
        public A(){j=22;}
        public static void stat(){System.out.println("I am in A.stat"); }
        public  void a(){j = 40;        }
        protected void b(){j = j + 10;}
        void c(){j = 80;}
        private void d(){j = j*j;}
        public void e(){
          stat();
          System.out.println(j);
          a();
          System.out.println(j);
          b();
          System.out.println(j);
          c();
          System.out.println(j);
          d();
          System.out.println(j);}
}

class C extends A
{public static void stat(){System.out.println("I am in C.stat");}
 public void a(){j = 5;}
 protected void b(){j = 10;}
 void c(){j = 30;}
 private void d(){j = 50;}
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I am in A.stat
22
5
10
30
900
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Part b) Explain the behavior of class T2 when T2.main() executes.
import java.util.*;
import java.io.*;
public class T2 {

  public static void main(String[] args) {
    Scanner f;
    try
    {f=new Scanner(new FileInputStream("junk"));
     System.out.println(f.nextInt());
    }
    catch(FileNotFoundException e)
    {System.out.println("Jerko");
     System.exit(1);
    }
    catch(Exception e)
    {System.out.println("Dumbo");
     System.exit(2);
    }
   }
  }
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If the file 'junk' does not exist, the program displays "Jerko"
If the file 'junk' exists, but if there is something other than a leading
   digit, it displays "Dumbo"
If the file 'junk' exists, and there is a leading digit, it reads in an
   int and displays it
If any other kind of error ocurrs, the program displays "Dumbo"
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3.  Write a recursive method, called max, that finds the largest number
    in an array of ints, using the following recursive algorithm, WHICH
    YOU MUST NOT CHANGE: to find the maximum of the entries from location
    a to location b in the array, divide the array in half, find the
    largest number in each half, and return the larger of these two
    numbers.  If we have
      int [] x={0, 5, 6, 8, 2, 9, 20, 31, 12};
    the call to find the largest of the 9 entries in the array x would be
      max(x,0,8);
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public int max(int [] x,int bot, int top)
{if(bot>=top)
   return x[bot];
 return max( max(x,bot,(bot+top)/2),
             max(x,(bot+top)/2+1,top));
}
public int max(int a,int b)
{if(a<b)
    return b;
 return a;
}
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4. Write a method, positive, that reads a file consisting solely of ints and
   returns true if every number in the file is greater than 0 and returns
   false otherwise.  If we have the declaration
      FileInputStream f;
   and f is opened on some input file then the call to positive would be
      positive(f)
   where positive can assume that the file f is open for reading.
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public boolean positive(FileInputStream f)
{Scanner scan=new Scanner(f);
 while(scan.hasNextInt())
 if(scan.nextInt()<=0)
    return false;
 return true;
}
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