Midterm Exam Answers -- Winter 14

Part A.

1. False. You specify the command line arguments in Eclipse with
   Run >> Run configurations... >> Arguments Tab. Type them into Program arguments.
   
2. True.  char c = 'B';
          int n = (int) c;
          The ASCII code of c is assigned to n, which is 66.
          
3. False. The possible return values are 3 and 4.  Math.random cannot actually return 1.
          Note: rather than using Math.random, it is usually more convenient to create
          a Random object and call its nextInt(n) method to get a random int in the range
          0 to n-1.
          
4. True   Pass the Scanner object a URL object to read from the web.

5. True   Use StringBuilder objects if you want mutable (changeable objects).

6. False  A constructor does not have a return type.

7. False  The Windows end of line terminator is \r\n, which in hex is 0d0a.

8. False  Use a PrintWriter object.

9. True

10. True  This is the definition of an instance method.

Part B.

Not discussed this quarter.

Part C.

1.  public static boolean isSorted(double[ ] arr) {
        return arr[0] <= arr[1] && arr[1] <= arr[2];
    }
    public static void main(String[ ] args) {
        double[ ] a1 = {3.4565, 7.5454, 9.3291};
        double[ ] a2 = {7.5454, 3.4565, 9.3291};
        System.out.println(isSorted(a1) + " " +isSorted(a2));
    }
    // Output: true false
    
2.  public static int countWords(String input) {
        return input.split(" ").length;
    }
    public static void main(String[ ] args) {
        String s = "This is a test.";
        System.out.println(countWords(s));
    }
    
Part  C:   

1.
public class CashRegister {
	public double _totalAmountOfSale;  <-- Should be private
	public int _totalItems;            <-- Should be private
	
	public void CashRegister( ) {      <-- void not allowed for constructor
		this.clear( );
	}
	public double getTotalAmountOfSale( )  <-- Add { at end of line.
		return _totalAmountOfSale;
	}
	public int getTotalItems( ) {
		return totalItems;             <-- Add _ at beginning of totalItems.
	}
	public void enterItem(double amount) {
         _totalAmountOfSale += amount;
         _totalItems += 1;
         System.out.print('Price of item: %$6.2f/n' <-- Need double quotes (2 errors).
                                                    <-- Change /n to \n.
                                                    <-- Swap % and $.
             amount);           
     }
     public clear( ) {                 <-- Need public void clear.
         _totalAmountOfSale = 0.0;
         _totalItems = 0		
     }
                                        <-- Missing }
                                        
2.
public static void main(String[ ] args) {
    CashRegister cr = new CashRegister( );
    cr.enterItem(34.54);
    System.out.println(cr.getTotalItems( ));
    System.out.println(cr.getTotalAmountOfSale( ));
    cr.clear( );
    System.out.println(cr.getTotalItems( ));
    System.out.println(cr.getTotalAmountOfSale( ));    
}                              

Part D:

1. 
import java.awt.print.Paper;
public class Main {

    public static void main(String[] args) {
		
        Paper p = new Paper( );
        System.out.println(p.getHeight()/72.0 + " " 
            + p.getWidth()/72.0);
        System.out.println(p.getImageableHeight()/72.0 + " " 
		    + p.getImageableWidth()/72.0);
	}
}
// Output: 8.5 11
           6.5 9