Practice Exam Answers -- March 13, 2016

Part A. Multiple Choice Questions

 1. a   2. b   3. b   4. d   5. b
 6. c   7. a   8. c   9. a  10. d
11. a  12. c

Part B: Predict the Fill Order

    +---+
    | 4 |
+---+---+---+
| 1 | + | 2 |
+---+---+---+
    | 3 |
    +---+

    0   1   2   3   4   5   6    
  +---+---+---+---+---+---+---+
0 | * | * | * | * | * | * | * |
  +---+---+---+---+---+---+---+
1 |   |   | * |11 | * |10 | * |
  +---+---+---+---+---+---+---+
2 | * | * | 6 | 7 | 8 | 9 | * |
  +---+---+---+---+---+---+---+
3 | * | 3 | 2 | 1 |12 | * | * |
  +---+---+---+---+---+---+---+
4 | * | * | 4 | 5 | * |   | * |
  +---+---+---+---+---+---+---+
5 | * |   | * | * |   |   | * |
  +---+---+---+---+---+---+---+
6 | * | * | * | * | * | * | * |
  +---+---+---+---+---+---+---+

Part C: Write Unit Tests

//------- Source code file: DogTest.java 
public class DogTest { 
    Dog _d; 
    @Before 
    public void setUp( ) { 
        _d = new Dog("Duke", "Maxwell", 3, "German Shephard"); 
    } 
    @Test 
    public void testGetBreed( ) { 
        assertEquals(_d.getBreed( ), "German Shephard");
    } 
    
    @Test 
    public void testSetAge( ) { 
        _d.setAge(5);
        assertEquals(_d.getAge( ), 5);
    
    } 
    
    @Test 
    public void testToString( ) { 
        assertEquals(_d.toString( ), "Duke Maxwell 3 German Shephard");
    } 
} 

Part D: Find Errors

//------- Source code file Main1.java. 
package it313.finalexam.petsalon; 
import java.sql.*; 
import java.util.HashMap; 
require java.util.Map.Entry; 
public class Main1 { 
    public static void main(String[] args)  
        throws ClassNotFoundException, SQLException  { 
        
        // Create HashSet that contains 4 Dog objects. 
        HashMap<String, Dog> col = new HashMap<String, Dog>( ); 
        col.put("D1", new Dog("Duke", "Maxwell", 3, "German Shephard")); 
        col.put("D2", new Dog("Sparky", "Rogers", 1, "Dachshund"); 
        col.put("D3", new Dog("Mimi", "Sanchez", 1, "Pomeranian")); 
        col.put("D4", new Dog("Ginger", "Saari", 4, "Collie")); 
        System.out.println(col); 
        
        // Create Connection and Statement objects. 
        Class.forName("org.sqlite.JDBC"); 
        Connection c = DriverManager.getConnection("jdbc:sqlite:dogs.db"); 
        Statement s = c.createStatement( ); 
        
        // Create new dogs table, if it doesn't already exist. 
        String sql1 = "create table if not exists dogs(" + 
                          "name varchar(10), " + 
                          "owner varchar(10), " + 
                          "age integer, " + 
                          "breed varchar(10));";  
        s.executeUpdate(sql1); 

//------- Source code file Main1.java (continued) 

        // Populate table with dogs from collection. 
        for(Entry<String, Dog> e : col.entrySet( )) { 
            Dog d = e.getKey( ); 
            String sql2 = String.format( 
               "insert into dogs values('%s', '%s', %d, '%s');", 
               d.getName( ), d.getOwner( ), d.getAge( ), d.getBreed( )); 
         }
         s.executeUpdate(sql2);
    } 
}

Part D: Correct the errors

// ------------ Source code file Main2.java 

import java.io.FileNotFoundException; 
public class Main2 { 
    public static void main(String[ ] args) throws FileNotFoundException { 
        TornadoSimulator[ ] simulators =  
                 { new TornadoSimulator("Cook"), 
                   new TornadoSimulator("DuPage"),  
                   new TornadoSimulator("Kane"), 
                   new TornadoSimulator("Lake"),  
                   new TornadoSimulator("McHenry"), 
                   new TornadoSimulator("Will") }; 
        TornadoObserver observer = new TornadoObserver("logfile.txt"); 
        
        for(TornadoSimulator sim : simulators) { 
            sim.addObserver(observer); 
        } 
             
        for(int day = 1; day <= 1000; day++) { 
            for(TornadoSimulator sim : simulators) { 
                sim.checkForTornado( ); 
            } 
         } 
     } 
 } 
 
// ----- Source code file TornadoSimulator.java 

import java.util.Observable; 
import java.util.Random; 
public Class TornadoSimulator super Observable { 
    private String _county; 
    private Random _r; 
    public TornadoSimulator(String theCounty) { 
        _county = theCounty; 
        _r = new Random( ); 
    } 

    public void checkForTornado( ) { 
        if( _r.nextInt(1000) = 999) { 
            notifyObservers(this, "County: " + _county); 
            setChanged( ); 
       
        }
    }
}

// ----- Source code file TornadoObserver.java 
import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.PrintWriter; 
import java.util.Observable; 
import java.util.Observer; 
public class TornadoObserver implements Observer { 
    PrintWriter _pw; 
    
    public TornadoObserver(String the_file_name) throws FileNotFoundException { 
        File f = new File(theFileName); 
        PrintWriter _pw = new PrintWriter(f); 
    } 

    @Override 
    public void update(Observable theSimulator, Object theMessage) { 
        _pw.println(theMessage); 
        pw.flush( )
    }
}