FRQ 2 Practice with Classes

Section 3.16 FRQ 2 Practice with Classes

Many of the FRQs on the AP exam contain a table which shows output or return values from methods in a class. In these practice exercises, you will be given a table that shows method calls and their output. You will need to write a class with the described methods that will produce the output shown in the table. Thank you to Sam Procopio from Bishop Blanchet High School in Seattle, WA, for these exercises.

Subsection 3.16.1 Tree Class

Write a class called Tree that has the appropriate instance variables and methods to produce the output described in the table below.

Table 3.16.1.

	Method Calls	Output
	Tree birch = new Tree(10, “soft”);
	System.out.println(birch.getHeight());	10
	birch.water(5);
	System.out.println(birch.getHeight());	15
	birch.cut();
	System.out.println(birch.getHeight());	7
	System.out.println(birch.woodType());	soft wood
	Tree oak = new Tree(20, “hard”);
	System.out.println(oak.getHeight());	20
	System.out.println(oak.woodType());	hard wood
	oak.water(2);
	System.out.println(oak.getHeight());	22
	oak.cut();
	System.out.println(oak.getHeight());	14

Activity 3.16.1.

Write the class Tree below with the appropriate instance variables, constructor, and methods described in main method and in the table above.

public class Tree
{
    // write instance variable declarations here
  
  
    // write the constructor and other methods here
  
  
    public static void main(String[] args)
    {
        Tree birch = new Tree(10, "soft");
        System.out.println(birch.getHeight());
        birch.water(5); // grows tree height by 5
        System.out.println(birch.getHeight());
        birch.cut(); // cuts off 8 from height
        System.out.println(birch.getHeight());
        System.out.println(birch.woodType());
  
        Tree oak = new Tree(20, "hard");
        System.out.println(oak.getHeight());
        System.out.println(oak.woodType());
        oak.water(2); // grows tree height by 2
        System.out.println(oak.getHeight());
        oak.cut(); // cuts off 8 from height
        System.out.println(oak.getHeight());
    }
  }
====
import static org.junit.Assert.*;
import org.junit.*;
import java.io.*;    
public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("Tree");
    }

@Test
    public void testMain()
    {
        String expected = "10\n15\n7\nsoft wood\n20\nhard wood\n22\n14\n";
        String output = getMethodOutput("main");

boolean passed = getResults(expected, output, "Checking main method output");
        assertTrue(passed);
    }
    @Test
    public void test2()
    {          
        String results = checkConstructor(2);

boolean passed = getResults("pass", results, "Checking constructor with 2 parameters");
        assertTrue(passed);
    }

@Test
    public void test3()
    {
        String actual = testPrivateInstanceVariables();
        String expected = "2 Private";

boolean passed = getResults(expected, actual, "Checking declaration of instance variables");
        assertTrue(passed);
    }
    @Test
    public void test4() {
      boolean passed = checkCodeContains("public water method with an int parameter", "public void water(int");
     assertTrue(passed);
    }
    @Test
    public void test5() {
      boolean passed = checkCodeContains("public cut method", "public void cut()");
     assertTrue(passed);
    }
    @Test 
    public void test6() {
      boolean passed = checkCodeContains("public woodType method that returns a String", "public String woodType()");
     assertTrue(passed);
    }
    @Test
    public void test7() {
      boolean passed = checkCodeContains("public getHeight method that returns an int", "public int getHeight()");
     assertTrue(passed);
    }
  }

Subsection 3.16.2 Book Class

Based on the table below, write a complete class called Book that has the appropriate instance variables and methods to produce the output described in the table.

Table 3.16.2.

	Method Calls	Output
	Book hp = new Book(“Harry Potter”, 150, true);
	System.out.println(hp.getNumPages());	150
	System.out.println(hp.getName());	Harry Potter
	System.out.println(hp.isHardCover());	true
	System.out.println(hp.getDamages());	0
	System.out.println(hp.repairBook());	false
	hp.addDamages(49);
	System.out.println(hp.getDamages());	49
	System.out.println(hp.repairBook());	false
	hp.addDamages(1);
	System.out.println(hp.getDamages());	50
	System.out.println(hp.repairBook());	true

Activity 3.16.2.

Write the class Book below with the appropriate instance variables, constructor, and methods described in main method and in the table above.

public class Book
{
    // write instance variable declarations here
   
    // write the constructor and other methods here
   
    public static void main(String[] args)
    {
        Book hp = new Book("Harry Potter", 150, true);
        System.out.println(hp.getNumPages());
        System.out.println(hp.getName());
        System.out.println(hp.isHardCover());
        System.out.println(hp.getDamages());
        System.out.println(hp.repairBook()); // should be false
  
        hp.addDamages(49);
        System.out.println(hp.getDamages());
        System.out.println(hp.repairBook()); // should be false
  
        hp.addDamages(1);
        System.out.println(hp.getDamages());
        System.out.println(hp.repairBook()); // should be true
    }
  }
====
import static org.junit.Assert.*;
import org.junit.*;
import java.io.*;
public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("Book");
    }

@Test
    public void testMain()
    {
        String expected = "150\nHarry Potter\ntrue\n0\nfalse\n49\nfalse\n50\ntrue\n";
        String output = getMethodOutput("main");

boolean passed = getResults(expected, output, "Checking main method output");
        assertTrue(passed);
    }
    @Test
    public void test2()
    {          
        String results = checkConstructor(3);

boolean passed = getResults("pass", results, "Checking constructor with 3 parameters");
        assertTrue(passed);
    }

@Test
    public void test3()
    {  
        String expect = "3 Private";
        String output = testPrivateInstanceVariables();
        boolean passed = false;
        if (Integer.parseInt(expect.substring(0, 1)) <= Integer.parseInt(output.substring(0, 1)))
            passed = true;
        passed = getResults(expect, output, "Checking private instance variables", passed);
        assertTrue(passed);
    }
    @Test
    public void test4() {
      boolean passed = checkCodeContains("public addDamages method with an int parameter", "public void addDamages(int");
     assertTrue(passed);
    }
    @Test
    public void test5() {
      boolean passed = checkCodeContains("public repairBook method that returns a boolean", "public boolean repairBook()");
     assertTrue(passed);
    }
    @Test
    public void test6() {
      boolean passed = checkCodeContains("public getNumPages method that returns an int", "public int getNumPages()");
     assertTrue(passed);
    }
  }

Subsection 3.16.3 Present Class

Write a class called Present that describes a gift for an occasion. Use the method calls in the main method below to create the appropriate instance variables and methods for the Present class.

    public static void main(String[] args)
    {
        //creates a Present object
        Present gift = new Present("Birthday", 29.99, "Legos");

        //prints out the gift name and cost 
        System.out.println("The gift is " + gift.getName() 
                  + ", and it costs $" + gift.getPrice() );
        
        // prints out the reaction "Wow!"
        System.out.println("The reaction when opening the gift was " 
                + gift.reaction() ); 
        // Prints out "Purchased at local store"
        gift.purchasedAt("local store");
    } 
}

Activity 3.16.3.

Write the class Present below with the appropriate instance variables, constructor, and methods described in main method.

public class Present
{
    // Write the instance variables here

// Write the constructor here

// Write the methods here
  
  
    public static void main(String[] args)
    {
        //creates a Present object
        Present gift = new Present("Birthday", 29.99, "Legos");

//prints out the gift name and cost
        System.out.println("The gift is " + gift.getName() 
                  + ", and it costs $" + gift.getPrice() );
        
        // prints out the reaction "Wow!"
        System.out.println("The reaction when opening the gift was " 
                + gift.reaction() ); 
        // Prints out "Purchased at local store"
        gift.purchasedAt("local store");
    } 
}
====
import static org.junit.Assert.*; 
import org.junit.*;
import java.io.*;
public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("Present");
    }

@Test
    public void testMain()
    {
        String expected = "The gift is Legos, and it costs $29.99\nThe reaction when opening the gift was Wow!\nPurchased at local store\n";
        String output = getMethodOutput("main");

boolean passed = getResults(expected, output, "Checking main method output", true);
        assertTrue(passed);
    }
    @Test
    public void test2()
    {          
        String results = checkConstructor(3);

boolean passed = getResults("pass", results, "Checking constructor with 3 parameters");
        assertTrue(passed);
    }

@Test
    public void test3()
    {
        String expect = "2 Private";
        String output = testPrivateInstanceVariables();
        boolean passed = false;
        if (Integer.parseInt(expect.substring(0, 1)) <= Integer.parseInt(output.substring(0, 1)))
            passed = true;
        passed = getResults(expect, output, "Checking private instance variable(s)", passed);
        assertTrue(passed);
    }
    @Test
    public void test4() {
      boolean passed = checkCodeContains("public getName method that returns a String", "public String getName()");
     assertTrue(passed);
    }
    @Test
    public void test5() {
      boolean passed = checkCodeContains("public getPrice method that returns a double", "public double getPrice()");
     assertTrue(passed);
    }
    @Test
    public void test6() {
      boolean passed = checkCodeContains("public reaction method that returns a String", "public String reaction()");
     assertTrue(passed);
    }
    @Test
    public void test7() {
      boolean passed = checkCodeContains("public purchasedAt method with a String parameter", "public void purchasedAt(String");
     assertTrue(passed);
    }
  }

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