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.

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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.

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Table 3.16.1.

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	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.

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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);
    }
  }

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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.

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Table 3.16.2.

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	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.

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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);
    }
  }

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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.

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    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.

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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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