1.10. Unit 1 Coding Practice¶

Update the main method to calculate and print the perimeter of a rectangle having width 7 and height 9. Add another statement to calculate and print the area of the rectangle on a separate line.

Update the main method to calculate and print the area of a triangle with base 7 and height 9. Recall the formula is 1/2bh. Your solution must contain at least one multiplication and one division. Watch out for integer division! int/int results in an int, while int/double results in a double.

R0 (pronounced R-naught) is a measure for predicting and controlling the transmission of disease. If R0 is 3, then each person that has a disease will spread it on average to 3 other people. The program below shows 4 iterations in the spread of SmallPox, which has an R0 of 3. The first person spreads to 3 people, each of whom spread to 3 people, etc. Update the program with additional print statements to show the spread after 4 iterations of HIV (R0 of 4) and Measles (R0 of 16).

In Unit 4 you will learn a better way to solve this problem using loops.

The following code should print “Mary’s favorite color is blue”. However, the code has errors. Fix the code so that it compiles and runs correctly. It is not an error for System.out.println to perform string concatenation across several lines of code, but there is a problem with one of the variables in the print statement.

public class Test1
{
    public static void main(String[] args)
    {
        String name = Mary";
        String color = "blue"
        System.out.println(Name +
                           "'s favorite color is " + color);
    }
}
====
import static org.junit.Assert.*;
  import org.junit.*;;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
      @Test
      public void testMain() throws IOException
      {
          String output = getMethodOutput("main");
          String expect = "Mary's favorite color is blue";
          boolean passed = getResults(expect, output, "Expected output from main");
          assertTrue(passed);
      }
      @Test
      public void testPrintStringsA() throws IOException
      {
        String target1 = "println(name +";
        boolean passed1 = checkCodeContains("System.out.println with name variable", target1);

assertTrue(passed1);
      }
      @Test
      public void testPrintStringsB() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ color") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with color variable", passed);
       assertTrue(passed);
      }
  }

Line 5 is missing a starting ". Line 6 is missing a ending ;. Line 7 has Name when it should be name. Remember that variable names start with a lowercase letter.

This is the answer to the previous question.

The following code should print “Gabby’s favorite sport is soccer”. However, the code has errors. Fix the code so that it compiles and runs correctly.

public class Test1
{
    public static void main(String[] args)
    {
        String name "Gabby";
        String sport = "soccer;
        System.out.println(Name +
                           "'s favorite sport is "
                           sport);
    }
}
====
import static org.junit.Assert.*;
  import org.junit.*;;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
      @Test
      public void testMain() throws IOException
      {
          String output = getMethodOutput("main");
          String expect = "Gabby's favorite sport is soccer";
          boolean passed = getResults(expect, output, "Expected output from main");
          assertTrue(passed);
      }
      @Test
      public void testPrintStringsA() throws IOException
      {
        String target1 = "println(name +";
        boolean passed1 = checkCodeContains("System.out.println with name variable", target1);

assertTrue(passed1);
      }
      @Test
      public void testPrintStringsB() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ sport") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with sport variable", passed);
       assertTrue(passed);
      }
  }

The following code should print “Your name is Carly and your favorite color is red”. Finish the code so that it prints the output correctly using the variables provided.

public class Test1
{
    public static void main(String[] args)
    {
        String name = "Carly";
        String color = "red";
        System.out.println();
    }

}
====
import static org.junit.Assert.*;
  import org.junit.*;;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
      @Test
      public void testMain() throws IOException
      {
          String output = getMethodOutput("main");
          String expect = "Your name is Carly and your favorite color is red";
          boolean passed = getResults(expect, output, "Expected output from main");
          assertTrue(passed);
      }
      @Test
      public void testPrintStringsA() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ name") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with name variable", passed);
       assertTrue(passed);
      }
      @Test
      public void testPrintStringsB() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ color") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with color variable", passed);
       assertTrue(passed);
      }
  }

Finish the code below so that it prints “Your name is Justin and your age is 16” using the variables provided.

public class Test1
{
    public static void main(String[] args)
    {
        String name = "Justin";
        int age = 16;
        System.out.println();

}
}
====
import static org.junit.Assert.*;
  import org.junit.*;;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
      @Test
      public void testMain() throws IOException
      {
          String output = getMethodOutput("main");
          String expect = "Your name is Justin and your age is 16";
          boolean passed = getResults(expect, output, "Expected output from main");
          assertTrue(passed);
      }
      @Test
      public void testPrintStringsA() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ name") ;
       boolean passed = count >= 1;

String code = getCode();
       int count = countOccurences(code, "+ age") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with age variable", passed);
       assertTrue(passed);
      }
  }

Write the code to print “Julian’s favorite color is green. His favorite food is pizza.” using the variables provided. Watch out for spaces and the period at the end of each sentence.

public class Test1
{
    public static void main(String[] args)
    {
        String name = "Julian";
        String color = "green";
        String food = "pizza";
        System.out.println();
    }
}
====
import static org.junit.Assert.*;
  import org.junit.*;;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
      @Test
      public void testMain() throws IOException
      {
          String output = getMethodOutput("main");
          String expect = "Julian's favorite color is green. His favorite food is pizza.";
          boolean passed = getResults(expect, output, "Expected output from main");
          assertTrue(passed);
      }
      @Test
      public void testPrintStringsA() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ color") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with color variable", passed);
       assertTrue(passed);
      }
      @Test
      public void testPrintStringsB() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ food") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with food variable", passed);
       assertTrue(passed);
      }
  }

Finish the code below to print your favorite movie and book.

public class Test1
{
    public static void main(String[] args)
    {
        String movie = "";
        String book = "";
        System.out.println();

}
}
====
import static org.junit.Assert.*;
  import org.junit.*;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
     @Test
      public void testPrintStringsA() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ movie") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with movie variable", passed);
       assertTrue(passed);
      }

@Test
      public void testPrintStringsB() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "+ book") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "System.out.println uses string concatenation with book variable", passed);
       assertTrue(passed);
      }

}

The following code should calculate the cost of a trip that is 300 miles if gas is $2.50 a gallon and your car gets 36 miles per gallon. However, the code has syntax errors, like missing semicolons, wrong case on names, or unmatched " or (. Fix the code so that it compiles and runs correctly.

public class Test1
{
    public static void main(String[] args)
    {
        int tripMiles = 300
        Double price = 2.50;
        int milesPerGallon = 30;
        double numberOfGallons = tripmiles / milesPerGallon;
        double totalCost = numberOfGallons * price;
        System.out.println(totalCost);
    }
}
====
import static org.junit.Assert.*;
  import org.junit.*;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
      @Test
      public void testMain() throws IOException
      {
          String output = getMethodOutput("main");
          String expect = "25.0";
          boolean passed = getResults(expect, output, "Expected output from main");
          assertTrue(passed);
      }
      @Test
      public void testPrintStringsB() throws IOException
      {

String code = getCode();
       int count = countOccurences(code, "double price") ;
       boolean passed = count >= 1;

passed = getResults("1 count", "" + count  + " count", "Declare the variable using type double, not Double", passed);
       assertTrue(passed);
      }
  }

The following code should calculate the number of miles that you can drive when you have $8.00 and the price of gas is 2.35 and the car gets 40 miles per gallon. However, the code has errors. Fix the code so that it compiles and runs correctly.

public class Test1
{
    public static void main(String[] args)
    {
        gallonPrice = 2.35;
        40 = double milesPerGallon;
        double totalFunds = 8.0;
        double numGallons = totalFunds gallonPrice;
        double numMiles = numGallons * milesPerGallon;
        System.out.println(numMiles;
    }
}
====
import static org.junit.Assert.*;
  import org.junit.*;
  import java.io.*;
   public class RunestoneTests extends CodeTestHelper
  {
      @Test
      public void testMain() throws IOException
      {
          String output = getMethodOutput("main");
          String expect = "136.17021276595744\n";
          boolean passed = getResults(expect, output, "Expected output from main");
          assertTrue(passed);
      }
      @Test
      public void testPrintStringsB() throws IOException
      {
       String target = "numGallons = totalFunds / gallonPrice";
       boolean passed = checkCodeContains("formula for numGallons", target);
       assertTrue(passed);
      }

}

The following code should calculate the cost of an item that is on clearance (70% off) when you also have a coupon for an additional 20% off the clearance price. However, the code has errors. Fix the code so that it compiles and runs correctly.

The following code should calculate the number of whole days in 320893 seconds. However, the code has errors. Fix the code so that it compiles and runs correctly.

Complete the code below to calculate and print how many months it will take to save $200 if you earn $20 a week. First calculate how many weeks it would take to make $200, then calculate how many months it will take assuming there are 4 weeks per month.

Write the code to calculate the number of miles you can drive if you have a 10 gallon gas tank and are down to a quarter of a tank of gas and your car gets 32 miles per gallon.

public class Test1
{
    public static void main(String[] args)
    {
       // Your code should use the variables
       // numGallons, milesPerGallon, and miles
       // and print out miles
    }
}
====
import static org.junit.Assert.*;
  import org.junit.*;
  import java.io.*;

public class RunestoneTests extends CodeTestHelper
  {
    @Test
    public void testMain() throws IOException
    {
      String output = getMethodOutput("main");
      String expect = "80.0\n";
      boolean passed = getResults(expect, output, "Expected output from main");
      assertTrue(passed);
    }

@Test
    public void testFormulaMiles() throws IOException
    {

String code = getCode();
       int count1 = countOccurences(code, "double miles = numGallons * milesPerGallon") ;
       int count2 = countOccurences(code, "double miles = milesPerGallon * numGallons") ;

boolean passed = count1+count2 >= 1;

passed = getResults("1 count", "" + (count1 +count2)  + " count", "calculation for miles using numGallons and milesPerGallon", passed);
      assertTrue(passed);
    }
  }

Write the code to calculate the number of seconds in 3 days. Remember that there are 60 seconds in a minute and 60 minutes in an hour and 24 hours in a day.

public class Test1
{
    public static void main(String[] args)
    {
       // Your code should use the variables
       // secondsInDay and secondsInThreeDays
       // and print out secondsInThreeDays

}
}
====
import static org.junit.Assert.*;
  import org.junit.*;
  import java.io.*;
  public class RunestoneTests extends CodeTestHelper
  {
    @Test
    public void testMain() throws IOException
    {
      String output = getMethodOutput("main");
      String expect = "259200\n";
      boolean passed = getResults(expect, output, "Expected output from main");
      assertTrue(passed);
    }

@Test
    public void testFormulaMiles() throws IOException
    {

String code = getCode();
       int count1 = countOccurences(code, "int secondsInThreeDays = secondsInDay * 3") ;
       int count2 = countOccurences(code, "int secondsInThreeDays = 3 * secondsInDay") ;

boolean passed = count1+count2 >= 1;

passed = getResults("1 count", "" + (count1 +count2)  + " count", "formula for secondsInThreeDays using secondsInDay", passed);
      assertTrue(passed);

}
  }

Write the code to print the number of chicken wings you can buy if you have $4.50 and they cost $0.75 each. Remember that you can’t buy part of a wing. Divide the amount of money you have by the cost of each wing and then use casting to set the result to an int since you can’t buy a part of a wing.

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