Unit 7 Write Code for Toggle Code

The following program should create a List called conversation, add in some elements("hello", "goodbye", "how are you", and "see you later"), and print out the elements with ", " after each. Fill in the code so that it adds the elements to conversation. The rest of the program is finished for you.

import java.util.ArrayList;
import java.util.List;

public class ListTest
{

public static void main(String[] args)
    {

List<String> conversation;
        conversation = new ArrayList<String>();

// YOUR CODE HERE //

for (String element : conversation)
        {

System.out.print(element + ", ");
        }
    }
}

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect = "hello, goodbye, how are you, see you later,";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }

// @Test
    public void test2()
    {
        String code = getCodeWithoutComments();
        System.out.println("Stuck here");

int count = countOccurences(code, "new ArrayList");
        boolean passed = getResults("1", "" + count, "Counting number of new ArrayList");
        assertTrue(passed);
    }

// @Test
    public void test3()
    {
        String code = getCodeWithoutComments();
        // System.out.println("Stuck here");
        int count = countOccurences(code, ".add(");
        boolean passed = getResults("4", "" + count, "Counting number of .add()");
        assertTrue(passed);
    }
}

Fix the two errors in the printBackwards method so that it will correctly iterate through the parameter myList backwards and print each element.

import java.util.ArrayList;

public class ListTest
{

public static void printBackwards(ArrayList<String> myList)
    {

for (int i = myList.size() - 1; i > 0; i--)
        {

System.out.print(myList[i] + ", ");
        }
    }

public static void main(String[] args)
    {

ArrayList<String> conversation;
        conversation = new ArrayList<String>();

conversation.add("hello");
        conversation.add("goodbye");
        conversation.add("how are you");
        conversation.add("see you later");

printBackwards(conversation);
    }
}

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

// import java.util.ArrayList;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect = "see you later, how are you, goodbye, hello,";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }
}

Write code to define the removeZeros method. This method should take in an ArrayList of integers listOfNums and delete all of the zeros. For example, {3, 0, 5, 0} would change into {3, 5}.

import java.util.ArrayList;

public class ListTest
{

public static void removeZeros(ArrayList<Integer> listOfNums)
    {
        // YOUR CODE HERE

// HINT: When you delete an element, the indexes of the following elements
        // shift!
        // That means you CANNOT use an enhanced for loop
        // And it also means you need to carefully handle when you increment your
        // index variable

}

public static void main(String[] args)
    {

ArrayList<Integer> list;
        list = new ArrayList<Integer>();

list.add(1);
        list.add(0);
        list.add(0);
        list.add(3);
        list.add(2);
        list.add(0);
        list.add(9);

System.out.println("Before: " + list);
        removeZeros(list);
        System.out.println("After: " + list);
    }
}

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

// import java.util.ArrayList;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect = "Before: [1, 0, 0, 3, 2, 0, 9]\nAfter: [1, 3, 2, 9]";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }
}

Write code for the findSmallest method. This code segment should take in an ArrayList nums and return the smallest element present. For example, findSmallest called on {5, 3, 1, 6} should return 1.

Write code to flesh out the removeOdd method. This method should take in a parameter nums and delete every odd number from it. For example, {5, 3, 2, 1, 4} should become {2, 4}.

import java.util.ArrayList;

public class ListTest
{

public static void removeOdd(ArrayList<Integer> nums)
    {

// YOUR CODE HERE //
        // Just like in problem three, be wary about the changing indexes

}

public static void main(String[] args)
    {

ArrayList<Integer> list;
        list = new ArrayList<Integer>();

list.add(12);
        list.add(7);
        list.add(16);
        list.add(39);
        list.add(28);
        list.add(40);
        list.add(9);

System.out.println("Before: " + list);
        removeOdd(list);
        System.out.println("After: " + list);
    }
}

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect = "[12, 16, 28, 40]";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }
}

Fill out the average method. It should take in an ArrayList nums and calculate the arithmetic mean (the sum divided by the length). For example, average called on {5, 9, 6} should return 6.66666666667 as that is (5 + 9 + 6) / 3.

Create the moveLargest method. This should find the largest value in an ArrayList of Integers (the parameter) and move it to the back of the list.

import java.util.ArrayList;

public class ListTest
{

public static void moveLargest(ArrayList<Integer> nums)
    {

// YOUR CODE HERE //

} // end moveLargest method

public static void main(String[] args)
    {

ArrayList<Integer> list;
        list = new ArrayList<Integer>();

list.add(1);
        list.add(3);
        list.add(12);
        list.add(0);
        list.add(9);

System.out.println("Before: " + list);
        moveLargest(list);
        System.out.println("After: " + list);
    } // end main method
} // end class

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

// import java.util.ArrayList;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect = "Before: [1, 3, 12, 0, 9]\nAfter: [1, 3, 0, 9, 12]";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }
}

Write code to finish the removeShort method. It should take an ArrayList words and remove all elements that are three characters long or shorter. For example, {"Dog", "Monkey", "Lion", "Cat"} would become {"Monkey", "Lion"}.

import java.util.ArrayList;

public class ListTest
{

public static void removeShort(ArrayList<String> words)
    {

// YOUR CODE HERE //
        // Just like in problem three, consider iterating backwards or using a
        // while loop

} // end removeShort method

public static void main(String[] args)
    {

ArrayList<String> list;
        list = new ArrayList<String>();

list.add("catch");
        list.add("dog");
        list.add("tree");
        list.add("me");

System.out.println("Before: " + list);
        removeShort(list);
        System.out.println("After: " + list);
    } // end main method
} // end class

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect = "Before: [catch, dog, tree, me]\nAfter: [catch, tree]";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }
}

Write the method doubleList. This should take in an ArrayList words and insert a copy of each element such that {"cat", "ribbon", "house"} would become {"cat", "cat", "ribbon", "ribbon", "house", "house"}.

import java.util.ArrayList;

public class ListTest
{

public static void doubleList(ArrayList<String> words)
    {

// YOUR CODE HERE
        // Remember - when you insert elements, you'll change the indexes!

} // end doubleList method

public static void main(String[] args)
    {

ArrayList<String> list;
        list = new ArrayList<String>();

list.add("catch");
        list.add("dog");
        list.add("tree");
        list.add("me");

System.out.println("Before: " + list);
        doubleList(list);
        System.out.println("After: " + list);
    } // end main method
} // end class

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect =
                "Before: [catch, dog, tree, me]\n"
                    + "After: [catch, catch, dog, dog, tree, tree, me, me]";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }
}

Write the method removeElement. This should take in an ArrayList nums and an integer toRemove and remove every instance of that integer from nums. E.g., if nums was {3, 6, 5, 3, 4}, it should become {6, 5, 4} after calling removeElement(nums, 3).

import java.util.ArrayList;

public class ListTest
{

public static void removeElement(ArrayList<Integer> nums, int toRemove)
    {

// YOUR CODE HERE

} // end average method

public static void main(String[] args)
    {

ArrayList<Integer> list;
        list = new ArrayList<Integer>();

list.add(1);
        list.add(3);
        list.add(2);
        list.add(9);

System.out.println("Before: " + list);
        removeElement(list, 3);
        System.out.println("After: " + list);
    } // end main method
} // end class

====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

public class RunestoneTests extends CodeTestHelper
{
    public RunestoneTests()
    {
        super("ListTest");
    }

@Test
    public void test1()
    {
        String output = getMethodOutput("main");
        String expect = "Before: [1, 3, 2, 9]\nAfter: [1, 2, 9]";

boolean passed = getResults(expect, output, "Running main");
        assertTrue(passed);
    }
}

Unit 7 Write Code for Toggle Code¶