Question

Hi,

I am having trouble solving the constructor, it requires to ArrayList marks to be a deep copy of the instance variable. I have also provided the J-Unit test I have been provided.

import java.util.*;

public class GradebookEntry {

private String name;

private int id;

private ArrayList<Double> marks;

/**

* DO NOT MODIFY

*/

public String toString() {

String result = name+" (ID "+id+")\t";

for(int i=0; i < marks.size(); i++) {

/**

* display every mark rounded off to two digits.

* adding the 0.00001 to compensate for any rounding-off errors.

*/

double displayMark = (int)((marks.get(i)+0.00001)*100)/100.0;

result+=displayMark+"\t";

}

double displayTotal = (int)(getTotal()*100)/100.0;

return result.substring(0, result.length()-1)+"\t(Total "+displayTotal+")\n";

}

/**

* DO NOT MODIFY

* @return name of the student

*/

public String getName() {

return name;

}

/**

* DO NOT MODIFY

* @return id

*/

public int getId() {

return id;

}

/**

* DO NOT MODIFY

* @return number of assessments

*/

public int numberOfAssessments() {

return marks.size();

}

/**

* set the instance variable id to the parameter provided.

* if i is less than 1, id should become 1.

* otherwise, id should become i.

* @param i

*/

private void setId(int i) {

if( i < 1){

id = 1;

} else {

id = i;

}

}

/**

* set instance variables name, id and marks to corresponding parameter provided.

* use the setter to set the id.

* you should make a deep copy for marks, NOT A SHALLOW COPY

* @param name

* @param id

* @param marks

*/

public GradebookEntry(String name, int id, ArrayList<Double> marks) {

this.name = name;

this.setId(id);

//Stuck on setting marks, there is no setMarks method either

}

}

This is the J-Unit Test they provided as well:

@Test

public void testGradebookEntry() {

GradebookEntry entry = new GradebookEntry("Joshua Lyman", 5, new ArrayList<Double>(Arrays.asList(1.5, 4.5, 2.5, 8.5)));

assertEquals("Joshua Lyman", entry.getName());

assertEquals(5, entry.getId());

assertEquals(4, entry.numberOfAssessments());

assertEquals(1.5, entry.getMark(0), 0.0001);

assertEquals(4.5, entry.getMark(1), 0.0001);

assertEquals(2.5, entry.getMark(2), 0.0001);

assertEquals(8.5, entry.getMark(3), 0.0001);

}

Answer 1

Answer:

GradebookEntry.java

import java.util.*;

public class GradebookEntry {

private String name;

private int id;

private ArrayList<Double> marks;

/** DO NOT MODIFY */

public String toString() {

String result = name + " (ID " + id + ")\t";

for (int i = 0; i < marks.size(); i++) {

/** display every mark rounded off to two digits. adding the 0.00001

* to compensate for any rounding-off errors. */

double displayMark = (int) ((marks.get(i) + 0.00001) * 100) / 100.0;

result += displayMark + "\t";

}

double displayTotal = (int) (getTotal() * 100) / 100.0;

return result.substring(0, result.length() - 1) + "\t(Total "

+ displayTotal + ")\n";

}

public double getTotal() {

double total = 0;

for (int i = 0; i < marks.size(); i++) {

total = total + marks.get(i);

}

return total;

}

public double getMark(int index) {

return marks.get(index);

}

/** DO NOT MODIFY

*

* @return name of the student */

public String getName() {

return name;

}

/** DO NOT MODIFY

*

* @return id */

public int getId() {

return id;

}

/** DO NOT MODIFY

*

* @return number of assessments */

public int numberOfAssessments() {

return marks.size();

}

/** set the instance variable id to the parameter provided. if i is less than

* 1, id should become 1. otherwise, id should become i.

*

* @param i */

private void setId(int i) {

if (i < 1) {

id = 1;

} else {

id = i;

}

}

/** set instance variables name, id and marks to corresponding parameter

* provided. use the setter to set the id. you should make a deep copy for

* marks, NOT A SHALLOW COPY

*

* @param name

* @param id

* @param marks */

public GradebookEntry(String name, int id, ArrayList<Double> marks) {

this.name = name;

this.setId(id);

//this.marks = marks;

this.marks = makeDeepCopyInteger(marks);

// Stuck on setting marks, there is no setMarks method either

}

private ArrayList<Double> makeDeepCopyInteger(ArrayList<Double> old) {

ArrayList<Double> copy = new ArrayList<Double>(old.size());

for (Double i : old) {

copy.add(new Double(i));

}

return copy;

}

}

TestGradebookEntry.java

import static org.junit.Assert.*;

import java.util.ArrayList;

import java.util.Arrays;

import org.junit.Test;

import com.gradbook.GradebookEntry;

public class TestGradebookEntry {

@Test

public void testGradebookEntry() {

GradebookEntry entry = new GradebookEntry("Joshua Lyman", 5,

new ArrayList<Double>(Arrays.asList(1.5, 4.5, 2.5, 8.5)));

assertEquals("Joshua Lyman", entry.getName());

assertEquals(5, entry.getId());

assertEquals(4, entry.numberOfAssessments());

assertEquals(1.5, entry.getMark(0), 0.0001);

assertEquals(4.5, entry.getMark(1), 0.0001);

assertEquals(2.5, entry.getMark(2), 0.0001);

assertEquals(8.5, entry.getMark(3), 0.0001);

}

}

Output:

R Markers Prope.. 娏Servers -Cons." 滮Datas.. E Snipp Progr ィSearch凶Git St f History杵Debug Devel. 궈 Call H สุโ JUnit X -O Finished after 0.008 seconds Runs: 11 E3 Errors: 0 Failures: 0 4 com.selenium.TestGradebookEntry [Runner: JUnit 4] (0.000 s) = Failure Trace testGradebookEntry (0.000 s)