We Keep Coding

How do you put integers within a range in Java?

Though I am sure that this answer is simple, I am not sure that is asked of me for this assignment. Here is the full code that I have written (so just a return!) as well as the instructions that were given:
package code;
/**
* This class contains a variety of methods that will be used throughout the Ratings and Reviews
* project.
*/
public class Utilities{
/**
* Computes the average of two ratings
*
* #param rating0 An integer rating in the range of 1-5 inclusive
* #param rating1 An integer rating in the range of 1-5 inclusive
* #return the average of rating0 and rating1 as a double
*/
public double averageRating(int rating0, int rating1){
return ((rating0 + rating1) / 2); // Don't forget to replace this return statement with your own
}
Sorry for bad structure upon pasting it. I think my return is suitable for what is being done, provided that the rating could be just anything. I know that it can only be between 1-5, though, so how would one go about specifying that?

How about throwing an InvalidArgumentException if the range is violated?
e.g.
public double averageRating(int rating0, int rating1){
if (rating0 < 1 || rating0 > 5 || rating1 < 1 || rating1 > 5) {
throw new InvalidArgumentException("Rating out of range");
}
return ((rating0 + rating1) / 2.0); // Don't forget to replace this return statement with your own
}

Getting the unicode value of the first character in a string

I am basically being asked to take the Unicode value of a string, multiply it by 10% and add whatever level the object currently has. It's frustrating because as it turns out I have the logic down including the code yet I still get an error that says: expected:<0> but was:<8>. Any suggestions, maybe it's just a slight nuance I have to make in the logic, although I'm fairly certain it's right. Take note of the getLevel method because that's where the error is
public class PouchCreature implements Battleable {
private String name;
private int strength;
private int levelUps;
private int victoriesSinceLevelUp;
/**
* Standard constructor. levelUps and victoriesSinceLevelUp start at 0.
*
* #param nameIn desired name for this PouchCreature
* #param strengthIn starting strength for this PouchCreature
*/
public PouchCreature(String nameIn, int strengthIn) {
this.name = nameIn;
this.strength = strengthIn;
this.levelUps = 0;
this.victoriesSinceLevelUp = 0;
}
/**
* Copy constructor.
*
* #param other reference to the existing object which is the basis of the new one
*/
public PouchCreature(PouchCreature other) {
this.name=other.name;
this.strength=other.strength;
this.levelUps=other.levelUps;
this.victoriesSinceLevelUp=other.victoriesSinceLevelUp;
}
/**
* Getter for skill level of the PouchCreature, which is based on the
* first character of its name and the number of levelUps it has.
* Specifically, the UNICODE value of the first character in its name
* taken %10 plus the levelUps.
*
* #return skill level of the PouchCreature
*/
public int getLevel() {
int value = (int)((int)(getName().charAt(0)) * 0.1);
return value + this.levelUps;
}

You've said you're supposed to increase the value by 10%. What you're actually doing, though, is reducing it 90% by taking just 10% of it (and then truncating that to an int). 67.0 * 0.1 = 6.7, which when truncated to an int is 6.
Change the 0.1 to 1.1 to increase it by 10%:
int value = (int)((int)(getName().charAt(0)) * 1.1);
// --------------------------------------------^
There, if getName() returns "Centaur" (for instance), the C has the Unicode value 67, and value ends up being 73.

We need to see the code you're calling the class with and that is generating your error message. Why is it expecting 0? 8 seems like a valid return value from the information you've given.

For each loop set value

Running into a problem. I have two methods with for each loops that calculates executives pay either by percentage or base pay. In my Executive class I have my pay method that takes base pay rate and multiplies with bonus. This works if it's percentage but if its base pay and call this method doesn't work.
Do I have put a if statement in my executive class to see if it's percentage or base pay?
Staff Class
/**
* Assigns the specified flat value weekly bonus to the Executives.
*
* #param bonusValue
* as a double, i.e., $1,000 = 1000.0
*/
public void setExecutiveBonusFlatRate(double bonusValue) {
for (StaffMember executiveEmployee : staffList) {
if (executiveEmployee instanceof Executive) {
((Executive) executiveEmployee).setBonus(bonusValue);
}
}
}
/**
* Assigns the specified percentage weekly bonus to the Executives.
*
* #param bonus
* as a percentage, i.e., 20% = 0.2
*/
public void setExecutiveBonusPercentage(double bonusPercentage) {
for (StaffMember executiveEmployee : staffList) {
if (executiveEmployee instanceof Executive) {
((Executive) executiveEmployee).setBonus(bonusPercentage);
}
}
}
/**
* Pays all the staff members.
*/
public void payday() {
for (StaffMember allEmployee : staffList) {
allEmployee.toString();
System.out.println(allEmployee.pay());
System.out.println(allEmployee.toString());
}
}
From Executive class extended from Employee
/** #overide
* return the weekly payrate plus the bonus
*/
public double pay() {
double payment = payRate * bonus;
bonus = 0;
return payment;

We need to correct two things here:
setExecutiveBonusPercentage should set the bonus as base * percentage * 0.01 to be consistent with bonusValue set in setExecutiveBonusFlatRate as we have no way to know whether bonus is a value or percentage.
In pay() method, we are setting bonus to 0 (bonus = 0;) which needs to be removed as it resets the bonus value. Due to this, first call of pay() will return correct result whereas subsequent calls will return 0.

Query on clarification about toOcean() method

This query can be answered only after going through the history of previous query where the Part I of the solution is discussed.
Following is the solution, I wrote for Part IIa and PartIIb, I need clarification before writing PartIIc i.e., toOcean() method.
/* RunLengthEncoding.java */
package Project1;
/**
* The RunLengthEncoding class defines an object that run-length encodes an
* Ocean object. Descriptions of the methods you must implement appear below.
* They include constructors of the form
*
* public RunLengthEncoding(int i, int j, int starveTime);
* public RunLengthEncoding(int i, int j, int starveTime,
* int[] runTypes, int[] runLengths) {
* public RunLengthEncoding(Ocean ocean) {
*
* that create a run-length encoding of an Ocean having width i and height j,
* in which sharks starve after starveTime timesteps.
*
* The first constructor creates a run-length encoding of an Ocean in which
* every cell is empty. The second constructor creates a run-length encoding
* for which the runs are provided as parameters. The third constructor
* converts an Ocean object into a run-length encoding of that object.
*
* See the README file accompanying this project for additional details.
*/
class RunLengthEncoding {
/**
* Define any variables associated with a RunLengthEncoding object here.
* These variables MUST be private.
*/
private DList2 list;
private int sizeOfRun;
private int width;
private int height;
private int starveTime;
/**
* The following methods are required for Part II.
*/
/**
* RunLengthEncoding() (with three parameters) is a constructor that creates
* a run-length encoding of an empty ocean having width i and height j,
* in which sharks starve after starveTime timesteps.
* #param i is the width of the ocean.
* #param j is the height of the ocean.
* #param starveTime is the number of timesteps sharks survive without food.
*/
public RunLengthEncoding(int i, int j, int starveTime) {
this.list = new DList2();
this.list.insertFront(TypeAndSize.Species.EMPTY, i*j);
this.sizeOfRun = 1;
this.width = i;
this.height = j;
this.starveTime = starveTime;
}
/**
* RunLengthEncoding() (with five parameters) is a constructor that creates
* a run-length encoding of an ocean having width i and height j, in which
* sharks starve after starveTime timesteps. The runs of the run-length
* encoding are taken from two input arrays. Run i has length runLengths[i]
* and species runTypes[i].
* #param i is the width of the ocean.
* #param j is the height of the ocean.
* #param starveTime is the number of timesteps sharks survive without food.
* #param runTypes is an array that represents the species represented by
* each run. Each element of runTypes is Ocean.EMPTY, Ocean.FISH,
* or Ocean.SHARK. Any run of sharks is treated as a run of newborn
* sharks (which are equivalent to sharks that have just eaten).
* #param runLengths is an array that represents the length of each run.
* The sum of all elements of the runLengths array should be i * j.
*/
public RunLengthEncoding(int i, int j, int starveTime,
TypeAndSize.Species[] runTypes, int[] runLengths) {
this.list = new DList2();
this.sizeOfRun = 0;
this.width = i;
this.height = j;
this.starveTime = starveTime;
if(runTypes.length != runLengths.length){
System.out.println("lengths are unequal");
}else{
for(int index=0; index < runTypes.length; index++){
this.list.insertFront(runTypes[index], runLengths[index]);
this.sizeOfRun++;
}
}
}
/**
* restartRuns() and nextRun() are two methods that work together to return
* all the runs in the run-length encoding, one by one. Each time
* nextRun() is invoked, it returns a different run (represented as a
* TypeAndSize object), until every run has been returned. The first time
* nextRun() is invoked, it returns the first run in the encoding, which
* contains cell (0, 0). After every run has been returned, nextRun()
* returns null, which lets the calling program know that there are no more
* runs in the encoding.
*
* The restartRuns() method resets the enumeration, so that nextRun() will
* once again enumerate all the runs as if nextRun() were being invoked for
* the first time.
*
* (Note: Don't worry about what might happen if nextRun() is interleaved
* with addFish() or addShark(); it won't happen.)
*/
/**
* restartRuns() resets the enumeration as described above, so that
* nextRun() will enumerate all the runs from the beginning.
*/
public void restartRuns() {
this.sizeOfRun = 0;
}
/**
* nextRun() returns the next run in the enumeration, as described above.
* If the runs have been exhausted, it returns null. The return value is
* a TypeAndSize object, which is nothing more than a way to return two
* integers at once.
* #return the next run in the enumeration, represented by a TypeAndSize
* object.
*/
public TypeAndSize nextRun() {
TypeAndSize obj = null;
if(this.sizeOfRun > 0){
obj = this.list.nTh(this.sizeOfRun);
this.sizeOfRun--;
}
return obj;
}
}
==========
/* DList2.java */
package Project1;
/**
* A DList2 is a mutable doubly-linked list. Its implementation is
* circularly-linked and employs a sentinel (dummy) node at the sentinel
* of the list.
*/
class DList2 {
/**
* sentinel references the sentinel node.
*
* DO NOT CHANGE THE FOLLOWING FIELD DECLARATIONS.
*/
protected DListNode2 sentinel;
protected long size;
/* DList2 invariants:
* 1) sentinel != null.
* 2) For any DListNode2 x in a DList2, x.next != null.
* 3) For any DListNode2 x in a DList2, x.prev != null.
* 4) For any DListNode2 x in a DList2, if x.next == y, then y.prev == x.
* 5) For any DListNode2 x in a DList2, if x.prev == y, then y.next == x.
* 6) size is the number of DListNode2s, NOT COUNTING the sentinel
* (denoted by "sentinel"), that can be accessed from the sentinel by
* a sequence of "next" references.
*/
/**
* DList2() constructor for an empty DList2.
*/
public DList2() {
this.sentinel = new DListNode2();
this.sentinel.next = this.sentinel;
this.sentinel.prev = this.sentinel;
this.size = 0;
}
/**
* insertFront() inserts an object of type TypeAndSizeAndHungerAndStarveTime at the front of a DList2.
*/
void insertFront(TypeAndSize.Species runType, int runLength) {
DListNode2 newNode = new DListNode2(runType, runLength);
newNode.next = this.sentinel.next;
this.sentinel.next.prev = newNode;
this.sentinel.next = newNode;
this.sentinel.next.prev = this.sentinel;
this.size++;
}
/**
* nTh() returns the nTh node
* #param nTh
* #return
*/
TypeAndSize nTh(int nTh){
DListNode2 node = this.sentinel.prev;
int index = 1;
while(index < nTh ){
node = node.prev;
}
return node.runObject;
}
}
============================
/* DListNode2.java */
package Project1;
/**
* A DListNode2 is a node in a DList2 (doubly-linked list).
*/
class DListNode2 {
/**
* item references the item stored in the current node.
* prev references the previous node in the DList.
* next references the next node in the DList.
*
* DO NOT CHANGE THE FOLLOWING FIELD DECLARATIONS.
*/
TypeAndSize runObject;
DListNode2 prev;
DListNode2 next;
/**
* DListNode2() constructor.
*/
DListNode2() {
this.runObject = null;
this.prev = null;
this.next = null;
}
DListNode2(TypeAndSize.Species runType, int runLength) {
this.runObject = new TypeAndSize(runType, runLength);
this.prev = null;
this.next = null;
}
}
===================================
/* TypeAndSize.java */
/* DO NOT CHANGE THIS FILE. */
/* YOUR SUBMISSION MUST WORK CORRECTLY WITH _OUR_ COPY OF THIS FILE. */
package Project1;
/**
* Each TypeAndSize object represents a sequence of identical sharks, fish,
* or empty cells. TypeAndSizes are your way of telling the test program
* what runs appear in your run-length encoding. TypeAndSizes exist solely
* so that your program can return two integers at once: one representing
* the type (species) of a run, and the other representing the size of a run.
*
* TypeAndSize objects are not appropriate for representing your run-length
* encoding, because they do not represent the degree of hunger of a run of
* sharks.
*
* #author Jonathan Shewchuk
*/
class TypeAndSize {
Species type; // runType EMPTY, SHARK, or FISH
int size; // Number of cells in the run for that runType.
enum Species{EMPTY,SHARK,FISH}
/**
* Constructor for a TypeAndSize of specified species and run length.
* #param species is Ocean.EMPTY, Ocean.SHARK, or Ocean.FISH.
* #param runLength is the number of identical cells in this run.
* #return the newly constructed Critter.
*/
TypeAndSize(Species species, int runLength) {
if (species == null) {
System.out.println("TypeAndSize Error: Illegal species.");
System.exit(1);
}
if (runLength < 1) {
System.out.println("TypeAndSize Error: runLength must be at least 1.");
System.exit(1);
}
this.type = species;
this.size = runLength;
}
}
======================================
For reference, complete skeleton of code for assignment is given in link
In the given link, following paragraph says:
Part II(c): Implement a toOcean() method in the RunLengthEncoding class, which converts a run-length encoding to an Ocean object. To accomplish this, you will need to implement a new addShark() method in the Ocean class, so that you can specify the hunger of each shark you add to the ocean. This way, you can convert an Ocean to a run-length encoding and back again without forgetting how hungry each shark was.
My question:
In PartIIa and PartIIb of the solution written in RunLenghtEncoding() 5 argument constructor, I am not capturing hungerLevel property of Shark due to the reason mentioned in method comments -
Any run of sharks is treated as a run of newborn sharks (which are equivalent to sharks that have just eaten).
I would like to know, What exactly toOcean() method mean, when. i do not capture hungerLevel of Shark runType. Am I suppose to convert the Compressed form of Ocean to an 'existing Ocean' or 'new Ocean'? Please help me, am stuck here.
Note: This is self learning course published in 2006. No mentor available for this course. Also suggest me, if this is the right place to discuss such queries

It says that
Any run of sharks is treated as a run of newborn sharks (which are equivalent to sharks that have just eaten).
So when you have to re-create the Ocean, you can treat any run of sharks as sharks with hungerLevel 0. In Part III you do have to keep track of the hungerLevel, however. But for Part II c they leave that out for the moment being.

Public class DiscoLight help

If some one can point me in the right direction for this code for my assigment I would really appreciate it.
I have pasted the whole code that I need to complete but I need help with the following method public void changeColour(Circle aCircle) which is meant to allow to change the colour of the circle randomly, if 0 comes the light of the circle should change to red, 1 for green and 2 for purple.
public class DiscoLight
{
/* instance variables */
private Circle light; // simulates a circular disco light in the Shapes window
private Random randomNumberGenerator;
/**
* Default constructor for objects of class DiscoLight
*/
public DiscoLight()
{
super();
this.randomNumberGenerator = new Random();
}
/**
* Returns a randomly generated int between 0 (inclusive)
* and number (exclusive). For example if number is 6,
* the method will return one of 0, 1, 2, 3, 4, or 5.
*/
public int getRandomInt(int number)
{
return this.randomNumberGenerator.nextInt(number);
}
/**
* student to write code and comment here for setLight(Circle) for Q4(i)
*/
public void setLight(Circle aCircle)
{
this.light = aCircle;
}
/**
* student to write code and comment here for getLight() for Q4(i)
*/
public Circle getLight()
{
return this.light;
}
/**
* Sets the argument to have a diameter of 50, an xPos
* of 122, a yPos of 162 and the colour GREEN.
* The method then sets the receiver's instance variable
* light, to the argument aCircle.
*/
public void addLight(Circle aCircle)
{
//Student to write code here, Q4(ii)
this.light = aCircle;
this.light.setDiameter(50);
this.light.setXPos(122);
this.light.setYPos(162);
this.light.setColour(OUColour.GREEN);
}
/**
* Randomly sets the colour of the instance variable
* light to red, green, or purple.
*/
public void changeColour(Circle aCircle)
{
//student to write code here, Q4(iii)
if (getRandomInt() == 0)
{
this.light.setColour(OUColour.RED);
}
if (this.getRandomInt().equals(1))
{
this.light.setColour(OUColour.GREEN);
}
else
if (this.getRandomInt().equals(2))
{
this.light.setColour(OUColour.PURPLE);
}
}
/**
* Grows the diameter of the circle referenced by the
* receiver's instance variable light, to the argument size.
* The diameter is incremented in steps of 2,
* the xPos and yPos are decremented in steps of 1 until the
* diameter reaches the value given by size.
* Between each step there is a random colour change. The message
* delay(anInt) is used to slow down the graphical interface, as required.
*/
public void grow(int size)
{
//student to write code here, Q4(iv)
}
/**
* Shrinks the diameter of the circle referenced by the
* receiver's instance variable light, to the argument size.
* The diameter is decremented in steps of 2,
* the xPos and yPos are incremented in steps of 1 until the
* diameter reaches the value given by size.
* Between each step there is a random colour change. The message
* delay(anInt) is used to slow down the graphical interface, as required.
*/
public void shrink(int size)
{
//student to write code here, Q4(v)
}
/**
* Expands the diameter of the light by the amount given by
* sizeIncrease (changing colour as it grows).
*
* The method then contracts the light until it reaches its
* original size (changing colour as it shrinks).
*/
public void lightCycle(int sizeIncrease)
{
//student to write code here, Q4(vi)
}
/**
* Prompts the user for number of growing and shrinking
* cycles. Then prompts the user for the number of units
* by which to increase the diameter of light.
* Method then performs the requested growing and
* shrinking cycles.
*/
public void runLight()
{
//student to write code here, Q4(vii)
}
/**
* Causes execution to pause by time number of milliseconds
*/
private void delay(int time)
{
try
{
Thread.sleep(time);
}
catch (Exception e)
{
System.out.println(e);
}
}
}

You have forgotten to pass a parameter when calling getRandomInt() in the very first line below //student to write code here. Your compiler should already point this out, though.
The documentation comment above the getRandomInt() method tells you what it expects as parameter, and what you can expect as return value.
Also, if you want equal chances that the lamp is red, green or purple, you should be able to do that with a single invocation of getRandomInt(). Store the value in a variable, and use a switch statement to turn on the correct light:
int randomValue = getRandomInt(/* I am not telling you what to put here */);
switch (randomValue) {
case 0: light.setColour(OUColour.RED); break;
case 1: light.setColour(OUColour.GREEN); break;
case 2: light.setColour(OUColour.PURPLE); break;
}

/**
* Randomly sets the colour of the instance variable
* light to red, green, or purple.
*/
public void changeColour(Circle aCircle)
{
int i = getRandomInt(3);
if (i == 0)
{
this.light.setColour(OUColour.RED);
}
else if (i == 1)
{
this.light.setColour(OUColour.GREEN);
}
else
{
this.light.setColour(OUColour.PURPLE);
}
}

the method getRandomInt returns an int, so you can't use equals to compare. use:
if (getRandomInt(3) == 1) {
...
}
and you just need to call it once. store the random integer in a variable and compare its value with the ones you want.

you're calling getRandomInt several times, with each time a new (random) value returned.
you should call it once at the begin of the method, and then check if it is 0,1 or 2.
Regards
Guillaume