Develop Reference

I don't know how to do an array to store for each semester the details. I am supposed to create a subclass of the class Student

The question wants me to do:
An array of Finance called financeRecord to store the details
of the payments for each semester.
This is my code
package lab5;
class Student_U extends Student {
public String student_name;
private String studentID;
public int student_age;
private byte currentSemester;
private byte TotalFinanceRecord;
private String cohort;
public Student_U() {
student_name = " ";
studentID = " ";
student_age = 0;
currentSemester = 1;
TotalFinanceRecord = 0;
cohort = " ";
}
public Student_U(String student_name, String studentID, int student_age,
String course, String year,
String section, String subject, String student_name2,
String studentID2, int student_age2,
byte currentSemester, byte totalFinanceRecord, String cohort) {
super(student_name, studentID, student_age, course, year,
section, subject);
student_name = student_name2;
studentID = studentID2;
student_age = student_age2;
this.currentSemester = currentSemester;
TotalFinanceRecord = totalFinanceRecord;
this.cohort = cohort;
}
public String getStudent_name() {
return student_name;
}
public void setStudent_name(String student_name) {
this.student_name = student_name;
}
public String getStudentID() {
return studentID;
}
public void setStudentID(String studentID) {
this.studentID = studentID;
}
public int getStudent_age() {
return student_age;
}
public void setStudent_age(int student_age) {
this.student_age = student_age;
}
public byte getCurrentSemester() {
return currentSemester;
}
public void setCurrentSemester(byte currentSemester) {
this.currentSemester = currentSemester;
}
public byte getTotalFinanceRecord() {
return TotalFinanceRecord;
}
public void setTotalFinanceRecord(byte totalFinanceRecord) {
TotalFinanceRecord = totalFinanceRecord;
}
public String getCohort() {
return cohort;
}
public void setCohort(String cohort) {
this.cohort = cohort;
}
public void initStudent() {
}
public void print() {
System.out.print("Student name: " + student_name + " ");
System.out.print("\nMatric No: " + studentID + " ");
System.out.print("\nAge: " + student_age + " ");
System.out.print("\nCurrent Semester: " + currentSemester + " ");
System.out.print("\nCohort: " + cohort + " ");
System.out.println();
}
}
Please help me fix my code I would appreciate it so much.
This is my lab assignment which needs to be submitted by tomorrow.

You could try this, but it's also better to review standard java concepts (arrays, classes, etc). After, just adapt your code as suitable.
public class Finance extends Student
{
public static void main(String args[])
{
Finance f1 = new Finance("Student_1");
System.out.println(f1);
f1.setPayment(1, 10);
System.out.println(f1);
f1.setPayment(2, 10.77);
System.out.println(f1);
Student s2 = new Student("Student 2");
Finance f2 = new Finance(s2);
f2.setPayment(2, 88.77);
System.out.println(f2);
}
Double finaceRecord[] = new Double[3];
private void initPayment()
{
for(int i=0;i<finaceRecord.length;i++)
{
finaceRecord[i]=0.0;
}
}
public Finance(Student s)
{
super(s.name);
initPayment();
}
public Finance(String name)
{
super(name);
initPayment();
}
//store first or second
public void setPayment(int i, double d)
{
if(d<=0) return;
if(i==1)
{
finaceRecord[i] = d;
}
else
{
finaceRecord[2] = d;
}
finaceRecord[0] = finaceRecord[2] + finaceRecord[1];
}
public String toString()
{
return "name="+super.name+", Total Paid="+finaceRecord[0]+","
+ " Sem1="+finaceRecord[1]+", Sem2="+finaceRecord[2];
}
}
...
public class Student
{
String name;
int Semester;
Student(String name)
{
this.name = name;
this.Semester = 1;
}
}
Ouptut
name=Student_1, Total Paid=0.0, Sem1=0.0, Sem2=0.0
name=Student_1, Total Paid=10.0, Sem1=10.0, Sem2=0.0
name=Student_1, Total Paid=20.77, Sem1=10.0, Sem2=10.77
name=Student 2, Total Paid=88.77, Sem1=0.0, Sem2=88.77

from what I understand you are supposed to create an array of Finance type
Finance []financeRecord = new Finance[totalFinanceRecord];
and then you can access the values of Finance class
financeRecord[indexNumber].methodName();

Calling a parametrized method from LibraryCollection class to main Class

I am working on library management system project. Below is my LibraryCollection class. I would like to call my findMaterials() and checkOutMaterial() methods in the main class.
I have been trying to call as in below method but I don't get any value in the console.
public static LibraryCollection librarycollectObj1 = new LibraryCollection(10);
String search = null;
librarycollectObj1.findMaterial(search);
Thanks;
//LibraryCollection Class
public class LibraryCollection
{
private int collectionMaxSize;
private Material[] libraryCollection;
public LibraryCollection(int theMaxSize)
{
collectionMaxSize = theMaxSize;
libraryCollection = new Material[collectionMaxSize];
}
public LibraryCollection(int theCollectSize, Material[] theArray)
{
collectionMaxSize = theCollectSize;
libraryCollection = theArray;
}
//(1)----------------Find MATERIAL-----------------
public Material findMaterial(String theFindMaterial)
{
if(theFindMaterial == null)
{
return null;
}
for(int i = 0; i < libraryCollection.length; i++)
{
if(libraryCollection[i] !=null && theFindMaterial.equals(libraryCollection[i].getMaterialId()))
{
return libraryCollection[i];
}
}
return null;
}
//Material ID & checkedOutPtron ID;
public boolean checkOutMaterial(String matrlID, String patronId)
{
Material thisMaterial = findMaterial(matrlID);
if(thisMaterial == null)
{
System.out.println("The material doesn't exist" );
return false;
}
if(thisMaterial.checkedOut())
{
System.out.println("The material has been already checked out " );
return false;
}
thisMaterial.setCheckedOut(true);
thisMaterial.setPatronCheckout(Integer.parseInt(patronId));//Convert string value into int
return true;
}
//Material Class
public class Material
{
private static int materialID = 0 ;
private int mtrId;
private String title;
private boolean checkedOut ;
private int checkedOutPatron;
public Material()
{
mtrId = 0;
title = "";
checkedOut = false;
checkedOutPatron = 0;
}
public Material(int theId, String theTitle)
{
mtrId = theId;
title = theTitle;
}
//Getter Method
public String getMaterialId()
{
return mtrId + "";
}
public String getTitle()
{
return title;
}
public void setCheckedOut(boolean theCheckout)
{
checkedOut = theCheckout;
}
public void setPatronCheckout(int patronCheckout)
{
checkedOutPatron = patronCheckout;
}
public boolean checkedOut()
{
return checkedOut;
}
public int getCheckedOutPatron()
{
return checkedOutPatron;
}
//ToString Method
public String toString()
{
return " \nMaterial ID: " + mtrId + " \nMaterial Title: " + title + " \nChecked Out: "
+ checkedOut + " \nPatron check out: " + checkedOutPatron;
}
public static int getNextID()
{
materialID++;
return materialID;
}
}

When you run:
String search = null
librarycollectObj1.findMaterial(search);
You execute
public Material findMaterial(String theFindMaterial)
{
if(theFindMaterial == null)
{
return null;
}
Since theFindMaterial = search and search = null then you exit the method without doing anything because theFindMaterial = null.
You could do something like this:
public static LibraryCollection librarycollectObj1 = new LibraryCollection(10);
// Initialize the object somehow
for (int i = 0; i < 10; i++) {
librarycollectObj1.libraryCollection[i] = new Material(i, "");
}
String search = "1";
// Do some null checking in production code
System.out.println(librarycollectObj1.findMaterial(search). getMaterialId());

Call non static methods from another class in constructor

I have a car class and its constructor looks like this:
public Cars(String carID, String plateNum, String position, Attendant assignedTo, long currTime) {
this.carID = carID;
this.plateNum = plateNum;
this.position = position;
this.assignedTo = assignedTo;
this.currTime = currTime;
}
The constructor is initialized in another class(main) when I press for create car from the menu.
The parameters of the constructor are all created/initiated by methods in the car class. The system should be the one giving the information like(the ID, position and time in).
The problem is that the car object have not be initialized yet so I can't get the methods to work.
But I really need the cars object to contain its information(like car ID:CR1).
The information are all strings except for the time.
How can I do that?
PS: Im new to programming. At first I was using static but it turns out static methods cause another bigger trouble with my code.
I posted something where there was my static methods and everyone told me to remove the statics.
public void addCar() {
Cars car1 = new Cars(car1.getID(), car1.askCarID(), Cars.getPosition(), Attendant.askForAtt(), System.currentTimeMillis());
myGarage.add(car1);
if(!(car1.getAssignedTo()).equals(null)){
car1.getAssignedTo().setAssign(car1);
car1.getAssignedTo().setAvailable(false);
}
}
This is what is called when I want to create a new car.
I also put the whole car class in case you need it:
import java.util.ArrayList;
import java.util.Scanner;
import java.util.concurrent.TimeUnit;
import javax.swing.text.Position;
public class Cars {
private String carID;
private String plateNum;
private String position;
private Attendant assignedTo;
private long currTime;
static ArrayList<String> tempArray2 = new ArrayList<String>();
public Cars(String carID, String plateNum, String position, Attendant assignedTo, long currTime) {
this.carID = carID;
this.plateNum = plateNum;
this.position = position;
this.assignedTo = assignedTo;
this.currTime = currTime;
}
public void createCarsID() {
for (int x = 0; x < Garage.getCarsCapacity(); x++) {
String tempCarID = ("CR" + (x + 1));
tempArray2.add(tempCarID);
}
}
public String getID() {
createCarsID();
String tempID = null;
String tempPos = null;
for (int x = 0; x < Garage.getCarsCapacity(); x++) {
if (tempArray2.get(x) != null) {
tempID = tempArray2.get(x);
tempPos = tempArray2.get(x);
tempArray2.remove(tempArray2.get(x));
getPos(tempPos);
//tempArray2.get(x) = null;
break;
}
}
return tempID;
}
public static void getPos(String IdToPos) {
String strPos = IdToPos.substring(2);
int pos = Integer.parseInt(strPos);
position = "GR" + pos;
}
public String getPlateNum() {
return plateNum;
}
public static String getCarID() {
return carID;
}
public static String getPosition() {
return position;
}
public long getCurrTime() {
return currTime;
}
public Attendant getAssignedTo() {
return assignedTo;
}
public static String askCarID() {
boolean valid = false;
System.out.println("Please enter your car's plate number.");
Scanner scanCarID = new Scanner(System.in);
String scannedCarID = scanCarID.nextLine();
while (!valid) {
if (scannedCarID.matches("^[A-Za-z][A-Za-z] [0-9][0-9][0-9]$")) {
valid = true;
System.out.println(scannedCarID);
} else {
System.out.println("Please enter a valid plate number. Ex: AF 378");
askCarID();
}
}
return scannedCarID.toUpperCase();
}
public String convert(long miliSeconds) {
int hrs = (int) TimeUnit.MILLISECONDS.toHours(miliSeconds) % 24;
int min = (int) TimeUnit.MILLISECONDS.toMinutes(miliSeconds) % 60;
int sec = (int) TimeUnit.MILLISECONDS.toSeconds(miliSeconds) % 60;
return String.format("%02d:%02d:%02d", hrs, min, sec);
}
#Override
public String toString() {
return "Car:" + plateNum + " ID:" + carID + " Position:" + position + " Assigned to:" + assignedTo.getId()
+ "(" + assignedTo.getName() + ")" + " Parked at:" + convert(currTime);
}
}

I attach you a code that can help you:
first as all the parameters can be statics i move then to the constructor.
second i move the static method "createCarsID();" to a static init block, in order to avoid unwanted calls.
The example is fully functional.
package test;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.concurrent.TimeUnit;
import javax.swing.text.Position;
public class Cars {
private String carID;
private String plateNum;
private String position;
private Attendant assignedTo;
private long currTime;
static ArrayList<String> tempArray2 = new ArrayList<String>();
static{
createCarsID();
}
public Cars() {
this.carID = Cars.getID();
this.plateNum = Cars.askCarID();
this.position = Cars.generatePosition();
this.assignedTo = Attendant.askForAtt();
this.currTime = System.currentTimeMillis();
}
public static void createCarsID() {
for (int x = 0; x < Garage.getCarsCapacity(); x++) {
String tempCarID = ("CR" + (x + 1));
tempArray2.add(tempCarID);
}
}
public static String getID() {
String tempID = null;
String tempPos = null;
for (int x = 0; x < Garage.getCarsCapacity(); x++) {
if (tempArray2.get(x) != null) {
tempID = tempArray2.get(x);
tempPos = tempArray2.get(x);
//tempArray2.remove(tempArray2.get(x));
//getPos(tempPos);
//tempArray2.get(x) = null;
break;
}
}
return tempID;
}
public static String generatePosition() {
String tempID = null;
String tempPos = null;
for (int x = 0; x < Garage.getCarsCapacity(); x++) {
if (tempArray2.get(x) != null) {
tempID = tempArray2.get(x);
tempPos = tempArray2.get(x);
tempArray2.remove(tempArray2.get(x));
return getPos(tempPos);
//tempArray2.get(x) = null;
}
}
return null;
}
public static String getPos(String IdToPos) {
String strPos = IdToPos.substring(2);
int pos = Integer.parseInt(strPos);
return "GR" + pos;
}
public String getPlateNum() {
return plateNum;
}
public String getCarID() {
return carID;
}
public String getPosition() {
return position;
}
public long getCurrTime() {
return currTime;
}
public Attendant getAssignedTo() {
return assignedTo;
}
public static String askCarID() {
boolean valid = false;
System.out.println("Please enter your car's plate number.");
Scanner scanCarID = new Scanner(System.in);
String scannedCarID = scanCarID.nextLine();
while (!valid) {
if (scannedCarID.matches("^[A-Za-z][A-Za-z] [0-9][0-9][0-9]$")) {
valid = true;
System.out.println(scannedCarID);
} else {
System.out.println("Please enter a valid plate number. Ex: AF 378");
askCarID();
}
}
return scannedCarID.toUpperCase();
}
public String convert(long miliSeconds) {
int hrs = (int) TimeUnit.MILLISECONDS.toHours(miliSeconds) % 24;
int min = (int) TimeUnit.MILLISECONDS.toMinutes(miliSeconds) % 60;
int sec = (int) TimeUnit.MILLISECONDS.toSeconds(miliSeconds) % 60;
return String.format("%02d:%02d:%02d", hrs, min, sec);
}
#Override
public String toString() {
return "Car:" + plateNum + " ID:" + carID + " Position:" + position + " Assigned to:" + assignedTo.getId()
+ "(" + assignedTo.getName() + ")" + " Parked at:" + convert(currTime);
}
}
Finally in order to call this function:
package test;
public class main {
public static void main(String [] args){
main test = new main();
test.addCar();
}
public void addCar() {
Cars car1 = new Cars();
Garage myGarage = new Garage();
myGarage.add(car1);
if(!(car1.getAssignedTo()).equals(null)){
car1.getAssignedTo().setAssign(car1);
car1.getAssignedTo().setAvailable(false);
}
}
}

Polymorphism java loop error

I'm having a problem regarding a polymorphic invocation inside a loop.
I have an abstract class called Item that has two subclasses ClothingItem and SportItem and an abstract method called printBudgetGST(Items[] item) to return a string of an item with updated pricing which include tax.
Item Class :
public abstract class Item
{
private int code;
private double price;
private boolean isOnGST;
public Item()
{
}
public Item(int code,double price,boolean isOnGST)
{
this.code = code;
this.price = price;
this.isOnGST = isOnGST;
}
public void setGST(boolean isgst)
{
this.isOnGST = isgst;
}
public int getCode()
{
return code;
}
public boolean getIsOnGST()
{
return isOnGST;
}
public double getCurrentPrice()
{
return price;
}
public String toString() {
return "Item [code=" + code + ", price=" + price + ", isOnGST=" + isOnGST + "]";
}
public abstract String printBudgetGST(Item[] items);
}
ClothingItem class
public class ClothingItem extends Item
{
public ClothingItem(){
}
public ClothingItem(int code,double price,boolean isOnGST)
{
super(code,price,isOnGST);
}
#Override
public String printBudgetGST(Item[] item)
{
String stringitem ="";
for(int i=0;i<item.length;i++)
{
if(item[i].getIsOnGST()==true&&item[i].getCurrentPrice()<100.00)
{
double finalprice =(0.06*item[i].getCurrentPrice())+item[i].getCurrentPrice();
stringitem = stringitem + " " + "ClothingItem : " + item[i].getCode()+":"+"RM"+finalprice;
}
}
return stringitem;
}
}
SportsItem class:
public class SportsItem extends Item
{
public SportsItem(){
}
public SportsItem(int code,double price,boolean isOnGST)
{
super(code,price,isOnGST);
}
public String printBudgetGST(Item[] item)
{
String stringitem = "";
for(int i=0;i<item.length;i++)
{
if(item[i].getIsOnGST()==true &&item[i].getCurrentPrice()<150.00)
{
double finalprice =(0.06*item[i].getCurrentPrice())+item[i].getCurrentPrice();
stringitem = stringitem + "SportsItem : " + item[i].getCode()+":"+"RM"+finalprice;
}
}
return stringitem;
}
}
Test class :
public class Retail_Item
{
private Item[] itemList;
public Retail_Item()
{
itemList = new Item[10];
itemList[0] = new ClothingItem(10001,85,true);
itemList[1] = new ClothingItem(10002,150,false);
itemList[2] = new ClothingItem(10003,168,true);
itemList[3] = new ClothingItem(10004,43,true);
itemList[4] = new ClothingItem(10005,162,false);
itemList[5] = new SportsItem(10006,178,false);
itemList[6] = new SportsItem(10007,80,true);
itemList[7] = new SportsItem(10008,191,false);
itemList[8] = new SportsItem(10009,45,true);
itemList[9] = new SportsItem(10010,121,true);
}
public void printItem()
{
for(int i =0 ;i<itemList.length;i++)
{
if(itemList[i].getIsOnGST()==true && itemList[i].printBudgetGST(itemList).length()>0)
{
System.out.println(itemList[i].printBudgetGST(itemList));
}
}
}
}
public class TestRetailItem {
public static void main(String[] args)
{
Retail_Item ret = new Retail_Item();
ret.printItem();
}
}
OUTPUT :
The output should return a list of items which is on tax(GST) and with the updated pricing information like the example below

The problem is that you are passing to printBudgetGST the whole array of items and iterating over that array inside your implementations of printBudgetGST. Instead, you should remove that parameter and inside printBudgetGST you should simply call getCurrentPrice() and getCode() on this rather than on each item[i].
In addition, you are doing the check for maximum price (< 100 or < 150) inside the item subclasses but it's best to do this alongside the other checks in printItem. Because the max price depends on the subclass (SportsItem vs ClothinItem) I recommend you to create an abstract method boolean isOnBudget() in Item and implement accordingly in those two subclasses.
A fully fixed version of your code is
public abstract class Item {
private int code;
private double price;
private boolean isOnGST;
public Item()
{
}
public Item(int code,double price,boolean isOnGST)
{
this.code = code;
this.price = price;
this.isOnGST = isOnGST;
}
public void setGST(boolean isgst)
{
this.isOnGST = isgst;
}
public int getCode()
{
return code;
}
public boolean getIsOnGST()
{
return isOnGST;
}
public double getCurrentPrice()
{
return price;
}
public String toString() {
return "Item [code=" + code + ", price=" + price + ", isOnGST=" + isOnGST + "]";
}
public abstract String printBudgetGST();
public abstract boolean isOnBudget();
}
class ClothingItem extends Item {
public ClothingItem() {
}
public ClothingItem(int code, double price, boolean isOnGST) {
super(code, price, isOnGST);
}
#Override
public String printBudgetGST() {
String stringitem = "";
double finalprice = (0.06 * getCurrentPrice()) + getCurrentPrice();
stringitem = stringitem + " " + "ClothingItem : " + getCode() + ":" + "RM" + finalprice;
return stringitem;
}
#Override
public boolean isOnBudget() {
return getCurrentPrice() < 100.00;
}
}
class SportsItem extends Item {
public SportsItem() {
}
public SportsItem(int code, double price, boolean isOnGST) {
super(code, price, isOnGST);
}
public String printBudgetGST() {
String stringitem = "";
double finalprice = (0.06 * getCurrentPrice()) + getCurrentPrice();
stringitem = stringitem + "SportsItem : " + getCode() + ":" + "RM" + finalprice;
return stringitem;
}
#Override
public boolean isOnBudget() {
return getCurrentPrice() < 150.00;
}
}
class Retail_Item
{
private Item[] itemList;
public Retail_Item()
{
itemList = new Item[10];
itemList[0] = new ClothingItem(10001,85,true);
itemList[1] = new ClothingItem(10002,150,false);
itemList[2] = new ClothingItem(10003,168,true);
itemList[3] = new ClothingItem(10004,43,true);
itemList[4] = new ClothingItem(10005,162,false);
itemList[5] = new SportsItem(10006,178,false);
itemList[6] = new SportsItem(10007,80,true);
itemList[7] = new SportsItem(10008,191,false);
itemList[8] = new SportsItem(10009,45,true);
itemList[9] = new SportsItem(10010,121,true);
}
public void printItem() {
for(int i =0 ;i<itemList.length;i++) {
if(itemList[i].getIsOnGST()==true && itemList[i].printBudgetGST().length()>0 && itemList[i].isOnBudget())
{
System.out.println(itemList[i].printBudgetGST());
}
}
}
}
class TestRetailItem {
public static void main(String[] args) {
Retail_Item ret = new Retail_Item();
ret.printItem();
}
}

Method Chaining to Print in an Compostion model with arrays

I am a student working on a project creating classes with arrays to model composition. I have assume I have everything right so far but it seem that I am getting a problem with my print statement in the driver class. I am not sure if it about the way I am method chaining the two together. Any information would be thankful.
public class MyWord
{
private String word;
public MyWord(){
word = "Null";
}
public MyWord(String s){
word = s;
}
public String getWord(){
return word;
}
public void setWord(String w){
word = w;
}
public void print(){
System.out.println(word);
}
}
public class Page
{
private MyWord[] words = new MyWord[5];
private int pageNumber;
public Page(){
MyWord words[] = {} ;
pageNumber = 0;
}
public Page(MyWord[] a, int b){
words = a;
pageNumber = b;
}
public MyWord[] getWord(){
return words;
}
public int getPageNumber(){
return pageNumber;
}
public void setMyWord(MyWord[] a){
words = a;
}
public void setPageNumber(int b){
pageNumber = b;
}
public void print(){
System.out.print(" Page Number: " + pageNumber + " " + words);
}
}
public class Book
{
private Page[] p = new Page[5];
private String title;
public Book(){
Page[] p = {};
title = " ";
}
public Book(Page[] pa, String ti){
p = pa;
title = ti;
}
public Page[] getPage(){
return p;
}
public String getTitle(){
return title;
}
public void setPage(Page[] x){
p = x;
}
public void setTitle(String y){
title = y;
}
public void print(){
System.out.print("Book info:" + p + " " + title);
}
}
public class Series
{
private Book bookOne, bookTwo, bookThree;
private double price;
public Series(){
bookOne = null;
bookTwo = null;
bookThree = null;
price = 0;
}
public Series(Book one, Book two, Book three, double p){
bookOne = one;
bookTwo = two;
bookThree = three;
price = p;
}
public Book getBookTwo(){
return bookTwo;
}
public Book getBookOne(){
return bookOne;
}
public Book getBookThree(){
return bookThree;
}
public double getPrice(){
return price;
}
public void setBookOne(Book bookOne){
this.bookOne = bookOne;
}
public void setBookTwo(Book bookTwo){
this.bookTwo = bookTwo;
}
public void setBookThree(Book bookThree){
this.bookThree = bookThree;
}
public void setPrice(double price){
this.price = price;
}
public void print(){
System.out.println("Series info");
System.out.println("Book one:" + bookOne + " Book Two: " +bookTwo
+ " Book Three: " + bookThree + "Price: " + price);
}
}
public class Driver
{
public static void main(String args[]){
MyWord[] w1 = new MyWord[2];
w1[0] = new MyWord("Hello");
w1[1] = new MyWord("Hola");
Page[] p = new Page[2];
p[0] = new Page(w1, 20);
p.print();
}
}

p is of type Page[], i.e. "array of Page". And arrays don't have a print() method. So the statement p.print() doesn't compile (you should have said that in your question, and joined the exact error message).
To print all the pages of the array, you need to loop over the array:
for (Page page : p) {
page.print();
}
Please avoid single-letter variables, and use a plural form for arrays and collections: Page[] pages = new Page[2];