I've been having some issues with this program. I have to test out using a driver class each method, but I can't seem to understand what I should do when the parameters are strings.
I had an example for int parameters but the example never showed anything on string parameters and how to convert. Using null makes my driver class run but putting an int or string won't.
What can I do to convert this correctly, so it can display whatever I have in the no parameter constructor?
public class StudentListing
{
private String name;
private String number;
public StudentListing(String n, String num)
{
name = n;
number = num;
}
public StudentListing()
{
name = null;
number = null;
}
public String toString()
{
return("Name is " + name +
"\nNumber is " + number + "\n");
}
public void show()
{
System.out.println(toString());
}
public StudentListing Clone()
{
StudentListing clone = new StudentListing (name, number);
return clone;
}
public int compareTo(String targetKey)
{
return (name.compareTo(targetKey));
}
public void input()
{
name = JOptionPane.showInputDialog("Enter a name");
number = JOptionPane.showInputDialog("Enter a number");
}// end of StudentListing
}//end of class
public class StudentListingDriver
{
public static void main(String[] args)
{
StudentListing s1 = new StudentListing();
StudentListing s2 = new StudentListing(null,null);
System.out.println(s1);
s1.input();
StudentListing s3 = s2.clone();
s1.show();
}
}
You can have default values and make the no-args constructor call the other constructor.
Use Integer.parseInt(); to convert from a String to an Integer.
You also need to check the conversion for exceptions.
Like this:
public class StudentListing {
private String name;
private int number;
public StudentListing(String n, int num) {
name = n;
number = num;
}
public StudentListing() {
this("defaultName", 0);
}
public String toString() {
return ("Name is " + name + "\nNumber is " + number + "\n");
}
public void show() {
System.out.println(toString());
}
public StudentListing Clone() {
StudentListing clone = new StudentListing(name, number);
return clone;
}
public int compareTo(String targetKey) {
return (name.compareTo(targetKey));
}
public void input() {
name = JOptionPane.showInputDialog("Enter a name");
number = Integer
.parseInt(JOptionPane.showInputDialog("Enter a number"));
}
}
The tester:
public class StudentListingDriver {
public static void main(String[] args) {
StudentListing s1 = new StudentListing();
StudentListing s2 = new StudentListing(null, 0);
System.out.println(s1);
s1.input();
StudentListing s3 = s2.Clone();
s1.show();
}
}
Related
I'm creating an object of type Lightmode, which is a class.
There's also a Smartlamp class which is having a variable of custom data of type Lighmodes and I want to show my defined data type value over there.
I'm trying to create an object and then insert a string against my Lightmode data type which is showing error. I want to print like this:
Name: lamp1
Location: 3.1
Switched On: false
Mode: STANDARD
Here mode is lightmode datatype and I'm getting a problem over it.
...
public class LightModes
{
String NIGHT_MODE;
String SOFT_MODE;
String STANDARD_MODE;
public String getNIGHT_MODE() {
return NIGHT_MODE;
}
public void setNIGHT_MODE(String NIGHT_MODE) {
this.NIGHT_MODE = NIGHT_MODE;
}
public String getSOFT_MODE() {
return SOFT_MODE;
}
public void setSOFT_MODE(String SOFT_MODE) {
this.SOFT_MODE = SOFT_MODE;
}
public String getSTANDARD_MODE() {
return STANDARD_MODE;
}
public void setSTANDARD_MODE(String STANDARD_MODE) {
this.STANDARD_MODE = STANDARD_MODE;
}
public LightModes() {
this.NIGHT_MODE = "NIGHT";
this.STANDARD_MODE = "STANDARD";
this.SOFT_MODE = "SOFT";
}
}...
...package smart.home.app;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
public class Step5 {
public static void main(String[] args) throws IOException {
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
int size,mode;
int displayindex=1;
String name;
double location,temperature;
boolean status=false;
System.out.println("Enter number of size of Fridge you want to add.");
Scanner in = new Scanner(System.in);
size=in.nextInt();
// TODO code application logic here
SmartLamp[] smartLamp=new SmartLamp[size];// creating an array object of smartdevice class
//
for(int j=0;j<size;j++)
{
System.out.println("Enter Lamp name.");
name=input.readLine();
System.out.println("Enter Lamp Location.\\hint(1.1)");
Scanner devicelocation=new Scanner(System.in);
location=devicelocation.nextDouble();
System.out.println("Enter Lamp Mode.(1 for Night 2 for Soft 3 for Standard)");
Scanner lampmode=new Scanner(System.in);
mode=lampmode.nextInt();
System.out.println("Enter Lamp status.1 for ON, 0 for OFF.");
Scanner devicestatus=new Scanner(System.in);
int currentstatus=devicestatus.nextInt();
if(currentstatus==1)
{
status=true;
}
else if(currentstatus==0)
{
status=false;
}
LightModes light = null;
smartLamp[j]=new SmartLamp(light.NIGHT_MODE, name, location, status);
}
//////////////Display Data////////////////////////////
for(int i=0;i<size;i++)
{
System.out.println("-Smart lamp "+displayindex+" -");
System.out.println(smartLamp[i].toString());
System.out.println("---------------------------------------------");
displayindex++;
}
}
}...
...public class SmartLamp extends SmartDevice{
private LightModes lightModes;
public LightModes getLightModes() {
return lightModes;
}
public void setLightModes(LightModes lightModes) {
this.lightModes = lightModes;
}
public SmartLamp(String name, double location, boolean switchedOn) {
super(name, location, switchedOn);
}
public SmartLamp(LightModes lightModes, String name, double location, boolean switchedOn) {
super(name, location, switchedOn);
this.lightModes = lightModes;
}
#Override
public String toString() {
return "SmartLamp{"+"\nName."+getName()+"\nLocation."
+getLocation() + "\nSwitchedOn."+isSwitchedOn()+
"\nMode=" + getLightModes() + '}';
}
}...
I downloaded your code and added the missing class SmartDevice. Your code contains two compiler errors.
name = input.readLine();
This line throws java.io.IOException which is an unchecked exception and hence must be handled by your code. There are several ways to do this, one of which is to add throws IOException to method main() in class Step5.
smartLamp[j]=new SmartLamp(light.NIGHT_MODE, name, location, status);
The first argument to SmartLamp constructor is an instance of class LightModes but you are passing a String. You need to create an instance of LightModes.
Here is your code with my modifications that get rid of the two compiler errors.
(Note: The below code includes my guessed implementation of class SmartDevice.)
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
public class Step5 {
public static void main(String[] args) throws IOException { // Change here.
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
int size, mode;
int displayindex = 1;
String name;
double location, temperature;
boolean status = false;
System.out.println("Enter number of size of Fridge you want to add.");
Scanner in = new Scanner(System.in);
size = in.nextInt();
SmartLamp[] smartLamp = new SmartLamp[size];// creating an array object of smartdevice class
for (int j = 0; j < size; j++) {
System.out.println("Enter Lamp name.");
name = input.readLine(); // throws java.io.IOException
System.out.println("Enter Lamp Location.\\hint(1.1)");
Scanner devicelocation = new Scanner(System.in);
location = devicelocation.nextDouble();
System.out.println("Enter Lamp Mode.(1 for Night 2 for Soft 3 for Standard)");
Scanner lampmode = new Scanner(System.in);
mode = lampmode.nextInt();
System.out.println("Enter Lamp status.1 for ON, 0 for OFF.");
Scanner devicestatus = new Scanner(System.in);
int currentstatus = devicestatus.nextInt();
if (currentstatus == 1) {
status = true;
}
else if (currentstatus == 0) {
status = false;
}
LightModes light = new LightModes(); // Change here.
light.setNIGHT_MODE(light.getNIGHT_MODE()); // Change here.
smartLamp[j] = new SmartLamp(light, name, location, status); // Change here.
}
//////////////Display Data////////////////////////////
for(int i=0;i<size;i++)
{
System.out.println("-Smart lamp "+displayindex+" -");
System.out.println(smartLamp[i].toString());
System.out.println("---------------------------------------------");
displayindex++;
}
}
}
class LightModes {
String NIGHT_MODE;
String SOFT_MODE;
String STANDARD_MODE;
public String getNIGHT_MODE() {
return NIGHT_MODE;
}
public void setNIGHT_MODE(String NIGHT_MODE) {
this.NIGHT_MODE = NIGHT_MODE;
}
public String getSOFT_MODE() {
return SOFT_MODE;
}
public void setSOFT_MODE(String SOFT_MODE) {
this.SOFT_MODE = SOFT_MODE;
}
public String getSTANDARD_MODE() {
return STANDARD_MODE;
}
public void setSTANDARD_MODE(String STANDARD_MODE) {
this.STANDARD_MODE = STANDARD_MODE;
}
public LightModes() {
this.NIGHT_MODE = "NIGHT";
this.STANDARD_MODE = "STANDARD";
this.SOFT_MODE = "SOFT";
}
}
class SmartDevice {
private String name;
private double location;
private boolean switchedOn;
public SmartDevice(String name, double location, boolean switchedOn) {
this.name = name;
this.location = location;
this.switchedOn = switchedOn;
}
public String getName() {
return name;
}
public double getLocation() {
return location;
}
public boolean isSwitchedOn() {
return switchedOn;
}
}
class SmartLamp extends SmartDevice {
private LightModes lightModes;
public LightModes getLightModes() {
return lightModes;
}
public void setLightModes(LightModes lightModes) {
this.lightModes = lightModes;
}
public SmartLamp(String name, double location, boolean switchedOn) {
super(name, location, switchedOn);
}
public SmartLamp(LightModes lightModes, String name, double location, boolean switchedOn) {
super(name, location, switchedOn);
this.lightModes = lightModes;
}
#Override
public String toString() {
return "SmartLamp{" + "\nName." + getName() + "\nLocation." + getLocation()
+ "\nSwitchedOn." + isSwitchedOn() + "\nMode=" + getLightModes() + '}';
}
}
Henlo,
Basically what im trying to do is get user inputs and store in a custom object but I have no idea on how to go about it. I have created a loadDataFromConfig() method? that works fine when creating the object SmartHome app = new SmartHome(loadDataFromConfig());.
But I am completely stumped on how to get user inputs and store them in this format: dev[0] = new SmartDevice("device 1",1.3,true);.
All the code that is meant to run should be inside the main method in Step1.java
Here are the 3 classes used for the code (ignore comments they are just notes for me):
package SmartHomeApp;
public class SmartDevice {
private String name;
private double location;
private boolean switchedOn;
public SmartDevice(String val1, double val2, boolean val3) {
setName(val1);
setLocation(val2);
setSwitchedOn(val3);
}
//YOU CANT ACCESS the 'private classes' so you need to GET them
public void setName(String value) {name = value;}
public void setLocation(double value) {location = value;}
public void setSwitchedOn(boolean value) {switchedOn = value;}
public String getName() {return name;}
public double getLocation() {return location;}
public boolean getSwitchedOn() {return switchedOn;}
}
package SmartHomeApp;
public class SmartHome
{
private SmartDevice[] smrtDev;
public SmartHome(int size) {
smrtDev = new SmartDevice[size];
}
public SmartHome(SmartDevice[] values) {
smrtDev = values;
}
public int size() {return smrtDev.length;}
// can't do toString() for some reason??
public void ToString() {
for(int i=0; i<size();i++)
{
if(smrtDev[i] != null ){
System.out.println("----------");
System.out.println("-DEVICE "+(i+1)+"-");
System.out.println("----------");
System.out.println("Name: "+smrtDev[i].getName());
System.out.println("Location: "+smrtDev[i].getLocation());
System.out.println("Switched On: "+smrtDev[i].getSwitchedOn());
}
}
}
}
package SmartHomeApp;
import java.util.*;
public class Step1 {
public static void main(String args[]) {
SmartHome app = new SmartHome(loadDataFromConfig());
app.ToString();
}
public static SmartDevice[] loadDataFromConfig()
{
SmartDevice[] dev = new SmartDevice[20];
dev[0] = new SmartDevice("device 1",1.3,true);
dev[1] = new SmartDevice("device 2",2.3,false);
dev[2] = new SmartDevice("device 3",3.3,true);
dev[4] = new SmartDevice("device 5",4.3,false);
dev[19] = new SmartDevice("device 20",5.3,false);
return dev;
}
}
Some of the improvements required in your code are as follows:
Follow Java naming conventions e.g. ToString() should be toString(). Check this to learn more about toString(). Most of the IDEs (e.g. eclipse) provide a feature to generate toString() method on click of a button. Whatever way (either manual or with the help of your IDE) you generate it, it must return a String.
You should do away with using next(), nextInt(), nextDouble() etc. and use nextLine() instead. Check this to learn more it. To give you an idea what problems next(), nextDouble() can cause, try entering a name with a space e.g.
Enter size:
2
Name:
Light Amplification by Stimulated Emission of Radiation
Location:
Exception in thread "main" java.util.InputMismatchException
at java.base/java.util.Scanner.throwFor(Scanner.java:939)
at java.base/java.util.Scanner.next(Scanner.java:1594)
at java.base/java.util.Scanner.nextDouble(Scanner.java:2564)
at Main.main(Main.java:83)
Given below is a sample code incorporating the improvements mentioned above:
import java.util.Scanner;
class SmartDevice {
private String name;
private double location;
private boolean switchedOn;
public SmartDevice(String val1, double val2, boolean val3) {
setName(val1);
setLocation(val2);
setSwitchedOn(val3);
}
// YOU CANT ACCESS the 'private classes' so you need to GET them
public void setName(String value) {
name = value;
}
public void setLocation(double value) {
location = value;
}
public void setSwitchedOn(boolean value) {
switchedOn = value;
}
public String getName() {
return name;
}
public double getLocation() {
return location;
}
public boolean getSwitchedOn() {
return switchedOn;
}
#Override
public String toString() {
return "SmartDevice [name=" + name + ", location=" + location + ", switchedOn=" + switchedOn + "]";
}
}
class SmartHome {
private SmartDevice[] smrtDev;
public SmartHome(int size) {
smrtDev = new SmartDevice[size];
}
public SmartHome(SmartDevice[] values) {
smrtDev = values;
}
public int size() {
return smrtDev.length;
}
#Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (SmartDevice smartDevice : smrtDev) {
sb.append(smartDevice.toString()).append("\n");
}
return sb.toString();
}
}
public class Main {
public static void main(String[] args) {
Scanner myObj = new Scanner(System.in);
int size = getPositiveInt(myObj, "Enter size: ");
SmartDevice[] newList = new SmartDevice[size];
for (int i = 0; i < newList.length; i++) {
System.out.print("Name: ");
String x = myObj.nextLine();
double y = getFloatingPointNumber(myObj, "Location: ");
boolean z = getBoolean(myObj, "Is on?: ");
newList[i] = new SmartDevice(x, y, z);
}
SmartHome newDevice = new SmartHome(newList);
System.out.println(newDevice);
}
static int getPositiveInt(Scanner in, String message) {
boolean valid;
int n = 0;
do {
valid = true;
System.out.print(message);
try {
n = Integer.parseInt(in.nextLine());
if (n <= 0) {
throw new IllegalArgumentException();
}
} catch (IllegalArgumentException e) {
System.out.println("This in not a positive integer. Please try again.");
valid = false;
}
} while (!valid);
return n;
}
static double getFloatingPointNumber(Scanner in, String message) {
boolean valid;
double n = 0;
do {
valid = true;
System.out.print(message);
try {
n = Double.parseDouble(in.nextLine());
} catch (NumberFormatException | NullPointerException e) {
System.out.println("This in not a number. Please try again.");
valid = false;
}
} while (!valid);
return n;
}
static boolean getBoolean(Scanner in, String message) {
System.out.print(message);
return Boolean.parseBoolean(in.nextLine());
}
}
A sample run:
Enter size: x
This in not a positive integer. Please try again.
Enter size: -2
This in not a positive integer. Please try again.
Enter size: 10.5
This in not a positive integer. Please try again.
Enter size: 2
Name: Light Amplification by Stimulated Emission of Radiation
Location: 123.456
Is on?: true
Name: Vacuum Diode
Location: 234.567
Is on?: no
SmartDevice [name=Light Amplification by Stimulated Emission of Radiation, location=123.456, switchedOn=true]
SmartDevice [name=Vacuum Diode, location=234.567, switchedOn=false]
So as suggested I tried to do the following:
public static void main(String args[]) {
Scanner myObj = new Scanner(System.in);
System.out.println("Enter size: ");
int size = myObj.nextInt();
SmartDevice[] newList = new SmartDevice[size];
for(int i =0; i<newList.length;i++) {
System.out.println("Name: ");
String x = myObj.next();
System.out.println("Location: ");
double y = myObj.nextDouble();
System.out.println("Is on?: ");
boolean z = myObj.nextBoolean();
newList[i] = new SmartDevice(x,y,z);
}
SmartHome newDevice = new SmartHome(newList);
newDevice.ToString();
}
Got it working but not sure if this is the most efficient way to do so??
Im trying to create a small character builder, using inheritance. i have CreateCharacter CharacterRace then a Dwarf class. i made a variable with type CharacterRace in CreateCharacter and a variable with type Dwarf in CharacterRace. i have an object of CreateCharacter in my main method demo and its not letting me call the methods from the Dwarf class, to make a dwarf character. im thinking ineed to pass a dwarf object in characterRace? im just not sure how. heres my code: (its a bit long my apologies)
package characterCreation;
public class CreateCharacter {
private CharacterClass characterClass;
private CharacterRace characterRace;
private Name name;
public CreateCharacter(String characterName,CharacterClass characterClass,CharacterRace characterRace) {
this.name = new Name(characterName);
this.characterClass = characterClass;
this.characterRace = characterRace;
}
public CreateCharacter(){
}
public CharacterClass getCharacterClass() {
return characterClass;
}
public void setCharacterClass(CharacterClass characterClass) {
this.characterClass = characterClass;
}
public CharacterRace getCharacterRace() {
return characterRace;
}
public void setCharacterRace(CharacterRace characterRace) {
this.characterRace = characterRace;
}
public Name getName(){
return name;
}
public void setName(Name name){
this.name = name;
}
#Override
public String toString() {
return "CreateCharacter [name=" + name + ", characterRace=" + characterRace + ", characterClass="
+ characterClass + "]";
}
}
package characterCreation;
public class CharacterRace {
protected String raceName;
protected double mana;
protected double hp;
private Dwarf dwarf;
public CharacterRace(String raceName,double mana, double hp) {
this.raceName = raceName;
this.mana = mana;
this.hp = hp;
}
public CharacterRace(){
}
public String getRaceName() {
return raceName;
}
public Dwarf getDwarf() {
return dwarf;
}
public void setDwarf(Dwarf dwarf) {
this.dwarf = dwarf;
}
public double getMana() {
return mana;
}
public double getHp() {
return hp;
}
#Override
public String toString() {
return "CharacterRace [dwarf=" + dwarf + "]";
}
}
package characterCreation;
public class Dwarf extends CharacterRace {
public Dwarf(String raceName,double mana, double hp) {
super(raceName,mana,hp);
}
public double getMana() {
mana = 5;
return mana;
}
public double getHp() {
hp = 10;
return hp;
}
public String getRaceName(){
return raceName = "Dwarf";
}
#Override
public String toString() {
return "Dwarf [mana=" + mana + ", hp=" + hp + ", getRaceName()=" + getRaceName() + "]";
}
}
package characterCreation;
import java.util.Scanner;
public class CharacterDemo {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
CreateCharacter create = new CreateCharacter();
System.out.println("Choose your Race: ");
String userRace = input.next();
create.setName(new Name("Daxel"));
//create.setCharacterRace(race);
System.out.println(create.getName());
//Dwarf dwarf = new Dwarf();
System.out.println(create.getCharacterRace().getDwarf().getRaceName());
//System.out.println(create.getCharacterRace().setDwarf(new Dwarf("dwarf",10,5)));
}
}
You have to call setCharacterRace() on create; then call setDwarf() on the characterRace; otherwise create.getCharacterRace() would be null and create.getCharacterRace().getDwarf() would throw NullPointerException.
I don't understand the logic behind your code, but try the code below:
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
CreateCharacter create = new CreateCharacter();
System.out.println("Choose your Race: ");
String userRace = input.next();
create.setName(new Name("Daxel"));
//***********new code starts******
CharacterRace myRace = new CharacterRace(userRace, 20, 9);
myRace.setDwarf(new Dwarf("dwarf",10,5));
create.setCharacterRace(myRace);
//***********new code ends********
//create.setCharacterRace(race);
System.out.println(create.getName());
//Dwarf dwarf = new Dwarf();
System.out.println(create.getCharacterRace().getDwarf().getRaceName());
//System.out.println(create.getCharacterRace().setDwarf(new Dwarf("dwarf",10,5)));
}
I need help removing a specific object from an arraylist. I'm creating objects with a unique ID and grade for each object.I'm trying to use this unique ID to remove an object from the arraylist, but am having trouble figuring out why my code isn't working. I have my main Driver class, a superclass, and a subclass.
The subclass is where the object information is passed from and extends the superclass. I thought that since the subclass is extended, it would be able to be defined from there.
The problem that is occurring is line 49 of the superclasss. Eclipse says that getStudentID isn't defined in the class.
I am trying to modify code that my instructor provided in order to locate this unique ID that an object in the arraylist has. I believe I did everything correctly, but the method "locationPerson" doesn't seem to see the getStudentID() method in the subclass.
Here is the code. Any help would be appreciated!
Subclass
public class StudentEnrollee extends ClassSection{
private int grade;
private String studentID;
StudentEnrollee() {
setStudentID("000-000");
setGrade(0);
}
StudentEnrollee(String ID, int theGrade) {
setStudentID(ID);
setGrade(0);
}
//STUDENT ID
public String getStudentID() {
return studentID;
}
public void setStudentID(String theStudentID) {
this.studentID = theStudentID;
}
//STUDENT GRADE
public int getGrade() {
return grade;
}
public void setGrade(int studentGrade) {
this.grade = studentGrade;
}
public String toString() {
return("Student ID : " + studentID + "\n" +
"Student Grade: " + grade);
}
}
Superclass
import java.util.ArrayList;
import java.util.List;
public class ClassSection {
private int crn, courseNumber, capacity, enrollment, ID, student;
private String departmentCode, courseMode, meetingDay, meetingTime;
//CONSTRUCTOR
ClassSection() {
setCrn(0);
setDepartmentCode("");
setCourseNumber(0);
setCourseMode("");
setMeetingDay("");
setMeetingTime("");
setCapacity(0);
setEnrollment(0);
setID(0);
}
ClassSection(int crn, String departmentCode, int courseNumber, String courseMode, String meetingDay, String meetingTime, int capacity, int enrollment, int ID) {
setCrn(crn);
setDepartmentCode(departmentCode);
setCourseNumber(courseNumber);
setCourseMode(courseMode);
setMeetingDay(meetingDay);
setMeetingTime(meetingTime);
setCapacity(capacity);
setEnrollment(enrollment);
setID(ID);
}
//STUDENT ENROLL ARRAY
List < StudentEnrollee > studentList = new ArrayList < StudentEnrollee > ();
public int getStudent() {
return student;
}
public void addStudent(StudentEnrollee studentObject) {
studentList.add(studentObject);
}
//LOCATING PERSON
public ClassSection locatePerson(String getStudentID) {
for (ClassSection personObject: studentList) {
if (personObject.getStudentID().equals(getStudentID)) {
return personObject;
}
}
return null;
}
//Delete person
public void deletePerson(String studentID) {
ClassSection personObject = locatePerson(studentID); // we'll use our locatePerson method find the index of a Person with a given socSecNum.
if (personObject != null) studentList.remove(personObject); // if element i contains the target SSN, remove it.
}
//DISPLAY LIST OF ENROLLEE
public void displayListV1() {
for (int i = 0; i < studentList.size(); i++) // the old way
{
System.out.println(studentList.get(i) + "\n");
}
}
//CRN
public int getCrn() {
return crn;
}
void setCrn(int classCrn) {
this.crn = classCrn;
}
//DEPARTMENT CODE
public String getDepartmentCode() {
return departmentCode;
}
void setDepartmentCode(String classDepartmentCode) {
this.departmentCode = classDepartmentCode;
}
//COURSE NUMBER
public int getCourseNumber() {
return courseNumber;
}
void setCourseNumber(int classCourseNumber) {
this.courseNumber = classCourseNumber;
}
//COURSE LOCATION
public String getCourseMode() {
return courseMode;
}
public void setCourseMode(String classCourseMode) {
this.courseMode = classCourseMode;
}
//MEETING DAY
public String getMeetingDay() {
return meetingDay;
}
public void setMeetingDay(String classMeetingDay) {
this.meetingDay = classMeetingDay;
}
//MEETING TIMES
public String getMeetingTime() {
return meetingTime;
}
public void setMeetingTime(String classMeetingTime) {
this.meetingTime = classMeetingTime;
}
//CAPACITY
public int getCapacity() {
return capacity;
}
public void setCapacity(int classCapacity) {
this.capacity = classCapacity;
}
//ENROLLMENT
public int getEnrollment() {
return enrollment;
}
public void setEnrollment(int classEnrollment) {
this.enrollment = classEnrollment;
}
//INSTRUCTOR ID
public int getID() {
return ID;
}
public void setID(int instructorID) {
this.ID = instructorID;
}
//TO STRING METHOD
public String toString() {
return ("CRN :" + crn + "\n" +
"Department :" + departmentCode + "\n" +
"Course Number :" + courseNumber + "\n" +
"Instructional mode :" + courseMode + "\n" +
"Meeting days :" + meetingDay + "\n" +
"Meeting times :" + meetingTime + "\n" +
"Capacity :" + capacity + "\n" +
"Enrollment :" + enrollment + "\n" +
"Instructor’s ID :" + ID + "\n");
}
}
Driver
public class ClassDriver {
public static void main(String[] args) {
ClassSection firstInstance = new ClassSection(20008, "CHM", 000, "Online", "N/A", "N/A", 30, 21, 231);
ClassSection secondInstance = new ClassSection();
ClassSection addToList = new ClassSection();
StudentEnrollee studentObj1 = new StudentEnrollee();
StudentEnrollee studentObj2 = new StudentEnrollee();
StudentEnrollee studentObj3 = new StudentEnrollee();
studentObj1.setGrade(5);
studentObj1.setID(230);
studentObj2.setGrade(76);
studentObj2.setID(45);
studentObj3.setGrade(2);
studentObj3.setID(34);
addToList.addStudent(studentObj1);
addToList.addStudent(studentObj2);
addToList.addStudent(studentObj3);
addToList.deletePerson("45");
addToList.displayListV1();
System.out.println(firstInstance.toString());
System.out.println(secondInstance.toString());
}
}
I think it should be:
public StudentEnrollee locatePerson(String getStudentID) {
for (StudentEnrollee personObject: studentList) {
if (personObject.getStudentID().equals(getStudentID)) {
return personObject;
}
}
return null;
}
You are trying to use a method from subclass in superclass, so you got the error that this method is not defined. You can use all method of superclass in subclasses, but it doesn't work another way.
The getStudentID() method is declared in class StudentEnrollee. In the code below, personObject, which is defined as a ClassSection object, does not have access to it.
public ClassSection locatePerson(String getStudentID) {
for (ClassSection personObject: studentList) {
if (personObject.getStudentID().equals(getStudentID)) {
return personObject;
}
}
return null;
}
The solution can vary based on your program logic, but the straightforward way is to replace ClassSection with StudentEnrollee:
public StudentEnrollee locatePerson(String getStudentID) {
for (StudentEnrollee personObject: studentList) {
if (personObject.getStudentID().equals(getStudentID)) {
return personObject;
}
}
return null;
}
I'm trying to access the method changeAll from class MarkMaker the following way:
import java.util.Scanner;
class Question10e
{
public static void main(String[] args)
{
System.out.println();
Scanner input = new Scanner(System.in);
System.out.print("Enter mark 1: ");
int newm1=input.nextInt();
System.out.print("Enter mark 2: ");
int newm2=input.nextInt();
System.out.print("Enter mark 3: ");
int newm3=input.nextInt();
String linem=input.nextLine();
System.out.print("Enter a master password: ");
String masterpass = input.next();
linem=input.nextLine();
MarkMaker mm = new MarkMaker(masterpass);
Mark masterMark1 = mm.makeMark(newm1);
Mark masterMark2 = mm.makeMark(newm2);
Mark masterMark3 = mm.makeMark(newm3);
try{
System.out.println("The new mark 1 is "+masterMark1.provisional(masterpass));
System.out.println("The new mark 2 is "+masterMark2.provisional(masterpass));
System.out.println("The new mark 3 is "+masterMark3.provisional(masterpass));
System.out.println("The new master password is is "+masterMark1.returnPass());
int avg = mm.average();
System.out.println("The average is "+avg);
changeAll(5.5, 3);
}
catch(IncorrectPasswordException e){}
}
}
This is the MarkMaker class:
import java.util.*;
class MarkMaker{
private String masterPass = "";
private ArrayList<Mark> masterArr = new ArrayList<Mark>();
public MarkMaker(String masterPass)
{
this.masterPass = masterPass;
}
public Mark makeMark(int m)
{
Mark newMarkObj = new Mark(m,masterPass);
masterArr.add(newMarkObj);
return newMarkObj;
}
public ArrayList<Mark> returnMasterArr()
{
return masterArr;
}
public int average() throws IncorrectPasswordException
{
int n = 0;
for(int i=0; i<masterArr.size(); i++)
{
n = n + masterArr.get(i).provisional(masterPass);
}
int avg = n/masterArr.size();
return avg;
}
public void changeAll(double d, int x) throws IncorrectPasswordException
{
for(int i=0; i<masterArr.size(); i++)
{
double currentMark = masterArr.get(i).provisional(masterPass);
System.out.println("Current mark is: "+currentMark);
currentMark = currentMark*d;
System.out.println("Current mark is: "+currentMark);
currentMark = Math.ceil(currentMark);
System.out.println("Current mark is: "+currentMark);
}
} }
And this is the Mark class:
class Mark
{
private int value;
private String password;
boolean released;
public Mark(int value, String password)
{
this.value = value;
this.password = password;
released = false;
}
public void release(String p) throws IncorrectPasswordException
{
if(p.equals(password))
{
if(released==false)
released = true;
}
else throw new IncorrectPasswordException(p);
}
public int value() throws UnReleasedException
{
if(released==true)
return value;
else
throw new UnReleasedException();
}
public int provisional(String p) throws IncorrectPasswordException
{
if(p.equals(password))
return value;
else
throw new IncorrectPasswordException(p);
}
public void change(String p, int arg) throws IncorrectPasswordException
{
if(p.equals(password))
value = arg;
else
throw new IncorrectPasswordException(p);
}
public String returnPass()
{
return password;
}
public boolean isReleased()
{
return released;
}
public boolean equals(Mark m2) throws UnReleasedException
{
if(this.isReleased() && m2.isReleased())
{ //it throws an error, that's why i'm using the Unreleased Exception
if(this.value()==m2.value())
return true;
}
throw new UnReleasedException();
} }
The problem is that I always get a "cannot find symbol error - method changeAll(double, int), location class Question10e"
Question10e doesn't have this method. Perhaps you intended to call this on an instance of a class which does like.
mm.changeAll(5.5, 3);
changeAll is a method which belongs to the MarkMaker class rather than the current Question10e class where you are attempting to call the method:
mm.changeAll(5.5, 3);
You need to call changeAll() through a MarkMarker object. It doesn't exist in your Question10e class. So, you could do this by:
mm.changeAll(5.5, 3)
Just because changeAll() is public doesn't mean that you can call it from anywhere. It simply means that a MarkMarker object can call it from anywhere.
You need
mm.changeAll(5.5, 3);