Develop Reference

sorting an array of objects by some property without using collections that is doing manually

**In this i am trying to sort an array of objects by their id's whose age > 30 but compiler is giving error in searchVoteByAge function in while loop :
while((j>-1)&& (v[j].getVoterId() > key.getVoterId())) in this line **
error :Exception in thread "main"
java.lang.NullPointerException at algorithms.Dijstra_algo.searchVoterByAge(Dijstra_algo.java:77) at
algorithms.Dijstra_algo.main(Dijstra_algo.java:55)
import java.util.Scanner;
public class Demo
{
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
Voter voter[]=new Voter[4];
for(int i=0;i<voter.length;i++){
int v_id=sc.nextInt();
sc.nextLine();
String v_nme=sc.next();
sc.nextLine();
int v_age=sc.nextInt();
sc.nextLine();
boolean is_vote_casted=sc.nextBoolean();
sc.nextLine();
String constituency=sc.next();
sc.nextLine();
voter[i]=new Voter();
voter[i].setVoterId(v_id);
voter[i].setVoterName(v_nme);
voter[i].setVoterAge(v_age);
voter[i].setVoteCasted(is_vote_casted);
voter[i].setConstituency(constituency);
}
String cons=sc.next();
int c=findTotal(voter,cons);
if(c>0)
System.out.println(c);
else
System.out.println("No votes Casted");
Voter v[]=searchVoterByAge(voter);
if(v.length > 0){
for(Voter obj: v){
System.out.println(obj.getVoterId());
}
}
else
System.out.println("No such voters");
}
private static Voter[] searchVoterByAge(Voter[] voters) {
Voter v[]=new Voter[voters.length];
int k=0,f=0;
for(Voter obj:voters) {
if(obj.getVoterAge()<30) {
v[k]=new Voter();
v[k++]=obj;
f=1;
}
}
for(int i=1;i<v.length;i++) {
Voter key=v[i];
int j=i-1;
while((j>-1)&& (v[j].getVoterId() > key.getVoterId())) {
v[j+1]=v[j];
j--;
}
v[j+1]=key;
}
if(f == 0) {
return new Voter[0];
}
else
return v;
}
static int findTotal(Voter voters[],String s){
int c=0;
for(Voter voter:voters){
if(voter.isVoteCasted() && voter.getConstituency().equals(s)){
c++;
}
}
return c;
}
}
** Voter Class**
public class Voter {
private int voterId;
private String voterName;
private int voterAge;
private String constituency;
private boolean isVoteCasted;
public int getVoterId() {
return voterId;
}
public void setVoterId(int voterId) {
this.voterId = voterId;
}
public String getVoterName() {
return voterName;
}
public void setVoterName(String voterName) {
this.voterName = voterName;
}
public int getVoterAge() {
return voterAge;
}
public void setVoterAge(int voterAge) {
this.voterAge = voterAge;
}
public String getConstituency() {
return constituency;
}
public void setConstituency(String constituency) {
this.constituency = constituency;
}
public boolean isVoteCasted() {
return isVoteCasted;
}
public void setVoteCasted(boolean isVoteCasted) {
this.isVoteCasted = isVoteCasted;
}
}

How to get user input and store in custom object? JAVA

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??

Java error - invalid method declaration; return type required

I'm trying to complete this java program, but every time I try to compile it I get this error. Can someone figure out why my program is doing this. It seems that no matter what I do I still happen to get an error on my program. I tried everything I know to see if it would work. Please someone help me.
import java.util.Scanner;
public class Period
{
private static String phrase;
public static void main(String [] args)
{
Scanner keyboard = new Scanner(System.in);
String userInput;
int[] letter = new int [27];
int number = keyboard.nextInt();
System.out.println("Enter a sentence with a period at the end.");
userInput = keyboard.nextLine();
userInput.toLowerCase();
}
// this is where the error is occuring at.
public Sorter(String newPhrase)
{
phrase=newPhrase.substring(0,newPhrase.indexOf("."));
}
private int charToInt(char currentLetter)
{
int converted=(int)currentLetter-(int)'a';
return converted;
}
private void writeToArray()
{
char next;
for (int i=0;i<phrase.length();i++)
{
next=(char)phrase.charAt(i);
sort(next);
}
}
private String cutPhrase()
{
phrase=phrase.substring(0,phrase.indexOf("."));
return phrase;
}
private void sort(char toArray)
{
int placement=charToInt(toArray);
if (placement<0)
{
alphabet[26]=1;
}
else
{
alphabet[placement]=alphabet[placement]+1;
}
}
public void entryPoint()
{
writeToArray();
displaySorted();
}
private void displaySorted()
{
for (int q=0; q<26;q++)
{
System.out.println("Number of " + (char)('a'+q) +"'s: "+alphabet[q]);
}
}
}

The 'Sorter' method is missing a return type. It should be:
public void Sorter(String newPhrase)
{
phrase = newPhrase.substring(0, newPhrase.indexOf("."));
}
The method is not called anywhere, so i am not sure if this is what you intended it to do.

add the void return type:
public void Sorter(String newPhrase) // HERE
{
phrase=newPhrase.substring(0,newPhrase.indexOf("."));
}

There are a lot of errors in the above code - see below for some code that runs, though i can't be sure it does exactly what you want given the limited scope of the question.
I don't want to stray too far from the original question, but you should really consider using instance variables and encapsulating your data, rather than relying on static variables.
import java.util.Scanner;
public class Period
{
private static String phrase;
private static int[] alphabet = new int [27];
public static void main(String [] args)
{
System.out.println("Enter a sentence with a period at the end.");
Scanner keyboard = new Scanner(System.in);
phrase = keyboard.nextLine().toLowerCase();
Period period = new Period();
period.entryPoint();
}
public void Sorter(String newPhrase)
{
phrase = newPhrase.substring(0,newPhrase.indexOf("."));
}
private int charToInt(char currentLetter)
{
int converted=(int)currentLetter-(int)'a';
return converted;
}
private void writeToArray()
{
char next;
for (int i=0;i<phrase.length();i++)
{
next=(char)phrase.charAt(i);
sort(next);
}
}
private String cutPhrase()
{
phrase=phrase.substring(0,phrase.indexOf("."));
return phrase;
}
private void sort(char toArray)
{
int placement=charToInt(toArray);
if (placement<0)
{
alphabet[26]=1;
}
else
{
alphabet[placement]=alphabet[placement]+1;
}
}
public void entryPoint()
{
writeToArray();
displaySorted();
}
private void displaySorted()
{
for (int q=0; q<26;q++)
{
System.out.println("Number of " + (char)('a'+q) +"'s: "+alphabet[q]);
}
}
}

Confusion on using instanceof along with other inherited data

I have already made a posting about this program once, but I am once again stuck on a new concept that I am learning (Also as a side note; I am a CS student so please DO NOT simply hand me a solution, for my University has strict code copying rules, thank you.). There are a couple of difficulties I am having with this concept, the main one being that I am having a hard time implementing it to my purposes, despite the textbook examples making perfect sense. So just a quick explanation of what I'm doing:
I have an entity class that takes a Scanner from a driver. My other class then hands off the scanner to a superclass and its two subclasses then inherit that scanner. Each class has different data from the .txt the Scanner read through. Then those three classes send off their data to the entity to do final calculations. And that is where my problem lies, after all the data has been read. I have a method that displays a new output along with a few methods that add data from the super along with its derived classes.EDIT: I simply cannot figure out how to call the instance variable of my subclasses through the super so I can add and calculate the data.
Here are my four classes in the order; Driver, Entity, Super, Subs:
public static final String INPUT_FILE = "baseballTeam.txt";
public static void main(String[] args) {
BaseballTeam team = new BaseballTeam();
Scanner inFile = null;
try {
inFile = new Scanner(new File(INPUT_FILE));
team.loadTeam(inFile);
team.outputTeam();
} catch (FileNotFoundException e) {
System.out.println("File " + INPUT_FILE + " Not Found.");
System.exit(1);
}
}
}
public class BaseballTeam {
private String name;
private Player[] roster = new Player[25];
Player pitcher = new Pitcher();
Player batter = new Batter();
BaseballTeam() {
name = "";
}
public String getName() {
return name;
}
public void setName(String aName) {
name = aName;
}
public void loadTeam(Scanner input) {
name = input.nextLine();
for (int i = 0; i < roster.length; i++) {
if (i <= 9) {
roster[i] = new Pitcher();
}
else if ((i > 9) && (i <= 19)) {
roster[i] = new Batter();
}
else if (i > 19) {
roster[i] = new Player();
}
roster[i].loadData(input);
roster[i].generateDisplayString();
//System.out.println(roster[i].generateDisplayString()); //used sout to test for correct data
}
}
public void outputTeam() {
if ((pitcher instanceof Player) && (batter instanceof Player)) {
for (int i = 0; i < roster.length; i++) {
System.out.println(roster[i].generateDisplayString());
}
}
//How do I go about doing calculates?
public int calculateTeamWins() {
if ((pitcher instanceof ) && (batter instanceof Batter)) {
}
return 0;
}
public int calculateTeamSaves() {
if ((pitcher instanceof Pitcher) && (batter instanceof Batter)) {
}
return 0;
}
public double calculateTeamERA() {
if ((pitcher instanceof Pitcher) && (batter instanceof Batter)) {
}
return 0;
}
public double calculateTeamWHIP() {
if ((pitcher instanceof Pitcher) && (batter instanceof Batter)) {
}
return 0;
}
public double calculateTeamBattingAverage() {
if ((pitcher instanceof Pitcher) && (batter instanceof Batter)) {
}
return 0;
}
public int calculateTeamHomeRuns() {
if ((pitcher instanceof Pitcher) && (batter instanceof Batter)) {
}
return 0;
}
public int calculateTeamRBI() {
if ((pitcher instanceof Pitcher) && (batter instanceof Batter)) {
}
return 0;
}
public int calculateStolenBases() {
if ((pitcher instanceof Pitcher) && (batter instanceof Batter)) {
}
return 0;
}
}
public class Player {
protected String name;
protected String position;
Player(){
name = "";
position = "";
}
public String getName() {
return name;
}
public void setName(String aName) {
name = aName;
}
public String getPosition() {
return position;
}
public void setPosition(String aPosition) {
position = aPosition;
}
public void loadData(Scanner input){
do {
name = input.nextLine();
} while (name.equals(""));
position = input.next();
//System.out.println(generateDisplayString());
}
public String generateDisplayString(){
return "Name: " + name + ", Position:" + position;
}
}
public class Pitcher extends Player {
private int wins;
private int saves;
private int inningsPitched;
private int earnedRuns;
private int hits;
private int walks;
private double ERA;
private double WHIP;
Pitcher() {
super();
wins = 0;
saves = 0;
inningsPitched = 0;
earnedRuns = 0;
hits = 0;
walks = 0;
}
public int getWins() {
return wins;
}
public void setWins(int aWins) {
wins = aWins;
}
public int getSaves() {
return saves;
}
public void setSaves(int aSaves) {
saves = aSaves;
}
public int getInningsPitched() {
return inningsPitched;
}
public void setInningsPitched(int aInningsPitched) {
inningsPitched = aInningsPitched;
}
public int getEarnedRuns() {
return earnedRuns;
}
public void setEarnedRuns(int aEarnedRuns) {
earnedRuns = aEarnedRuns;
}
public int getHits() {
return hits;
}
public void setHits(int aHits) {
hits = aHits;
}
public int getWalks() {
return walks;
}
public void setWalks(int aWalks) {
walks = aWalks;
}
#Override
public void loadData(Scanner input) {
super.loadData(input);
wins = input.nextInt();
saves = input.nextInt();
inningsPitched = input.nextInt();
earnedRuns = input.nextInt();
hits = input.nextInt();
walks = input.nextInt();
}
#Override
public String generateDisplayString() {
calculateERA();
calculateWHIP();
return String.format(super.generateDisplayString() + ", Wins:%1d, Saves:%1d,"
+ " ERA:%1.2f, WHIP:%1.3f ", wins, saves, ERA, WHIP);
}
public double calculateERA() {
try {
ERA = ((double)(earnedRuns * 9) / inningsPitched);
} catch (ArithmeticException e) {
ERA = 0;
}
return ERA;
}
public double calculateWHIP() {
try {
WHIP = ((double)(walks + hits) / inningsPitched);
} catch (ArithmeticException e) {
WHIP = 0;
}
return WHIP;
}
}
public class Batter extends Player {
private int atBats;
private int hits;
private int homeRuns;
private int rbi;
private int stolenBases;
private double batAvg;
Batter() {
super();
atBats = 0;
hits = 0;
homeRuns = 0;
rbi = 0;
stolenBases = 0;
}
public int getAtBats() {
return atBats;
}
public void setAtBats(int aAtBats) {
atBats = aAtBats;
}
public int getHits() {
return hits;
}
public void setHits(int aHits) {
hits = aHits;
}
public int getHomeRuns() {
return homeRuns;
}
public void setHomeRuns(int aHomeRuns) {
homeRuns = aHomeRuns;
}
public int getRbi() {
return rbi;
}
public void setRbi(int aRbi) {
rbi = aRbi;
}
public int getStolenBases() {
return stolenBases;
}
public void setStolenBases(int aStolenBases) {
stolenBases = aStolenBases;
}
#Override
public void loadData(Scanner input) {
super.loadData(input);
atBats = input.nextInt();
hits = input.nextInt();
homeRuns = input.nextInt();
rbi = input.nextInt();
stolenBases = input.nextInt();
}
#Override
public String generateDisplayString() {
calculateBattingAverage();
return String.format(super.generateDisplayString() +
", Batting Average:%1.3f, Home Runs:%1d, RBI:%1d, Stolen Bases:%1d"
, batAvg, homeRuns, rbi, stolenBases);
}
public double calculateBattingAverage() {
try{
batAvg = ((double)hits/atBats);
} catch (ArithmeticException e){
batAvg = 0;
}
return batAvg;
}
}
Also, its probably easy to tell I'm still fairly new here, because I just ran all my classes together in with the code sample and I can't figure out to add the gaps, so feel free to edit if need be.

The typical usage of instanceof in the type of scenario you're describing would be
if (foo instanceof FooSubclass) {
FooSubclass fooSub = (FooSubclass) foo;
//foo and fooSub now are references to the same object, and you can use fooSub to call methods on the subclass
} else if (foo instanceof OtherSubclass) {
OtherSubclass otherSub = (OtherSubclass) foo;
//you can now use otherSub to call subclass-specific methods on foo
}
This is called "casting" or "explicitly casting" foo to FooSubclass.

the concept to call the methods of your subclasses is called polymorphism.
In your runtime the most specific available method is called provided that the method names are the same.
so you can
Superclass class = new Subclass();
class.method();
and the method provided that overwrites the method in Superclass will be called, even if it's defined in the Subclass.
Sorry for my english, I hope that helps a little bit ;-)

Java cannot find symbol error - a method from another class

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);