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Using variables form other classes in java

I am trying to use two int variables from other classes in another class and then add them together into another variable and print the result. When I try this though, I always get a result of zero like the values are not being brought over into the new class and I can't figure out what the problem is.
Here is some example code:
class1
public static int finished = (match2.totalpoints + match3.iq);
public static void main(String[] args) throws InterruptedException {
// TODO Auto-generated method stub
Scanner s = new Scanner(System.in);
System.out.println("THIS IS YOUR OWN EXCLUSIVE IQ TEST OR MEMORY QUIZ OR WHATEVER....");
System.out.println("");
System.out.println("When taking the quiztest you have only two seconds before making each guess");
match2 m = new match2();
System.out.println("THAT MEANS ACCORDING TO YOUR QUIZTEST YOU'VE GOT AN IQ OF " + finished + " POINTS");
}
}
EDIT: class2
public class match2 {
public static int totalpoints;
int a;
int b;
int c;
int d;
int e;
int f;
String guess;
String group;
String countdown[] = {
"3...",
"2...",
"1...",
""
};
String memorize[] = {
""
};
public match2() throws InterruptedException
{
int x = set2();
int y = set3();
int z = set4();
total(x, y, z);
System.out.println("For the next part of your IQ ASSesment\njust type back the words in CAPSLOCK in CAPSLOCK");
System.out.println("");
match3 n = new match3();
}
public void set1() throws InterruptedException
{
//Scanner s = new Scanner(System.in);
for (int i = 0; i < countdown.length; i++)
{
Thread.sleep(750);
System.out.println(countdown[i]);
}
}
public int set2() throws InterruptedException
{
Random r = new Random();
Scanner s = new Scanner(System.in);
System.out.println("press ENTER for your first set...");
s.nextLine();
set1();
int rv = 0;
a = r.nextInt(9) + 1;
b = r.nextInt(9) + 1;
c = r.nextInt(9) + 1;
d = r.nextInt(9) + 1;
group = "" + a + b + c + d;
System.out.println(group);
for (int i = 0; i < memorize.length; i++)
{
Thread.sleep(1500);
System.out.println(memorize[i]);
}
System.out.println("\n\n\n\n\n\n\n\n\n\n");
guess = "" + s.nextLine();
if(guess.equals(group))
{
System.out.println("nice +1 bruh");
rv = 1;
}
else if(!guess.equals(group))
{
System.out.println("almost");
}
return rv;
}
public int set3() throws InterruptedException
{
Random r = new Random();
Scanner s = new Scanner(System.in);
System.out.println("");
System.out.println("press ENTER for your next set...");
s.nextLine();
set1();
int rv = 0;
a = r.nextInt(9) + 1;
b = r.nextInt(9) + 1;
c = r.nextInt(9) + 1;
d = r.nextInt(9) + 1;
f = r.nextInt(9) + 1;
group = "" + a + b + c + d + f;
System.out.println(group);
for (int i = 0; i < memorize.length; i++)
{
Thread.sleep(1500);
System.out.println(memorize[i]);
}
System.out.println("\n\n\n\n\n\n\n\n\n\n");
guess = s.nextLine();
if(group.equals(guess))
{
rv = 1;
System.out.println("good");
}
else if(!guess.equals(group))
{
System.out.println("almost");
}
return rv;
}
public int set4() throws InterruptedException
{
Random r = new Random();
Scanner s = new Scanner(System.in);
System.out.println("");
System.out.println("press ENTER for your final set...");
s.nextLine();
set1();
int rv = 0;
a = r.nextInt(9) + 1;
b = r.nextInt(9) + 1;
c = r.nextInt(9) + 1;
d = r.nextInt(9) + 1;
e = r.nextInt(9) + 1;
f = r.nextInt(9) + 1;
group = "" + a + b + c + d + f + e;
System.out.println(group);
System.out.println("");
for (int i = 0; i < memorize.length; i++)
{
Thread.sleep(1500);
System.out.println(memorize[i]);
}
System.out.println("\n\n\n\n\n\n\n\n\n\n");
guess = "" + s.nextLine();
if(group.equals(guess))
{
rv = 1;
System.out.println("great");
}
else if(!group.equals(guess))
{
System.out.println("eeeh buzer sound");
}
return rv;
}
public int total(int x, int y, int z)
{
System.out.println("");
int totalpoints = (x + y + z);
if(totalpoints == 3)
{
System.out.println("YOU GOT THEM ALL");
}
if(totalpoints <= 2 && totalpoints >= 1)
{
System.out.println("YOU MISSED A TOTAL OF " + (3 - totalpoints));
}
if(totalpoints == 0)
{
System.out.println("HA! YOU MISSED THEM ALL");
}
return totalpoints;
}
}
EDIT: class3
public class match3 {
public static int iq;
String countupdown [] = {
"READY...",
"SET.....",
""
};
String memorize [] = {
""
};
public match3() throws InterruptedException
{
int mem1 = memory1();
int mem2 = memory2();
int mem3 = memory3();
totalMemory(mem1, mem2, mem3);
}
public void methodCountdown() throws InterruptedException
{
for(int i = 0; i < countupdown.length; i++)
{
Thread.sleep(1000);
System.out.println(countupdown[i]);
}
}
public int memory1() throws InterruptedException
{
int rv = 1;
Scanner s = new Scanner(System.in);
System.out.println("Press ENTER when ready");
s.nextLine();
methodCountdown();
String a = word1();
String b = word2();
System.out.println("The " + a + " ate the " + b);
String wordgroup = "" + a + " " + b;
for (int i = 0; i < memorize.length; i++)
{
Thread.sleep(1500);
System.out.println(memorize[i]);
}
System.out.println("\n\n\n\n\n\n\n\n\n\n");
String wordguess = "" + s.nextLine();
if(wordgroup.equals(wordguess))
{
System.out.println("awesome cock muncher a match");
rv = 1;
}
else if(!wordgroup.equals(wordguess))
{
System.out.println("nope");
}
return rv;
}
public int memory2() throws InterruptedException
{
int rv = 0;
Scanner s = new Scanner(System.in);
System.out.println("");
System.out.println("Press ENTER for your next set");
s.nextLine();
methodCountdown();
String a = word1();
String c = word3();
System.out.println("The " + a + " drove the " + c);
String wordgroup = "" + a + " " + c;
for (int i = 0; i < memorize.length; i++)
{
Thread.sleep(1500);
System.out.println(memorize[i]);
}
System.out.println("\n\n\n\n\n\n\n\n\n\n");
String wordguess = "" + s.nextLine();
if(wordgroup.equals(wordguess))
{
System.out.println("awesome cock muncher a match");
rv = 1;
}
else if(!wordgroup.equals(wordguess))
{
System.out.println("nope");
}
return rv;
}
public int memory3() throws InterruptedException
{
int rv = 0;
Scanner s = new Scanner(System.in);
System.out.println("");
System.out.println("Press ENTER for your next set");
s.nextLine();
methodCountdown();
String a = word1();
String d = word4();
System.out.println("The " + a + " visited the " + d);
String wordgroup = "" + a + " " + d;
for (int i = 0; i < memorize.length; i++)
{
Thread.sleep(1500);
System.out.println(memorize[i]);
}
System.out.println("\n\n\n\n\n\n\n\n\n\n");
String wordguess = "" + s.nextLine();
if(wordgroup.equals(wordguess))
{
System.out.println("awesome cock muncher a match");
rv = 1;
}
else if(!wordgroup.equals(wordguess))
{
System.out.println("nope");
}
return rv;
}
public static String word1()
{
String word = "";
Random r = new Random();
int cv = r.nextInt(3) + 1;
if(cv == 1)
{
word = "DOG";
}
else if(cv == 2)
{
word = "CAT";
}
else if(cv == 3)
{
word = "BIRD";
}
return word;
}
public static String word2()
{
String word = "";
Random r = new Random();
int cv = r.nextInt(3) + 1;
if(cv == 1)
{
word = "FOOD";
}
else if(cv == 2)
{
word = "MUD";
}
else if(cv == 3)
{
word = "GRAINS";
}
return word;
}
public static String word3()
{
String word = "";
Random r = new Random();
int cv = r.nextInt(3) + 1;
if(cv == 1)
{
word = "TRAM";
}
else if(cv == 2)
{
word = "BUS";
}
else if(cv == 3)
{
word = "BICYCLE";
}
return word;
}
public static String word4()
{
String word = "";
Random r = new Random();
int cv = r.nextInt(3) + 1;
if(cv == 1)
{
word = "MALL";
}
else if(cv == 2)
{
word = "PARK";
}
else if(cv == 3)
{
word = "POOL";
}
return word;
}
public void totalMemory(int mem1, int mem2, int mem3)
{
int iq = (mem1 + mem2 + mem3);
System.out.println("");
if(iq == 3)
{
System.out.println("YOU GOT THEM ALL");
}
else if(iq <= 2 || iq >= 1)
{
System.out.println("YOU MISSED A TOTAL OF " + (3 - iq));
}
else if(iq == 0)
{
System.out.println("HA! YOU MISSED THEM ALL");
}
}
}
total points is a variable from match2 class and iq from match3 class. Any help with any methods I could use to make this happen would be much appreciated. Thank You

Well ... besides the fact you are not following any code convention, Like class names should start with a capital letter and public static final fields (like totalpoints and iq) should be all Uppercase (code conventions, you are not sharring match2 and match3 codes, without it we can't understand what is happening inside those classes.
But you can do a simple test and assign a value to match2.totalpoints and match3.iq and you are going to see the summing of these two values being printed by the last system.out you put.
good luck and good Java studies!

Are the int variables you're trying to use inside child classes of your main parent class? Did you extend the child classes in your main parent class?
Class #1:
public int firstVar(int someNum) {
//code here
return someNum;
}
Class #2:
public int secondVar(int otherNum) {
//code here
return otherNum;
}
Class #3 Class with Main Method -
public class mainClass extends class#1; //etc
//code here and finally print out the finished number
You could try extending one of the classes that has an int you need into another one of the classes with the other int you need and then just extending that second class into your main, OR you could try completely redefining your classes and just placing all the ints you need into one separate class and then extending that single one into your main.

So I finally got it to work. The problem, I guess, was that I was trying to add together the variables from the other classes(match2 and match3) outside the main function within the class(match1) I was trying to add them together. All I did was move the expression adding the variables together from the top to inside the main function like this:
public static int finished;
public static void main(String[] args) throws InterruptedException {
// TODO Auto-generated method stub
Scanner s = new Scanner(System.in);
System.out.println("THIS IS YOUR OWN EXCLUSIVE IQ TEST OR MEMORY QUIZ OR WHATEVER....");
System.out.println("");
System.out.println("When taking the quiztest you have only two seconds before making each guess");
match2 m = new match2();
finished = (match2.totalpoints + match3.iq);
System.out.println("THAT MEANS ACCORDING TO YOUR QUIZTEST YOU'VE GOT AN IQ OF " + finished + " POINTS");
}
}
Thanks for all the help from everyone.

Smth. like this. You have lot's of code duplication
public class MatchRunner {
public static void main(String... args) throws InterruptedException {
new MatchRunner().start();
}
public void start() throws InterruptedException {
System.out.println("THIS IS YOUR OWN EXCLUSIVE IQ TEST OR MEMORY QUIZ OR WHATEVER....");
System.out.println();
System.out.println("When taking the quiztest you have only two seconds before making each guess");
int totalPoints = new Match2().getTotalPoints();
System.out.println("For the next part of your IQ Assesment");
System.out.println("just type back the words in CAPSLOCK in CAPSLOCK");
int iq = new Match3().getIQ();
System.out.println("THAT MEANS ACCORDING TO YOUR QUIZTEST YOU'VE GOT AN IQ OF " + (totalPoints + iq) + " POINTS");
}
}
public class Match2 {
public int getTotalPoints() throws InterruptedException {
try (Scanner scan = new Scanner(System.in)) {
int totalPoints = calc(scan, "first", "nice +1 try", "almost");
totalPoints += calc(scan, "next", "good", "almost");
totalPoints += calc(scan, "final", "great", "eeeh buzer sound");
printTotalPoints(totalPoints);
return totalPoints;
}
}
private static void countdown() throws InterruptedException {
for (int i = 5; i > 0; i--) {
Thread.sleep(750);
System.out.println(i + "...");
}
}
private static int calc(Scanner scan, String strSet, String strEqual, String strNotEqual) throws InterruptedException {
System.out.println("press ENTER for your " + strSet + " set...");
Random random = new Random();
scan.nextLine();
countdown();
int sum = 0;
for (int i = 0; i < 4; i++)
sum += random.nextInt(9) + 1;
System.out.println(sum);
for (int i = 0; i < 10; i++)
System.out.println();
int guess = scan.nextInt();
System.out.println(guess == sum ? strEqual : strNotEqual);
return guess == sum ? 1 : 0;
}
private static void printTotalPoints(int totalPoints) {
System.out.println();
if (totalPoints == 3)
System.out.println("YOU GOT THEM ALL");
else if (totalPoints <= 2 && totalPoints >= 1)
System.out.println("YOU MISSED A TOTAL OF " + (3 - totalPoints));
else if (totalPoints == 0)
System.out.println("HA! YOU MISSED THEM ALL");
}
}
public class Match3 {
public int getIQ() throws InterruptedException {
try (Scanner scan = new Scanner(System.in)) {
Random random = new Random();
Supplier<String> getWord1 = () -> getWord(random, "DOG", "CAT", "BIRD");
Supplier<String> getWord2 = () -> getWord(random, "FOOD", "MUD", "GRAINS");
Supplier<String> getWord3 = () -> getWord(random, "TRAM", "BUS", "BICYCLE");
Supplier<String> getWord4 = () -> getWord(random, "MALL", "PARK", "POOL");
int iq = calc(scan, getWord1, getWord2, "ate the");
iq += calc(scan, getWord1, getWord3, "drove the");
iq += calc(scan, getWord1, getWord4, "visited the");
printIq(iq);
return iq;
}
}
private static void countdown() throws InterruptedException {
System.out.println("READY...");
Thread.sleep(1000);
System.out.println("SET...");
Thread.sleep(1000);
}
public int calc(Scanner scan, Supplier<String> wordOne, Supplier<String> wordTwo, String strMsq) throws InterruptedException {
System.out.println("Press ENTER when ready");
scan.nextLine();
countdown();
String a = wordOne.get();
String b = wordTwo.get();
System.out.println("The " + a + ' ' + strMsq + ' ' + b);
String wordGroup = a + ' ' + b;
for (int i = 0; i <= 10; i++)
System.out.println();
String wordGuess = scan.nextLine();
System.out.println(wordGroup.equals(wordGuess) ? "awesome cock muncher a match" : "nope");
return wordGroup.equals(wordGuess) ? 1 : 0;
}
private static String getWord(Random random, String one, String two, String three) {
int cv = random.nextInt(3) + 1;
if (cv == 1)
return one;
if (cv == 2)
return two;
if (cv == 3)
return three;
return "";
}
public void printIq(int iq) {
System.out.println();
if (iq == 3)
System.out.println("YOU GOT THEM ALL");
else if (iq <= 2 || iq >= 1)
System.out.println("YOU MISSED A TOTAL OF " + (3 - iq));
else if (iq == 0)
System.out.println("HA! YOU MISSED THEM ALL");
}
}

Lonely Integer - Output is correct. But still getting additional message

Im trying to find the lonely integer in an array. My output is correct, but still getting the extra message. Please have a look at the code. I’m using Java to write the program.
Code:
import java.util.InputMismatchException;
import java.util.Scanner;
public class LonelyInteger {
private static int inputArray[];
private static int inputLength;
private static final Scanner scanner = new Scanner(System.in);;
public static void main(String[] args) {
try {
if (getInput()) {
sortAndPrintArray();
findLonelyInteger();
} else {
System.out.println("OOPS, something is not right! Try again!");
}
} catch (NumberFormatException | InputMismatchException nfime) {
System.out.print("Number Format Exception or Input Mismatch Exception Occured: " + nfime);
} catch (Exception e) {
System.out.print("Exception Occured: " + e.getMessage());
}
}
private static boolean getInput() throws NumberFormatException, InputMismatchException, Exception {
System.out.print("Enter the array length: ");
inputLength = scanner.nextInt();
if (inputLength <= 0) {
return false;
}
inputArray = new int[inputLength];
System.out.println("Enter the array:");
for (int i = 0; i < inputLength; i++) {
inputArray[i] = scanner.nextInt();
}
return true;
}
private static void sortAndPrintArray() {
sortArray();
printSortedArray();
}
private static void sortArray() {
int temp = 0;
for (int i = 0; i < inputLength; i++) {
for (int j = 0; j < i; j++) {
if (inputArray[i] < inputArray[j]) {
temp = inputArray[i];
inputArray[i] = inputArray[j];
inputArray[j] = temp;
}
}
}
}
private static void printSortedArray() {
System.out.println("Sorted Array:");
for (int i = 0; i < inputLength; i++) {
System.out.print(inputArray[i] + " ");
}
System.out.println();
}
private static void findLonelyInteger() {
boolean foundLonelyInteger = false;
for (int i = 0; i < inputLength; i++) {
if ((i+1) == inputLength) {
System.out.println("Lonely Integer: " + inputArray[i]);
break;
}
if (inputArray[i] == inputArray[++i]) {
continue;
} else {
System.out.println("Lonely Integer: " + inputArray[i-1]);
foundLonelyInteger = true;
i--;
}
}
if (!foundLonelyInteger) {
System.out.println("Lonely integer not available!");
}
}
}
Here is my output, which is seen in Command Prompt:
Output:
Enter the array length: 5
Enter the array:
1
2
2
1
2
Sorted Array:
1 1 2 2 2
Lonely Integer: 2
Lonely integer not available!

You did not set the flag, in your findLonelyInteger() method's first if condition!
if ((i+1) == inputLength) {
System.out.println("Lonely Integer: " + inputArray[i]);
foundLonelyInteger = true; // --> HERE
break;
}
Command Prompt? Start using Eclipse! And learn debugging!

Set your foundLonelyInteger = true; while you are checking for if((i+1) == inputLength)

How to return a string?

import java.util.*;
public class HangManP5
{
public static void main(String[] args)
{
int attempts = 10;
int wordLength;
boolean solved;
Scanner k = new Scanner(System.in);
System.out.println("Hey, what's your name?");
String name = k.nextLine();
System.out.println(name+ ", hey! This is a hangman game!\n");
RandomWord(word);
int len = word.length();
char[] temp = new char[len];
for(int i = 0; i < temp.length; i++)
{
temp[i] = '*';
}
System.out.print("\n");
System.out.print("Word to date: ");
while (attempts <= 10 && attempts > 0)
{
System.out.println("\nAttempts left: " + attempts);
System.out.print("Enter letter: ");
String test = k.next();
if(test.length() != 1)
{
System.out.println("Please enter 1 character");
continue;
}
char testChar = test.charAt(0);
int foundPos = -2;
int foundCount = 0;
while((foundPos = word.indexOf(testChar, foundPos + 1)) != -1)
{
temp[foundPos] = testChar;
foundCount++;
len--;
}
if(foundCount == 0)
{
System.out.println("Sorry, didn't find any matches for " + test);
}
else
{
System.out.println("Found " + foundCount + " matches for " + test);
}
for(int i = 0; i < temp.length; i++)
{
System.out.print(temp[i]);
}
System.out.println();
if(len == 0)
{
break; //Solved!
}
attempts--;
}
if(len == 0)
{
System.out.println("\n---------------------------");
System.out.println("Solved!");
}
else
{
System.out.println("\n---------------------------");
System.out.println("Sorry you didn't find the mystery word!");
System.out.println("It was \"" + word + "\"");
}
}
public static String RandomWord(String word)
{
//List of words
Random r = new Random();
int a = 1 + r.nextInt(5);
if(a == 1)
{
word=("Peace");
}
if(a == 2)
{
word=("Nuts");
}
if(a == 3)
{
word=("Cool");
}
if(a == 4)
{
word=("Fizz");
}
if(a == 5)
{
word=("Awesome");
}
return (word);
}
}
Ok, so this is my code for a hangman game, the only thing I have left to do is to get my program to randomize one of the words, which it should do in the method successfully. But the only problem I'm having is getting the String variable "word" to go back to the main class (there are errors underlining all the "word" variables in the main class).
If I could get help with either this or another way to produce a random word from a list, that would be amazing.

In java, parameters are passed by value and not by reference. Therefore, you cannot change the reference of a parameter.
In your case, you need to do:
public static String getRandomWord() {
switch(new Random().nextInt(5)) {
case 0:
return "Peace";
case 1:
return "Nuts";
// ...
default:
throw new IllegalStateException("Something went wrong!");
}
}
And in main:
// ...
String word = getRandomWord();
int len = word.length();
// ...

You can't modify the caller's reference.
RandomWord(word);
needs to be something like
word = RandomWord(word);
Also, by convention, Java methods start with a lower case letter. And, you could return the word without passing one in as an argument and I suggest you save your Random reference and use an array like
private static Random rand = new Random();
public static String randomWord() {
String[] words = { "Peace", "Nuts", "Cool", "Fizz", "Awesome" };
return words[rand.nextInt(words.length)];
}
And then call it like
word = randomWord();

How to read lines from a file and assign the lines to an array?

Currently, I'm trying to read in a .dat file and assign various lines into an array. The file will provide items like "a100" and "q80" which I will have to separate into categories by letter and then have different grades as an array for each category. Right now, this is what I have, but I'm getting a lot of run-time errors when I try various things. Is there something I'm missing here?
Some of the errors I'm having:
When I execute case 'P', it prints this out: WeightedGrades#13105f32
When I try to execute cases C, A or D, this happens: Exception in thread "main" java.lang.NoSuchMethodError: WeightedGrades.deleteGrade(Ljava/lang/String;)Z
WeightedGrades class:
public class WeightedGrades {
private String name;
private int numGrades;
private String[] grades;
public static final double ACTV_WT = 0.05, QUIZ_WT = 0.10, PROJ_WT = 0.25, EXAM_WT = 0.30, FINAL_EXAM_WT = 0.30;
public WeightedGrades(String nameIn, int numGradesIn, String[] gradesIn) {
name = nameIn;
numGrades = numGradesIn;
grades = gradesIn;
}
public String getName() {
return name;
}
public int getNumGrades() {
return numGrades;
}
public String[] getGrades() {
return grades;
}
public double[] gradesByCategory(char categoryChar) {
int count = 0;
for (int i = 0; i < grades.length; i++) {
if (categoryChar == grades[i].charAt(0)) {
count++;
}
}
double[] gradesNew = new double[count];
count = 0;
for( int i = 0; i < numGrades; i++) {
if (categoryChar == grades[i].charAt(0)) {
gradesNew[count] = Double.parseDouble(grades[i].substring(1));
count++;
}
}
return gradesNew;
}
public String toString() {
String result = "\tStudent Name: " + getName()
+ "\n\tActivities: " + gradesByCategory('A')
+ "\n\tQuizzes: " + gradesByCategory('Q')
+ "\n\tProjects: " + gradesByCategory('P')
+ "\n\tExams: " + gradesByCategory('E')
+ "\n\tFinal Exam: " + gradesByCategory('F')
+ "\n\tCourse Average: " + courseAvg();
return result;
}
public void addGrade(String newGrade) {
if (numGrades >= grades.length) {
increaseGradesCapacity();
}
grades[numGrades] = newGrade;
numGrades++;
}
public boolean deleteGrade(String gradeDelete) {
boolean delete = false;
int deleteIndex = -1;
for (int i = 0; i < numGrades; i++) {
if (gradeDelete.charAt(0) == grades[i].charAt(0) &&
Double.parseDouble(gradeDelete.substring(1))
== Double.parseDouble(grades[i].substring(1))) {
deleteIndex = i;
}
}
if (deleteIndex > -1) {
for (int i = deleteIndex; i < numGrades - 1; i++) {
grades[i] = grades[i + 1];
}
grades[numGrades - 1] = "";
numGrades--;
return true;
}
else {
return false;
}
}
public void increaseGradesCapacity() {
String[] temporary = new String[grades.length + 1];
for (int i = 0; i < grades.length; i++) {
temporary[i] = grades[i];
}
grades = temporary;
}
public double average(double[] newArray) {
if (newArray.length == 0) {
return 0.0;
}
double sum = 0;
double average = 0;
for ( int i = 0; i < newArray.length; i++) {
sum += newArray[i];
average = sum / newArray.length;
}
return average;
}
public double courseAvg() {
double actvAvg = 0.0;
double quizAvg = 0.0;
double projAvg = 0.0;
double examAvg = 0.0;
double finalAvg = 0.0;
double avg = 0.0;
if (!numGrades.length == 0) {
avg = actvAvg * ACTV_WT + quizAvg * QUIZ_WT + projAvg * PROJ_WT + examAvg * EXAM_WT + finalAvg * FINAL_EXAM_WT;
}
return avg;
}
}
Second class
import java.util.Scanner;
import java.io.IOException;
public class WeightedGradesApp {
public static void main(String[] args) throws IOException {
String name = "";
int numGrades = 0;
String[] grades = new String[13];
String code = "";
String gradeAdd = "";
String gradeDelete = "";
String categoryIn = "";
WeightedGrades student = new WeightedGrades(name, numGrades, grades);
Scanner userInput = new Scanner(System.in);
if (args == null) {
System.out.println("File name was expected as a run argument.");
System.out.println("Program ending.");
return;
}
else {
System.out.println("File read in and WeightedGrades object created.");
System.out.println("");
System.out.println("Player App Menu");
System.out.println("P - Print Report");
System.out.println("C - Print Category");
System.out.println("A - Add Grade");
System.out.println("D - Delete Grade");
System.out.println("Q - Quit ");
do {
System.out.print("Enter Code [P, C, A, D, or Q]: ");
code = userInput.nextLine();
if (code.length() == 0) {
continue;
}
code = code.toUpperCase();
char codeChar = code.charAt(0);
switch (codeChar) {
case 'P':
System.out.println(student.toString());
break;
case 'C':
System.out.print(" Category: ");
categoryIn = userInput.nextLine();
char categoryChar = categoryIn.charAt(0);
System.out.println(student.gradesByCategory(categoryChar));
break;
case 'A':
System.out.print(" Grade to add: ");
gradeAdd = userInput.nextLine();
student.addGrade(gradeAdd);
break;
case 'D':
System.out.print(" Grade to delete: ");
gradeDelete = userInput.nextLine();
boolean isDeleted = student.deleteGrade(gradeDelete);
if (isDeleted) {
System.out.println(" Grade deleted");
}
else {
System.out.println(" Grade not found");
}
break;
case 'Q':
break;
default:
}
} while (!code.equalsIgnoreCase("Q"));
}
}
}

For starters your code as is doesn't compile due to the line
if (!numGrades.length == 0) {
This is because numGrades is an int it is a primative type and therefore does not have any property length. I'm assuming what you want here is
if (numGrades != 0) {
Also as I mentioned you are not dealing with reading in the file, you supply the file name but never actually read it, I suggest you look at the Java tutorial on File IO
On this note you do the check args == null this will not check that no args are supplied, try it. what you want is args.length == 0
On your other error I have no idea how you even produced that... I'm assuming it is using an older compiled version of the class where the methods have not being written.

Java skipping a number in the sequence

This is very interesting, i notice. Before i can explain further its best i show the code and you will understand what i mean.
This is the code:
public class Qn3 {
static BigDecimal[] accbal = new BigDecimal[19];
private static Integer[] accnums = new Integer[19];
public static void main(String[] args) {
addaccount();
}
public static void addAccount() {
int i = 0, accno, input, j, check;
BigDecimal accbala;
DecimalFormat df = new DecimalFormat("0.00");
Scanner sc = new Scanner(System.in);
Scanner in = new Scanner(System.in);
accnums[1] = new Integer(1);
while (accnums.length >= count(accnums)) {
System.out.print("Enter the account number: ");
while (sc.hasNext("[0-9]{7}")) {
accno = sc.nextInt();
System.out.print("Enter account balance: ");
accbala = in.nextBigDecimal();
for (j = 0; j < accnums.length; j++) {
if (accnums[j] == null)
break;
else if (accnums[j].equals(accno)) {
break;
}
}
if (j == accnums.length) {
System.out.print("No more than 20 accounts can be added.");
} else if (accnums[j] != null) {
if ((accnums[j].equals(accno)))
System.out.println("Account already exists");
break;
} else {
accnums[j] = accno;
accbala = accbala.setScale(2, RoundingMode.HALF_UP);
accbal[j] = accbala;
check = j;
System.out.println("Current number of accounts in the system: "
+ (check + 1)
+ "\nNumber of accounts still can be added: "
+ (20 - (check + 1)));
}
}
while (!sc.hasNext("[0-9]{7}")) {
System.out.println("Wrong NRIC");
break;
}
while (accnums.length <= count(accnums)) {
System.out.println("20 accounts have already been created");
break;
}
break;
}
}
private static int count(Integer[] array) {
int count = 0;
// accnums = new Integer[] {1,2};
for (int index = 0; index < array.length; index++) {
if (array[index] != null) {
count++;
}
}
// System.out.println("You have used " + count + " slots");
return count;
}
}
So now that you have seen the code the problem that is hard to notice is this, take note of the line in the addaccount() method where
System.out.println("Current number of accounts in the system: "+(check+1)+"\nNumber of accounts still can be added: "+(20 - (check+1)));
this line the first check+1 will give me 1 then the next one gives me 3! and then the next time i run the method it gives me 4 and then again 5 and so on so forth, what is happening to 2?

You have that println in an else block, and when j == 1 you're hitting the else if case. Try removing this line
accnums[1] = new Integer (1);