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Add elements with arguments in an array with java

I want to add a new element that has several arguments in an array. I know how to add with just one argument, but with more i don't know.
My code is:
private Calculate[] calculation;
public Element(int numElements) {
calculation = new Calculate[numElements];
}
public void addElement(Date elementDate, double price, ElementType type) {
int numElements = elements.length;
int i = 0;
if (i < numElements) {
Calculate[i] = calculation.elementDate;
Calculate[i] = calculation.price;
Calculate[i] = calculation.type;
i++;
}
}

Calculate[i] = calculation.elementDate;
Calculate[i] = calculation.price;
Calculate[i] = calculation.type;
You shouldn't assign to the same array index 3 times. You're overriding what you've just set.
Try this (Calculate should have a constructor):
Calculate[i] = new Calculate(elementDate, price, type);
You're also maintaining an index i, but you're not looping over anything. i is just incremented from from zero to one and is not really used (apart from an almost useless conditional check).
I suggest you read over a beginners Java tutorial. You seem to be missing a lot of the fundamentals, and Stack Overflow is not a place where we should have to show you how to write a for-loop. It's well-documented and demonstrated in a tonne of tutorials already.

I assume Calculate is a class defined else where with a constructor
There is a couple of issues in this piece of code:
You want to update the array, but specify array. Calculate[] is the array type. The name if the array is calculation. The other thing is that you are trying to access calculation.elementDate etc. but since that is an array, it does not have the field elementDate. I assume your Calculate class has that field. Also, you are not applying a loop. So currently your code will only update the array on index 0.
My code:
public void addElement(Date elementDate, double price, ElementType type) {
for(int i = 0; i < elements.length; i++) { // for loop over all elements in your array
Calculate calculate = new Calculate(elementDate, price, type) // I assume this constructor is available to initialize the Calculate object
calculation[i] = calculate;
}
Hope this helps.

int cannot be converted to int []

new to programming here and i keep getting the error message, incompatible types, int cannot be converted to int [], the question is to add R1 & R2 together if they are of equal lengths and if not, print a message that says 'the arrays must be same length', if that matters, not sure where im going wrong, any help would be greatly appreciated
public int[] arrayAdd(int[] R1, int[] R2)
{
int[] sumArray= new int[R1.length];
if( R1.length!= R2.length)
{
System.out.println("The arrays must be same length");
}
else
{
for(int i=0; i< R1.length; i++)
for (int j=0; j<R2.length; j++)
{
sumArray= R1[i]+ R2[j]; // Error
}
}
return sumArray;
}

not sure where im going wrong
You are attempting to assign an int to a variable whose type is int[].
That is not legal ... and it doesn't make sense.
This:
sumArray= R1[i]+ R2[j];
should be this
sumArray[something_or_other] = R1[i] + R2[j];
... except that you have a bunch of other errors which mean that a simple "point fix" won't be correct.
Hint: you do not need nested loops to add the elements of two arrays.

sumArray[i]= R1[i]+ R2[j]; // updated line
you need to assign to an array element, but you were doing it wrong.

Your code is broken in many several ways, at least:
You declared returning an array but what is the value of it when inputs are of the wrong size? Manage such errors in better ways (stop, throw exception, return error code, etc). At least never display something at this place, this is not the place were you have to tackle the error, this is the place here you detect it, just report it to caller(s).
You (tried to) created space for the returned value but how could this be if conditions for having a return value is not met?
You used Java syntax to declare an array, int []sumArray should be `int sumArray[0].
You can't dynamically allocate an array like this, to capture a dynamic allocation you must use a pointer, an array is not a pointer. But a pointer can be set to the memory address of an allocated array, like int *sumArray = new int[10]
sumArray is an array so to set an element of it use sumArray[index] = ...
So this may be better:
public int *arrayAdd(int[] R1, int[] R2) {
if( R1.length!= R2.length) {
return nullptr;
}
int *sumArray= new int[R1.length];
for(int i=0; i< R1.length; i++) {
sumArray[i] = R1[i]+ R2[i];
}
return sumArray;
}
After question editing
If you want to sum two arrays, element by element, then a single loop is sufficient...

Actually in that line sumArray is an integer array and you are assigning it as integer only and also you haven't declared variable j.
Try this-
public int[] arrayAdd(int[] R1, int[] R2)
{
int[] sumArray= new int[R1.length];
if( R1.length!= R2.length)
{
System.out.println("The arrays must be same length");
}
else
{
for(int i=0; i< R1.length; i++)
{
sumArray[i]= R1[i]+ R2[i]; // Error
}
}
return sumArray;
}

Sum of ArrayList in a method

I'm new to coding. My task is to get a total duration of all tracks in a playlist (in seconds). There is an accessor method called getDur in another class. There is also toString method that converts everything into seconds. This is my code.
private ArrayList<Track> tracksN;
public int getDurTotal()
{
for (Track b: tracksN)
{
int sum = 0;
for (int i=0; i<tracksN.size();i++)
{
sum += tracks.get(getDur(i));
}
}
return sum;
}
However, I'm getting an error message that says "method getDur in class PlayList cannot be applied to given type. Required: no arguments; Found: int; reason: actual and formal argument lists differ in length".

Your code is iterating over the track list twice. One of the for loops needs to go. Either:
int sum = 0;
for (int i = 0; i < tracksN.size(); i++) {
Track track = tracksN.get(i);
sum += track.getDur();
}
Or
int sum = 0;
for (Track track : tracksN) {
sum += track.getDur();
}
Between these two approaches, the second approach is better as it will work correctly (with good performance) with all List<> types, not just with ArrayList<>. It's also simpler.

You need to get the track from the list, then call getDur on that. Try this:
private ArrayList<Track> tracksN;
public int getDurTotal()
{
for (Track b: tracksN)
{
int sum = 0;
for (int i=0; i<tracksN.size();i++)
{
sum += getDur(tracks.get(i));
}
}
return sum;
}

You just want to use one for loop
int sum = 0;
for (Track track : tracksN)
{
sum += track.getDur();
}
return sum;

The answer to that is in the error itself; read it again. PlayList cannot be applied to given type. Required: no arguments
Meaning you called getDur(i) with argument i.
But if you can scroll through your code and find the method getDur doesn't need any parameter.
I bet it just looks something like getDur(){ or something and it's return type I assume is int.
So if you can show the code for you class PlayList maybe someone can help you implement you code properly.

Array in Method Header: error ']' expected (Java)

I'm quite new to arrays and methods, and I've been seeing this error recurring through several programs: error '[' expected.
In each occasion, it seems to correct itself as I adjust something else, but in this particular case, I am completely stumped.
By the way, I am using several methods and arrays to create a quiz (before you ask, yes, this is an assignment and I agree, a list is a better way to handle this data - but that is not an option).
It is possible that I am not passing the arrays correctly between methods, as I'm a little muddy on that process. From my understanding, in order to send/receive (i.e. import/export) an array or other variable between methods, I must declare that variable/array in the method header parameters.
import java.util.Scanner;
public class H7pseudo
{
public static void main(String[] args)
{
//call getAnswerkey method
getAnswerkey(answerkey[i]);
//call getAnswers method
getAnswers(answers[i]);
//call passed method? necessary or no?
boolean passed = passed(answerkey[i], answers[i], qMissed[i], points);
//Print results of grading
if (passed)
{
System.out.println("Congratulations! You passed.");
}
else
{
System.out.println("Try again, sucka. You FAILED.");
}
//call totalPoints
totalIncorrect(points);
//call questionsMissed
questionsMissed(qMissed[i]);
}
//get answer key (create answerkey array & export)
public static void getAnswerkey(answerkey[i])
{
//create answerkey array here
char[] answerkey;
//determine number of questions (indices)
answerkey = new char[20];
//input values (correct answers) for each index
//for our purposes today, the answer is always 'c'.
for (int i = 0; i <=20; i++)
{
answerkey[i] = 'c';
}
}
//get student answers (create answers array & export)
public static void getAnswers(answers[i])
{
//initialize scanner for user input
Scanner scan = new Scanner(System.in);
//create answer array here
char[] answers;
//determine number of questions (indices)
answers = new char[20];
//prompt for user input as values of each index
for (int i = 0; i <= 20; i++) {
answers[i] = scan.nextChar();
}
}
//grade student answers (import & compare index values of arrays:answers&answerkey
//create & export qMissed array
public static boolean passed(answerkey[i], answers[i], qMissed[i], points)
{
int points = 0;
//create new array: qMissed
boolean[] qMissed;
//determine number of questions to be graded
qMissed = new boolean[20];
//initialize values for array
for (int i = 0; i <= 20; i++) {
qMissed[i] = false;
}
//cycle through indices of answerkey[i] & answers[i];
for (int i = 0; i =< 20; i++)
{
if (answers[i] == answerkey[i])
{
correct = true;
points = points+1;
qMissed[i] = true;
}
else {
qMissed[i] = false;
}
}
//evaluate whether or not the student passed (15+ correct answers)
if (points >= 15)
{
passed = true;
}
else
{
passed = false;
}
return passed;
}
public static void totalIncorrect(points)
{
int missed = 20 - points;
System.out.println("You missed " + missed + " questions.");
}
public static void questionsMissed(qMissed[i])
{
// for each index of the array qMissed...
for (int i = 0; i < qMissed.length; i++)
{
//...print correct and false answers.
system.out.println(i + ": " + qMissed[i] + "\n");
}
}
}

You can't define array size in the method signature, in Java.

public static void getAnswerkey(answerkey[i])
You can't put anything inside the [] in a method declaration. Also, you have to mention the type:
public static void getAnswerKey(char[] answerkey)
This is not the only reason your code won't work as intended, but I'll leave the rest as part of the exercise.

Look at your method definitions:
public static void questionsMissed(qMissed[i])
This is wrong. You should define the type of the variable and it should not contain [i] like an element of an array. It should be something like this:
public static void questionsMissed(int qMissed)
Or if you want to pass the array, write it like this:
public static void questionsMissed(int[] qMissed)
Apart of this, there are other several errors in your code:
getAnswerkey(answerkey[i]); //answerkey is not defined
getAnswers(answers[i]); //answers is not defined
It would be better if you start reading a Java tutorial first.

I want to vote up Luiggi's answer, but I don't have enough reputation to do that :)
Congrats, cordivia, on getting started with Java!
Here is how an array is declared:
type[] arrayName = new type[numberOfElements]
For example, you did this right in your method definition for getAnswerkey():
char[] answerkey;
answerkey = new char[20];
The part in the method definition inside the parentheses defines the kind of data the method is willing to accept from the outside. So if you don't need to put something into the method to get something out of it, you don't need to put anything in the parentheses. Define the method like this:
getAnswerkey() {
...But that's not the whole story. If you want to get something out of the method, it needs to have a return type as well. A return type is what you're gonna get out of the method when the method's done doing it's magic. For example, if you want to get an int array out of a method you would do something like this:
public static int getTheInteger() {
Since you want an array of chars from the method, you'll want to do something like this:
public static char[] getAnswerkey() {
So that's how you get a method to give you something back. If don't want anything back, you put void:
public static void noMarshmallows() {
Now, when you use the method, you're gonna need to do something with what it gives you, or it did all that work for nothing. So you need to store the return value in a variable when you call the array (calling methods is what you've been doing in main). You know how to store something in a variable. You use the '=' operator:
int myVeryFavoriteNumber;
myVeryFavoriteNumber = 5;
So, you do the same thing when you're getting something out of an array. You assign the return value to a variable. If you want to do this with an array, do this:
int[] myFavs;
myFavs = getMyFavoriteNumbers();
Same with chars:
char[] answerKey;
answerKey = getAnswerKey();
Voila! Your answer key is now right out in the open for the rest of main to see :)
Now, if you want to put something into a method and have it do something with what you put in, you define a parameter. You know how this works. It's just like declaring a variable, and that's exactly what it is. Parameters go in the parentheses and only the method using the parameter sees that variable name (it's local). Something like this:
public static void plusOneToAll (int[] numbers) {
for (int i = 0; i < numbers.length; i++) {
numbers[i] = numbers[i] + 1;
}
}
Notice int[] numbers in the parentheses. The type being passed in is int[] or integer array. numbers is just the parameter name. It functions just like a variable, but it is declared locally (inside the parentheses) and use locally (inside the method). So, if you wanted to compare the answers from two arrays and return the number of matches (like a total score for instance), you would do something like this:
public static int getTotalScore (char[] correctAnswers, char[] userAnswers) {
int totalScore = 0;
for (int i = 0; i < correctAnswers.length; i++) {
if (userAnswers[i] == correctAnswers[i]) {
totalScore = totalScore + 1;
}
}
return totalScore;
}
Notice the return type: int (written before the method name). Inside the array I'm using the variable totalScore to keep track of the number of times the answers match. The method takes two char arrays from the outside and uses them on the inside. Finally, I return an int: totalScore. That kicks the value of totalScore back out to whatever called it (main).
If I might add one last thing: Do yourself a favor and go pick up a copy of Head First Java. It's hard to find a good tutorial online and Java textbooks are just plain boring. The Head First series are kind of like coloring books for adults.
Best of luck!

printing a string from an array

Write a static method named listCountriesOfOrigin, to be added to the Bowl class, which is passed an array of Bowl objects, and prints to the console in a column the country of origin of each of Bowl objects in the array.
This is my code but is not right and the only compilation errors I am getting is "The system has detected compilation errors." So it is not helping me much. Am i on the right path?
public static String listCountriesOfOrigin (Bowl[] bowls) {
for(int i = 0; i < Bowl.length; i++) {
String origin = bowls[i].getOrigin();
return origin;
}
}
(.getOrigin) is already a declared method that returns the origins of the objects from the array.

for(int i = 0; i < Bowl.length; i++) // `Bowl` is the object name
shouldn't this be
for(int i = 0; i < bowls.length; i++) // bowls is the name of the array of Bowl objects passed to your method.
Also there should not be a return statement inside your for. According to your requirements, your method should print those values on the console.
Hence, make your method return void and instead of the return in the for loop, have a System.out.println(origin);