writing array values to another class

[ronald christian]

hi all,

basic query here, i have a simple array that collects 6 values from the prompt and stores them in an array, this works fine (see code 1 below) when i create the array in the same class, what i need to do is initialize the array in another class and send the values back to that class from this class. i have tried declaring the array in another classed called MyMarks and then in the class below writing MyMarks marks= new MyMarks(); and removing the array declaration, but I keep getting symbol not found errors, any pointers on the correct syntax?? I need to use this other class beacuse I have to put more methods in there that work on the data sent..

-----code 1 ----------

class MyMarksMain {
	
    public static void main(String[] args){
    	
    	double [] mymarks = new double [5];	

		SimpleInput keyboard = new SimpleInput();
	 	
	             System.out.println("enter result 1 =  ");
		mymarks[0] = keyboard.nextDouble();
		System.out.println("enter result 2 =  ");
		mymarks[1] = keyboard.nextDouble();
		System.out.println("enter result 3 =  ");
		mymarks[2] = keyboard.nextDouble();
		System.out.println("enter result 4 =  ");
		mymarks[3] = keyboard.nextDouble();
		System.out.println("enter result 5 =  ");
		mymarks[4] = keyboard.nextDouble();
   				}				
        }

[Paul Richards]

Are you saying you need to copy an array? Or copy the values from one array to another? Sorry, I am a little unclear on what your problem is.

[ronald christian]

hi paul,

i need these values to get stored in the array that is in the other class MyMarks, the question was to basically put the array, methods etc.. in one class and just get the input and display the results in the other class, it is to practice using getters and setters rather than putting it all together. hope this is a bit clearer.

[ianjedi]

from what you wrote I think you need to do it in the construtor and create a new instance of the array and then use getter and setter method.

[ronald christian]

can you give us a quick example???? cheers

[ianjedi]

Class Myarray {



public Myarray(int i){

double [] mymarks = new double [i];

}

}

From another class

Myarray marks= new Myarray(5);

and some method as a setter/getter

[ronald christian]

hi ianjedi,

cheers for the quick replies,

it gives me cannot find symbol error when i call the array from the other class using Myarray marks= new Myarray(5);

[ianjedi]

did you make a construtor in the class? As the new instance in other class can only be made by the constructor from the my array class. You know what is meant by constructor?

cheers

Ian G

[ronald christian]

hi ian,

i changed the names slightly to match the filenames/requirements etc.. and put

StudentMarks marks= new StudentMarks(5);

i also recomplied the origonal class as well, the error says

canot find symbol

symbol : constructor StudentMarks(int)
location : class StudentMarks


so it looks like it is going back to the original array class StudentMarks which i changed to read

public void StudentMarks(int i){

double [] marks = new double [i];

[ianjedi]

mine was just an example of how to make a class with a construtor.

StudentMarks marks= new StudentMarks(5);

you would need a class StudentMarks, with a construtor StudentMarks(int i);

then an array inside the constructor to be initialize to i or could be set at 5 if that is th size you need.

[ronald christian]

Hi ian,

i think i have all that, see below, but it still gives the cannot find symbol error when i try to compile the other class ??? is it because i have not assigned the getter setter methods to handle the values??? i thought this might not be required at this point???

i have a class called studentMarks and inside it i have

class StudentMarks {
public static void main(String[] arg) {

}

// Create the array
public void StudentMarks(int i){

double [] marks = new double [i];

}

[ianjedi]

sorry the void should not be there I made a mistake which I edit.

[ronald christian]

cheers ian, that error is not coming any more! but it is giving an

array required, but StudentMarks found

marks[0] = keyboard.nextDouble();

and putting the arrow under the opening square bracket after the s on marks

[ianjedi]

can you post your code thanks.

[ronald christian]

this is StudentMarksMain

class StudentMarksMain {
	
    public static void main(String[] args) {
    	    		
        StudentMarks marks= new StudentMarks(7);
		
		SimpleInput keyboard = new SimpleInput();
	 	
	    System.out.println("enter result 1 =  ");
		marks[0] = keyboard.nextDouble();
		System.out.println("enter result 2 =  ");
		marks[1] = keyboard.nextDouble();
		System.out.println("enter result 3 =  ");
		marks[2] = keyboard.nextDouble();
		System.out.println("enter result 4 =  ");
		marks[3] = keyboard.nextDouble();
		System.out.println("enter result 5 =  ");
		marks[4] = keyboard.nextDouble();
		System.out.println("enter result 6 =  ");
		marks[5] = keyboard.nextDouble();
	    System.out.println("enter result 7 =  ");
		marks[6] = keyboard.nextDouble();
		
		System.out.println("result 1 =" + marks[0]);
		System.out.println("result 2 =" + marks[1]);
		System.out.println("result 3 =" + marks[2]);
		System.out.println("result 4 =" + marks[3]);
		System.out.println("result 5 =" + marks[4]);
		System.out.println("result 6 =" + marks[5]);
		System.out.println("result 7 =" + marks[6]);
		
		
   				}

this is StudentMarks

class StudentMarks {
	public static void main(String[] arg) {
		
	}
	
	// Create the array 
	public StudentMarks(int i){

	double [] marks = new double [i];

}

[ianjedi]

StudentMarks marks= new StudentMarks(7);

try to change that to new StudentMarks(7);

I don't have compliler on this computer, but I think it may work like that.

[ronald christian]

hi ian,

it gives a different error,

cannot find symbol
symbol : variable marks

cheers

[ianjedi]

I'll post later when I go home as this computer only has a web browser.

someone else may have beat me to it in that time :)
cheers

Ian J

[Supamagier]

You should use

marks.marks[0] = blabla

instead of

marks[0] = blabla

And this:

class StudentMarks {
	public static void main(String[] arg) {
		
	}
	
	// Create the array 
	public StudentMarks(int i){

	double [] marks = new double [i];

}

should be

class StudentMarks {

	public double[] marks;
	// Create the array 
	public StudentMarks(int i){

	marks = new double[i];
}

}

[ronald christian]

hi supamagier,

i get an illegal start of expression error when i compile

class StudentMarks {


// Create the array
public StudentMarks(int i){

public double [] marks = new double [i];
}

}