How to run one Java class and then another Java class in Eclipse?

Question

I know it may be weird question but I'm really stuck. I have simple program with two classes. I need pass array from class A to class B. I did it but I cannot test it because I have no idea how to run program. When I click on the run then only one class started. I wanted test whole program and cannot find anything how to do it. Is there any command or something which say run class A and then class B? Without it I cannot test class B because values from Array (class A) are not loaded :/ Hope you understand what I mean.

I'm using eclipse.

Thanks!

Class MarkCalculator

import java.util.Scanner;

public class MarkCalculator {

public static int[] exam_grade = new int[6];
public static int[] coursework_grade = new int[6];
public static int[] coursework_weight = new int[2];
public static int[] module_points = new int[6];
public static String module_grade, holder;
public static int counter1 = 0, counter2 = 0;

public static void main(String[] args) {

Scanner input = new Scanner (System.in);

for (int i=0; i<3; i++){

    System.out.printf(i+1+". Modelue"+" Enter grade of exam:");

    while (!input.hasNextInt() ){

        System.out.printf("Enter only numbers! Enter grade of your exam: ");
        input.next();
    }

    exam_grade[i]=input.nextInt();

    System.out.printf(i+1+". Modelue"+" Enter grade of coursework:");

    while (!input.hasNextInt()){

        System.out.printf("Enter only numbers! Enter grade of your coursework: ");
        input.next();
    }

    coursework_grade[i]=input.nextInt(); 
}


computeMark(coursework_grade, exam_grade, module_points);


// calculate module grade
for(int i = 0 ;i < 3; i++){

    if (module_points[i] < 35){
        System.out.println(i+1+".Module: Fail");
    }

    else if (module_points[i] >= 35 && module_points[i] <= 40){
        System.out.println(i+1+".Module: Pass by compensation");
        counter1++;
    }

    else {
        System.out.println(i+1+".Module: Pass");
        counter2++;
    }


}

holder = computeResult(module_points, counter1,counter2, module_grade);
System.out.println("Your stage result is: "+ holder);


input.close();
}



public static int[] computeMark (int coursework_grade[], int exam_grade[], int module_points[]){

coursework_weight[0]= 50;
coursework_weight[1]= 50;

for(int i=0;i<3;i++)
{

    if (coursework_grade[i] < 35 || exam_grade[i] < 35){

        module_points[i]=(coursework_grade[i]*coursework_weight[0] + (exam_grade[i]*(100-coursework_weight[1])))/100;

        if (module_points[i] > 35){
            module_points[i] = 35; } 

        else {
            module_points[i] = 0;
        }

    }

    else {
        module_points[i]=((coursework_grade[i]*coursework_weight[0] + (exam_grade[i]*(100-coursework_weight[1])))/100); }


}

return module_points;       
}

public static String computeResult (int module_points[], int counter1, int                 counter2,     String module_grade ){

int sum = 0;
double average = 0;

for (int i = 0; i < 3; i++){

    sum = sum + module_points[i];
    average = sum / 3;
}

for (int i = 0; i < 3; i++){


    if (counter2 == 3){
        module_grade = "Pass";
    }

    else if (average >= 40 && counter1 <= 2) {
        module_grade = "Pass by compensation";
    }

    else {
        module_grade = "Fail";
    }



}

return module_grade;






}



}

Class StudentChart

public class StudentChart {

public static void main(String[] args) {


    for (int i = 0; i < 3; i++){
        System.out.println(MarkCalculator.coursework_weight);
    }




}

}

Have you created a main method to use as a driver to test both methods? — Matt Penna
– Matt Penna, Commented Nov 13, 2013 at 18:56
One of your classes in the project must have a main method, and then you click the little green run button (green circle with white 'play' arrow), or in the menu select Run->Run or Run->Debug. — Paul Richter
– Paul Richter, Commented Nov 13, 2013 at 18:56
This looks like a complete misunderstanding of how Java classes work. Post some code and we'll be able to help. — Dani
– Dani, Commented Nov 13, 2013 at 18:57
What's the purpose of the second class? What can't you do in the first class, that you would need a second class? — Paul Samsotha
– Paul Samsotha, Commented Nov 13, 2013 at 19:08

Paul Samsotha · Accepted Answer · 2013-11-13 19:12:52Z

3

You only need one main method.

class A {
    String s;

    public A(String s){
        this.s = s;
    }
}

public class B {
    public static void main(String[] args){
        A a = new A("Hello");
        System.out.println(a.s + " world!");
    }
}

class B will be the application program, the one with the main method. It will get values from class A. class A does not need to run for class B app to work, even though it uses values from class A.

edited Nov 13, 2013 at 19:12

answered Nov 13, 2013 at 19:00

Paul Samsotha

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Comments

Robin Green · Accepted Answer · 2013-11-13 19:15:39Z

1

You can have a method with a different name in another class, and call that method from your main method.

Do not call it public static void main though - that should only be used for standalone programs. If the method requires some other code to be run prior to it, it should not be the main method of a Java program.

answered Nov 13, 2013 at 19:15

Robin Green

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1 Comment

Robin Green Over a year ago

@user2956231 great, you can mark this answer as accepted by clicking the check mark / tick mark next to it.

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