I'm trying to run my class file which has a main method in Netbeans, and I get this error.
Exception in thread "main" java.lang.NullPointerException
at javaapplication1.Magazine.main(Magazine.java:25)
What's the issue? For clarity, each Magazine has an some Supplements so I have tried to create an array of Supplements to store in one instance of a magazine.
I also don't fully understand the reason behind using a main method in a class. How would I make use of it in the main program?
Magazine.java:
//
//
// Generated by StarUML(tm) Java Add-In
//
// @ Project : Untitled
// @ File Name : Magazine.java
// @ Date : 21/04/2020
// @ Author :
//
//
package javaapplication1;
public class Magazine {
private String magazinename;
private int WeeklyCost;
private Supplement[] supplement;
private Magazine magazineobj;
public static void main(String args[]){
Supplement[] supplements = new Supplement[3];
for(Supplement supplement: supplements){
supplement.fillArray();
}
Magazine magazineobj = new Magazine("The Wheels Special", 35, supplements);
magazineobj.printMagazine();
};
public void SetMagazineName(String magazinename1){
magazinename = magazinename1;
};
public void SetWeeklyCost(int WeeklyCost1){
WeeklyCost = WeeklyCost1;
};
public String GetMagazineName(){
return magazinename;
};
public int GetWeeklyCost(){
return WeeklyCost;
};
public void SetMagazine(String magazinename1, int WeeklyCost1, Supplement[] supplements1){
magazinename = magazinename1;
WeeklyCost = WeeklyCost1;
supplement = supplements1;
};
public Magazine(String magazinename1, int WeeklyCost1, Supplement[] supplements1){
SetMagazine(magazinename1,WeeklyCost1,supplements1);
};
public Magazine(){};
public void printMagazine(){
System.out.println(magazineobj);
}
}
Supplement.java:
//
//
// Generated by StarUML(tm) Java Add-In
//
// @ Project : Untitled
// @ File Name : Supplement.java
// @ Date : 21/04/2020
// @ Author :
//
//
package javaapplication1;
public class Supplement {
private String supplementname;
private int WeeklySupCost;
Supplement[] supplements = new Supplement[3];
public void fillArray(){
supplements[0] = new Supplement("Sports Illustrated Special", 4);
supplements[1] = new Supplement("Health and Nutrition", 2);
supplements[2] = new Supplement("Lifestyled", 5);
supplements[3] = new Supplement("Gamer's Update", 3);
};
public void SetSupplementName(String supplementname1){
supplementname = supplementname1;
};
public void WeeklySupCost(int WeeklySupCost1){
WeeklySupCost = WeeklySupCost1;
};
public String GetSupplementName(){
return supplementname;
};
public int GetWeeklyCost(){
return WeeklySupCost;
};
public void SetSupplement(String supplementname1, int WeeklySupCost1){
supplementname = supplementname1;
};
public Supplement(String supplementname1, int WeeklySupCost1){
SetSupplement(supplementname1, WeeklySupCost1);
};
public Supplement(){};
}
