arrays - why am i getting error: "Exception in thread "main" java.lang.NullPointerException" -

arrays - why am i getting error: "Exception in thread "main" java.lang.NullPointerException" -

when run programme next error:

exception in thread "main" java.lang.nullpointerexception @ study.calendar.homeworkdiary.<init>(homeworkdiary.java:51) @ study.calendar.homeworkteftinterface.main(homeworkteftinterface.java:18) java result: 1 build successful (total time: 1 second)

despite best efforts cannot identify problem believe have way declaring program.

could please help identifying , providing solution problem much appreciated.

here problem code: interface class:

public class homeworkteftinterface { public static void main(string[] args) { homeworkdiary tefo = new homeworkdiary("test"); string task1 = joptionpane.showinputdialog("task"); string subject1 = joptionpane.showinputdialog("subject"); double priorty1 = (double.parsedouble(joptionpane.showinputdialog("priorty"))); int day1 = parseint(joptionpane.showinputdialog("due day")); int month1 = parseint(joptionpane.showinputdialog("month")); int year1 = parseint(joptionpane.showinputdialog("year")); tefo.addtask(task1, subject1, priorty1, day1, month1, year1); } }

the next class:

public homeworkdiary(string filename) { // system.out.println("test5"); diary = new homework[count + 50]; count = 0; // system.out.println("test6"); seek { scanner file = new scanner(new file("homework.txt")); file.usedelimiter("#"); while (file.hasnextline()) { // system.out.println("test3"); string task = file.next(); string subject = file.next(); // system.out.println("test7"); string priorty = file.next(); // system.out.println("test9"); string day = file.next(); string month = file.next(); string year = file.next(); // system.out.println("test"); diary[count].settaks(task); diary[count].setsubject(subject); diary[count].setprioity(double.parsedouble(priorty)); diary[count].setday(parseint(day)); diary[count].setmonth(parseint(month)); diary[count].setyear(parseint(year)); // system.out.println("test 10"); count++; file.nextline(); } } grab (filenotfoundexception f) { } system.out.println("test4"); } public void addtask(string task1, string subject1, double priorty1, int day1, int month1, int year1) { diary[count].settaks(task1); diary[count].setsubject(subject1); diary[count].setprioity(priorty1); diary[count].setday(day1); diary[count].setmonth(month1); diary[count].setyear(year1); count++; }

and final array class , relevant methods:

public class homework { private string subject; private string task; private double priorty; private int year; private int month; private int day; homework(string task, string subject, double priorty, int year, int month, int day) { this.task = task; this.subject = subject; this.priorty = priorty; this.year = year; this.month = month; this.day = day; } public void settaks(string task1) { system.out.println(task1); task = task1; } public void setsubject(string subject1) { system.out.println("test"); subject = subject1; } public void setprioity(double priorty1) { priorty = priorty1; } public void setday(int day1) { day = day1; } public void setyear(int year1) { year = year1; } public void setmonth(int month1) { month = month1; }

these pieces of code not finish classes rather methods fell relevant question.

you have array diary null references of homework before using diary[count] have first initialize diary[count]=new homework(); in homeworkdiary constructor.

java arrays string int double