Yes, it was. Thank you very much for your help :) How could I forget that? Regards...
JA 2010/4/2 Jorge Bernal <[email protected]> > > Hello, > I think the problem is this: > you create a new StudentRecord but you don't assign the object to the > Student > > public Student(String name, double mathG, double englisG, double scienceG, > int id){ > StudentRecord st=new StudentRecord(); > st.setName(name); > st.setMathGrade(mathG); > st.setEnglishGrade(englisG); > st.setScienceGrade(scienceG); > *this.studentRecord = st;* > this.studentID=id; > increaseStudentCount(); > } > > 2010/4/2 Juan Antonio Fernandez <[email protected]> > >> Hello, >> >> I´m trying to do the exercise of Lab 1014 and I´ve got a problem. >> >> Here is my code. >> >> ////////STUDENT CLASS/////// >> >> public class Student { >> private StudentRecord studentRecord; >> private int studentID; >> private static int studentCount = 0; >> >> public Student(String name, double mathG, double englisG, double >> scienceG, int id){ >> StudentRecord st=new StudentRecord(); >> st.setName(name); >> st.setMathGrade(mathG); >> st.setEnglishGrade(englisG); >> st.setScienceGrade(scienceG); >> this.studentID=id; >> increaseStudentCount(); >> } >> >> >> public StudentRecord getStudentRecord(){ >> return this.studentRecord; >> } >> >> >> public int getstudentID(){ >> return this.studentID; >> } >> >> >> public static int getStudentCount(){ >> return studentCount; >> } >> >> public static void increaseStudentCount(){ >> studentCount++; >> } >> >> >> /////MAIN CLASS////// >> >> public class Main { >> public static void main(String[] args){ >> Student student1 = new Student("Juan",9,7,5,1); >> Student student2 = new Student("Maria",6,4,8,2); >> Student student3 = new Student("Luis",8,4,3,3); >> >> /** >> * Printing student details >> */ >> >> System.out.println("Student ID: "+student1.getstudentID()); >> System.out.println("Name: >> "+student1.getStudentRecord().getName()); <------------ HERE IS THE ERROR >> >> System.out.println("Total number of students: >> "+Student.getStudentCount()); >> } >> } >> >> When I compile the main class I receive the following error on the >> highlighted line. >> >> Student ID: 1 >> Exception in thread "main" java.lang.NullPointerException >> at Main.main(Main.java:21) >> Java Result: 1 >> BUILD SUCCESSFUL (total time: 0 seconds) >> >> I guess that the problem is that since I create a new studentRecord object >> inside the Student constructor when I try to access to that object it >> doesn´t exists anymore or something like that. As far as I understand the >> exercise I must create a Student object which creates a StudentRecord object >> and then print information about both objects. If I want to use proper >> encapsulation but I do not know how to do it. >> >> Could you help me? >> >> Regards >> >> JA >> -- >> To post to this group, send email to >> [email protected] >> To unsubscribe from this group, send email to >> [email protected]<javaprogrammingwithpassion%[email protected]> >> For more options, visit this group at >> http://groups.google.com/group/javaprogrammingwithpassion?hl=en >> > > -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/javaprogrammingwithpassion?hl=en To unsubscribe, reply using "remove me" as the subject.
