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After validation, program is running successfully and storing the user input into last_name variable. But when I am trying to put last_name in the student Array, it gives me a null-pointer exception.If I omit the third line inside the for loop, the program is running fine. Here, "setStudentLastName" is a void method inside the Student class that accepts a string parameter 

//Create a array using the data from user

Student student[] = new Student[numOfStudents];

for(int i=0;i<student.length;i++)
{
  int j = i+1;
  last_name = Validator.validUpperCase(sc,"Enter student "+j+" last Name: ");
  student[i].setStudentLastName(last_name);
}
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1  
??What language platform - Java I think...? Also, post your Student class code especially the setStudentLastName() method. Without that we cannot say what is going on. –  hagubear yesterday
1  
have u initialized your array –  Exbury yesterday
    
you allocate the array to hold the items but not the items themselves. –  Hogan yesterday

1 Answer 1

up vote 4 down vote

You have to initialize the object array in order to access it

for(int i=0;i<length;i++)
{
    student[i]=new student();
}

in your code add

for(int i=0;i<student.length;i++)
  {
       int j = i+1;
       last_name = Validator.validUpperCase(sc,"Enter student "+j+" last Name: ");
       student[i]=new student();
       student[i].setStudentLastName(last_name);

  }
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