Question

This is my Java program , where i am setting the Objects with in the for loop as shown

ArrayList list = new ArrayList();
for(int j = 0;j<=4;j++)
{
Student student = new Student();
studunt.name="Ravi";
list.add(student);
}

Then i need to parse this List and set it inside a StudentResponse ( Which is consisting of a Student[])

StudentResponse  response = new StudentResponse();

    for (int in = 0; in < list.size(); in++) {
    {
    Student data = (TopListsQuoteData) list.get(in);
    response. student[in] = data;
    }

This is my StudentResponse class

public class StudentResponse 
{
public  Student[] student;
}

I am getting a NullPointerException at this line
response. student[in] = data;

Please help , Thanks .

Answer 1

You need to initialize the array before you can use it. Something like this:

StudentResponse  response = new StudentResponse();
response.student = new Student[list.size()];
for (int in = 0; in < list.size(); in++) {
{
    Student data = (TopListsQuoteData) list.get(in);
    response. student[in] = data;
}

Also i would suggest to use the iterator of the list instead of accessing the items by index. This works, but I feel it’s not so clean and definitely not as efficient.