Array of Classes NullPointerException

Question

This is Element class:

public class Element {

    private String elementName;
    private int atomicNumber;
    private String Symbol;
    priv         


        

Answer 1

you have only initialized the Element Array but never initialized its elements,

        Element[] element = new Element[103];
    element[0].setElementName("H");// this cause NPE as element[0] is null

You need to initialize the elements like below:

      Element[] element = new Element[103];
       element[0] = new Element();
      element[0].setElementName("H");

Answer 2

When you create an array of objects all it's elements are initialized to null. You simply have to create a new Element object and add it to the array like this:

Element[] elems = new Element[100];
elems[0] = new Element();
elem[0].setElementName("asdf");