Question

I want to create an array of a type which I create.
Here’s my problem:

public class MyFile
{        
     int page_no=23;
     Page[] pages_in_file;
     MyFile()
     {
         pages_in_file=new Page[page_no];
     }  
}

And Java gives error when debug comes to Page[] part and it does not even entes Page’s constructor.
Page Class is this:

public class Page
{  
    String data=null;
    String contain=null;

Page()
{
    data = new String();
    contain = new String();
}
}

Error says : “Source not found” and gives this NullPointerException when I try to access an element in the array.
I guess I don’t see an obvious error but i appreciate any help. Thanks

Answer 1

Java only allocates the memory for your classes, it does not run the constructors when initialising the array. At a minimum, you will need to add:

for (int i = 0; i < pages_in_file.length; i++)
    pages_in_file[i] = new Page();