Array help needed!!!

Question

import java.lang.String;
import java.io.*;
import java.io.IOException;
import java.util.*;
import java.lang.Boolean;
class Books
public static final int SIZE=3;
// public static final int LOAN;
// public static final int RETURN;
//public static final int QUERY;
static int option;
String title;
String author;
boolean loanStatus;
String borrowerID;
Date loanDate;
Date dueDate;
Books[]p0=new Books[SIZE];
static void DisplayMenu()
System.out.println("===Menu===");
System.out.println("0 to Exit");
System.out.println("1 to Borrow a book");
System.out.println("2 to Return a book");
System.out.println("3 to Query a book");
System.out.print("===Your Choice>>");
public static void main(String[] args)
throws IOException
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
String string;
Books display =new Books();
do
System.out.println("\n\n");
Date loanDate = new Date();
Date dueDate = new Date();
dueDate.setTime(loanDate.getTime() + (long)(24*60*60*1000)*14);
System.out.println(loanDate);
System.out.println(dueDate);
display.DisplayMenu();
System.out.flush();
string=stdin.readLine();
option=Integer.parseInt(string);
switch(option)
case 0:
System.out.println("Exit");
break;
case 1:
//display.displayBookList(Books[] p0)
display.displayBookList(p0);
display.loanBook();
break;
case 2:
display.returnBook();
break;
}while(option!=0);
void loanBook() throws IOException {
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
String string;
if(!loanStatus){
System.out.println("Enter borrower ID: ");
System.out.flush();
borrowerID=stdin.readLine();
loanStatus=true;
else
System.out.println("Book is on loan");
public void Books()
// Books[]p0=new Books[SIZE];
     loanStatus=false;      
p0[0]=new Books();
p0[0].title="Java Software Solution";
p0[0].author="Lewis Loftus";
p0[1]=new Books();
p0[1].title="Java How To Programming";
p0[1].author="Lewis Loftus";
p0[2]=new Books();
p0[2].title="Java";
p0[2].author="Lewis Loftus";
void returnBook()
if( loanStatus)
loanStatus=false;
System.out.println("Book is return");
else
System.out.println("Book is Not on loan");
static void displayBookList(Books[] p0)
//Books display=new Books();
System.out.println("===Book List===");
System.out.println("0 Back To Main Menu");
System.out.println("1 "+p0[0].title);
System.out.println("2 "+p0[1].title);
System.out.println("3 "+p0[2].title);
System.out.print("===Your Choice>>");
static void processBook(Books[] p0) throws IOException
System.out.flush();
string=stdin.readLine();
option=Integer.parseInt(string);
switch(option)
case 0:
display.DisplayMenu();
break;
case 1:
break;
case 2:
display.returnBook();
break;
Does anyone know how why i cant access the array???

Answer 1

Hello,
After u make p0 as display.p0 inside choice 1 in your main method u can compile the code.
But still there are some problems in ur code.
1)when u will try running it and give option as 1.
ur constructor --- public void Books() will not be called because its not a constructor at all its a method. In any case a constructor can not have a return type.
if u give a return type to a constructor as given void by u.then that constructor wil be treated as a method and when u costruct the objects default costructor will be called. So ur constructor is never called.Thats why it will
give u null pointer exception when u try to display the list of books.
2) if u remove void from ur constructor...
then also u are calling new Books() constructor again in side new Books() constructor, so it will go in to an infinite loop....
so be clear what u want to do and then proceed..
hope this will be of help.
Amrainder