Library management system

 package com.company;

import java.util.Scanner;
class library{
    String [] array= new String[1000];
    String [] aray= new String[1000];
    Scanner s=new Scanner(System.in);
    int i,b;
    int g;
    int h=6;
   public void returnbook(){
       int v;
       System.out.println("enter the name of Book");
       for(i=0; i <= h; i++){
           if(array[i]==null){
               array[this.g]=s.nextLine();
           }
       }
   }
    void addbook() {
        int n = 5;
           for (i = 0; i <= n; i++) {
               System.out.println("enter the name of the book");
               array[i] = s.nextLine();
           }
        }

    void issuebook() {
        int n = 0;
        int c = 0;
        for (i = 0; i <= n; i++) {
            System.out.println("enter the number of the book you want ot issue");
            int d = s.nextInt();
            c = d - 1;
            aray[i] = array[c];
            System.out.println("book registered");
            array[c]=null;
        }
        g = c;
        for (i=0;i<6;i++){
            if(array[i]==null){
                array[i]=array[i+1];
                array[i+1]=null;
            }
        }
    }
    void issuedbooks(){
        System.out.println("\n Issued books are");
        for (i = 0; i <= b; i++) {
            System.out.println((i+1) +"-"+ aray[i]);
        }
    }
    void avialablebooks(){
        System.out.println("\n Avialable books are");
        for (i = 0; i <= 5; i++) {
            if (array[i]==null){
                this.g=i;
                break;
            }
            System.out.println((i+1) +"-"+ array[i]);
        }
    }
}
public class OnlineLibrraryManagement extends library {
    public static void main(String[] args) {
    library l=new library();
    l.addbook();
    l.avialablebooks();
    l.issuebook();
    l.issuedbooks();
    l.avialablebooks();
    l.returnbook();
        l.avialablebooks();
    }
}