Shipra Jain

• Nov 19th, 2007

 

First of all, you create an arraylist and after that you  can perform adding, modifying, deleting data in this arraylist. This will work without collection framework

dgshivas

 Profile Answers by dgshivas 

• Feb 25th, 2008

 

when ever you try to use arrayList ,indirectly you are using Collection frame work.List implements Collection interface

SMART_PRATEEK2001

 Profile Answers by SMART_PRATEEK2001 

• Aug 1st, 2008

 

/* This only adds & removes the elts from an arraylist */
class myArrayListSecond
{
 private static int maxsize;
 private static Object data[];
 private static int index;

 public myArrayListSecond()
 {
  maxsize = 5;
  data = new Object[5];
  index=-1;
 }

 public void add(Object obj)
 {
  int totalelts = index + 1;
  
  // 1. if size is exceeding then increase the size (call reallocate method)
  // 2. increment the index
  // 3. add the current element
  if (totalelts == maxsize)
  {
   reallocate(); 
  }
  index++;
  data[index] = obj;
 }

 public void reallocate()
 {
  // 1. Store the value of maxsize in another variable (oldsize)
  // 2. increment the value of maxsize by 5
  // 3. Allocate a new array of objects of maxsize (newdata)
  // 4. Copy the contents of data array into newdata
  // 5. Finally assign the reference of newdata to data
  int oldsize = maxsize;

  maxsize = maxsize + 5;

  Object newdata[] = new Object[maxsize];
  for (int i=0;i<oldsize;i++)
  {
   newdata[i] = data[i];
  }
   data = newdata;
 }

 public void remove(int pos)
 {

  // 1. Check whether the position exists in the array or not
  // 1-->1. if pos > index then deletion not possible
  // 1-->2. if pos < index then deletion is possible
  // 2. To delete the element at that pos start a loop from that position & shift all the elements at right
    // to the left 
  // 2-->1.Finally decrement the value of index after iteration stops

  if (pos > index)
  {
   System.out.println(" Deletion not posssible ");
   System.exit(0);
  }
  
  else
  {
   
   System.out.println();

   System.out.println(" elt at " + pos + " is " + data[pos]);

   for (int i=pos;i<=index;i++)
   {
    data[i] = data[i+1];
   }
   index--;
  }
 }

 public static void disp()
 {
  int totalelts = index + 1;

  System.out.println();
  System.out.println();

  System.out.println(" The total number of elements are " + totalelts);

  System.out.println();

  System.out.println(" The size allowed is " + maxsize);

  System.out.println();

  System.out.println(" The contents of the ArrayList are ");

  for (int i=0;i<totalelts;i++)
  {
   System.out.println();
   System.out.print(data[i]);
  }
 }
}
class myArrayListMain
{
 public static void main(String[] args)
 {
  myArrayListSecond arrlist = new myArrayListSecond();

  String s1 = new String("a");  // index 0

  String s2 = new String("b");  // index 1

  String s3 = new String("c");  // index 2 

  String s4 = new String("d");  // index 3

  String s5 = new String("e");  // index 4

  String s6 = new String("f");  // index 5

  String s7 = new String("g");  // index 6

  String s8 = new String("h");  // index 7

  String s9 = new String("i");  // index 8

  String s10 = new String("j"); // index 9

  String s11 = new String("k"); // index 10

  String s12 = new String("l"); // index 11

  String s13 = new String("m"); // index 12

  String s14 = new String("n"); // index 13

  String s15 = new String("o"); // index 14

  String s16 = new String("p"); // index 15

  System.out.println(" Elements before deletion are ");

  arrlist.add(s1);
  arrlist.add(s2);
  arrlist.add(s3);
  arrlist.add(s4);
  arrlist.add(s5);
  arrlist.add(s6);
  arrlist.add(s7);
  arrlist.add(s8);
  arrlist.add(s9);
  arrlist.add(s10);
  arrlist.add(s11);
  arrlist.add(s12);
  arrlist.add(s13);
  arrlist.add(s14);
  arrlist.add(s15);
  arrlist.add(s16);

  arrlist.disp(); 

  arrlist.remove(2);

  arrlist.disp();   

  arrlist.remove(3);

  arrlist.disp();   

  arrlist.remove(4);

  arrlist.disp();   

  arrlist.remove(6);

  arrlist.disp();   
 }
}