Java in Sjbarraylist itself simple implementation ArrayList

/**

* Implement ArrayList yourself

* @author Zyyt

*

*/

public class Sjbarraylist {

Storing elements in the Sjbarraylist

Transient object[] elementdata;

How many elements are in a sjbarraylist

private int size;

Construction method

Public Sjbarraylist () {

This (10);

}

Public sjbarraylist (int initialcapacity)

{//Initialize the Elementdata

if (initialcapacity > 0) {

This.elementdata = new Object[initialcapacity];

} else if (initialcapacity = = 0) {

This.elementdata = new Object[0];

} else {

throw new IllegalArgumentException ("Illegal capacity:" +

initialcapacity);

}

}

Determines whether the sjbarraylist contains an element if it does not contain an element that returns true if it contains false

public Boolean isEmpty () {

return size = = 0;

}

Returns the number of elements contained in this sjbarraylist

public int size () {

return size;

}

Add an Element

public void Add (Object obj)

{

if (size = = Elementdata.length) {

object[] Array = new object[size * 2 +1];

system.arraycopy (elementdata, 0, array, 0, elementdata.length);

elementdata = array;

}

elementdata[size++] = obj;

}

Gets the element in the corresponding index

Public Object get (int index) {

if (index<0 | | index >= size) {

System.out.println ("Index exceeds the maximum index value or index is less than 0");

return null;

}

return Elementdata[index];

}

Delete the value of the corresponding index

Public Object Remove (int index) {

if (Index < 0 | | | index > Size) {

System.out.println ("Index less than 0, or out of bounds");

System.exit (0);

}

Object OldValue = this.get (index);

System.arraycopy (elementdata, index + 1,elementdata, index, size);

elementdata[size--] = null;

return oldValue;

}

Pick up the values in the corresponding index

Public Object Set (int index,object obj)

{

if (Index < 0 | | | index > Size) {

System.out.println ("Index less than 0, or out of bounds");

System.exit (0);

}

Object OldValue = this.get (index);

Elementdata[index] = obj;

return oldValue;

}

Empty sjbarraylist

public void Clear () {

for (int i=0;i<size;i++) {

Elementdata[i] = null;

}

size = 0;

}

public static void Main (string[] args) {

Sjbarraylist sjblist = new Sjbarraylist ();

Sjblist.add ("111");

Sjblist.add ("2222");

Sjblist.add ("3333");

Sjblist.add ("4444");

Sjblist.add ("5555");

Sjblist.add ("66666");

Sjblist.remove (2);

System.out.println (Sjblist.get (3));

for (int i=0;i<sjblist.size (); i++) {

System.out.println (Sjblist.get (i));

}

}

}

Java in Sjbarraylist itself simple implementation ArrayList