ArrayList and homemade imitation ArrayList

Recently in the internship by the company sent to the Valley training, in the teacher's layout to do, theoretically with ArrayList is very convenient, only he has not said, I use the words have a feeling of cheating, then the whim of his own with an array to write an imitation ArrayList.

/** *  @ClassName: mylist *  @Description:  imitation arraylist*  @author  lmc*   @date  2015-11-5  pm 06:34:59 */public class mylist<t>{/** * @ fields defaultsize :  Initialize array length *  default length should be 10, for easy testing   2*/private int defaultsize  = 2;  private static final int max_array_size = integer.max _value - 8;//t[] entity;/** *  @Fields  nowSize :  Current array length */int size= 0; object[] elementdata;public mylist () {elementdata = new object[defaultsize];} Public mylist (int listsize) {if  (listsize < 0)              throw new illegalargumentexception ("Illegal Capacity:  "+            listsize);elementData =  New object[listsizE];} /** *  @Title: add  Add an element *  @Description:    */public void add ( T element) {//Determines whether the number of elements in the array exceeds the upper limit, expands the array ensurecapacityinternal (size+1),//size+1 to the required minimum capacity elementdata[size++]  = element;} /** *  @Title: get *  @Description:  Gets the first index element */public t get (int  Index) {rangecheck (index);return  (T) elementdata[index];}     /**     *  @Title: remove      *  @Description:   Remove the index element in list     *  @return  T       index Element     */    public t remove ( Int index)  {        rangecheck (index);         T oldValue =   (T) elementdata[index];         int nummoved = size - index - 1;        if  (numMoved  > 0)             system.arraycopy ( elementdata, index+1, elementdata, index,                               nummoved);        elementdata[--size] = null;  // clear to let GC do its work         return oldValue;    }/** *  @Title: size  *  @Description:    Gets the number of current data (or the length of the list) */public int size () {return size;} /** *  @Title: rangecheck *  @Description:  determine if index exceeds array range       */private void raNgecheck (Int index)  {if  (index < 0 | |  index >= this.size) throw new indexoutofboundsexception (OUTOFBOUNDSMSG (index));} /** *  @Title: outofboundsmsg *  @Description:  Array out-of-bounds hint information */private string  Outofboundsmsg (Int index)  {        return  "index:  "+index+", size:  "+this.size;    }/** *  @Title:  ensurecapacityinternal *  @Description:  To determine if the array size needs to be amplified *  @param        size  the actual number of elements in the current array */private void ensurecapacityinternal (int mincapacity)  { if (mincapacity - elementdata.length > 0) {grow (mincapacity);}} /** *  @Title: grow *  @Description:  increase the range     array size of the array to 1.5 times times the original *  (jdk1.7) new features if the expansion is still less than the minimum demand capacity, the direct expansion to the minimum demand capacity    bit operation Speed *  (jdk1.6 before) is expanded to 1.5 times times +1;*/private Void grow (int mincapacity) {int oldcapacity = elementdata.length;     int newCapacity = oldCapacity +  (oldcapacity >> 1);//object[]  newelementdata = new object[newcapacity];//system.arraycopy (elementData, 0,  newelementdata, 0, nowsize);    if  (newcapacity - mincapacity  < 0)             newcapacity =  minCapacity;        if  (Newcapacity - max_array_ size > 0)             newcapacity  = hugecapacity (mincapacity);     elementdata = arrays.copyof ( elementdata, newcapacity);    // system.out.println ("Start expanding array size");}  /** *  @Title: hugecapacity * The   capacity of the @Description:  processing expansion has exceeded the defined maximum capacity   */private static int hugecapacity (int  mincapacity)  {        if  (mincapacity < 0 )  // overflow            throw new  outofmemoryerror ();        return  (minCapacity >  max_array_size)  ?             Integer.max_value :            max_array_size ;     }}

ArrayList and homemade imitation ArrayList