Work/test/StringArray.java

import java.lang.ArrayIndexOutOfBoundsException;

class StringArray
{
  private final int BlockSize=16;
  private int mGrowBy=BlockSize;
  private int mActualItemCount=0;
  private int mVirtualItemCount=mGrowBy;
  private String mStringArray[]=new String[mGrowBy];
  
  public String getAt(int arrayIndex)throws ArrayIndexOutOfBoundsException
  {
    if(arrayIndex>=size())throw new ArrayIndexOutOfBoundsException();
    return mStringArray[arrayIndex];
  }
  public void setAt(String strItem,int arrayIndex)throws ArrayIndexOutOfBoundsException
  {
    if(arrayIndex>=size())throw new ArrayIndexOutOfBoundsException();
    mStringArray[arrayIndex]=strItem;
  }
  public boolean insert(String strItem)
  {
    guarantee(size()+1);
    mStringArray[size()]=strItem;
    size(size()+1);
    return true;
  }
  public void guarantee(int requiredSize)
  {
    if(virtualSize()>=requiredSize)return;
    String tmpArray[]=new String[virtualSize()+growBy()];
    for(int index=0;index<virtualSize();index++)tmpArray[index]=mStringArray[index];
    mStringArray=new String[virtualSize()+growBy()];
    virtualSize(virtualSize()+growBy());
    for(int index=0;index<virtualSize();index++)mStringArray[index]=tmpArray[index];    
  }
  public int size()
  {
    return mActualItemCount;
  }
  private void size(int actualItemCount)
  {
    mActualItemCount=actualItemCount;
  }
  private int virtualSize()
  {
    return mVirtualItemCount;
  }
  private void virtualSize(int virtualSize)
  {
    mVirtualItemCount=virtualSize;
  }
  public int growBy()
  {
    return mGrowBy;
  }
  public void growBy(int growBy)
  {
    mGrowBy=growBy;
  }
  public void clear()
  {
    mStringArray=new String[growBy()];  
    size(0);
    virtualSize(growBy());
  }
}