public class ArrayCopy
{
    public static void main(String[] args)
    {
        int size =1024*1024*5;
        int i,length = size;
        char oldArray[] = new char[size];
        char newArray[] = new char[size];
        for(i=0;i<size;i++)
            oldArray[i]=(char) i;
        long startTime = System.currentTimeMillis();        
        
        for(i=0;i<1000;i++)
        {
            selfCopy(oldArray, 0, newArray, 0, length);            //100次2475 1000次19290
            //System.arraycopy(oldArray, 0, newArray, 0, length);//        940       10225    
            //newArray=oldArray.clone();                        //        2545          25425
        
            //selfCopy(newArray, 0, newArray, 1, length-1);
            //System.arraycopy(newArray, 0, newArray, 1, length-1);
        }
        
        long endTime = System.currentTimeMillis();
        
        System.out.println("消耗时间: " + (endTime - startTime)+" ms.");
        System.out.println(new String(oldArray).substring(100,200)+"\n\n"+new String(newArray).substring(100,200));
    }

    private static void selfCopyObj(Object oldArray, int startPosOld, Object newArray, int startPosNew, int length)
    {
        for (int i = 0; i < length; i++)
        {
            ( (Object[] )newArray)[startPosNew++] = ( (Object[]) oldArray)[startPosOld++];
        }
    }
    private static void selfCopy(char[] oldArray, int startPosOld, char[] newArray, int startPosNew, int length)
    {
        for (int i = 0; i < length; i++)
        {
            newArray[startPosNew++] =  oldArray[startPosOld++];
        }
    }
}