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       Èç:
    public class Father
    {
             public void speak()
             {
               System.out.println("Father");
             }                  
    }
   public class Son extends Father
    {
             public void speak()
             {
               System.out.println("son");
             }                  
    }
ÕâÒ²½Ð×ö¶à̬ÐÔ,ÖØÐ´·½·¨Ö»ÄÜ´æÔÚÓÚ¾ßÓм̳йØÏµÖÐ,ÖØÐ´·½·¨Ö»ÄÜÖØÐ´¸¸Àà·Ç˽Óеķ½·¨,
  
    µ±ÉÏÀýÖÐ FatherÀà speak()·½·¨±»privateʱ,SonÀ಻ÄÜÖØÐ´ FatherÀà speak()·½·¨,´ËʱSonÀà speak()·½·¨Ï൱ÓëÔÚSonÀàÖж¨ÒåµÄÒ»¸öspeak()·½·¨.
FatherÀà speak()·½·¨Ò»µ«±»finalʱ,ÎÞÂ۸÷½·¨±»public,protected¼°Ä¬ÈÏËùÐÞÊÎʱ,SonÀà¸ù±¾²»ÄÜÖØÐ´ FatherÀà speak()·½·¨,ÊÔͼ±àÒë´úÂëʱ,±àÒëÆ÷»á±¨´í.Àý:
   public class Father
    {
          fianl   public void speak()
             {
               System.out.println("Father");
         &


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public class MemoryExp {
public static void main(String[] args) {
System.out.println("Total Memory"+Runtime.getRuntime().totalMemory());
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String source = "xxx.xls";
InputStream is = new FileInputStream(source);
Workbook rwb = Workbook.getWorkbook(is);
Sheet sheet = rwb.getSheet(0);
for (int i = 1; i < sheet.getRows(); i++) {
for (int j = 1; j < sheet.getColumns(); j++) {
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  long end = System.currentTimeMillis();
  System.out.println(end-start);
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