JAVA知识总结

1.格式化数字

double amount= 111.0;

DecimalFormat df = new DecimalFormat("#,##0.00");

System.out.println(df.format(amount));

 

DecimalFormat  decimal = new DecimalFormat("#.00");

String dlay_intr = decimal.format(ln_dlay_intr);

 

2.迭代器

for(Iterator it = c.iterater(); it.hasNext(); ) { ... }

for(int i=0; i<array.size(); i++) { ... get(i) ... }

源文档 <http://blog.csdn.net/basenet855x/article/details/6841749>

 

3.字符串的截取(用"|"作为分隔符时,前面要加"\\")

String arr[] = strr.split("\\|");

 

4.判断一个字符串的最后一个字符是否为“,”

"sdsdsd,".endsWith(",")

 

5.StringUtils的用法

StringUtils.substring(rule, startIndex,endIndex + 1)//截取字符串

StringUtils.repeat("0", orgCodeRule.length()- 2 - orgCode.length())//重写为0

StringUtils.replace(rule, orgCodeRule, orgCodeRuleValue)//替换

 

6.indexOf的用法

"010003,010004".indexOf("010003") 返回值为0

 

7.去掉字符串里面的回车和换行符号

String sqlString = "9021405430\n062228110165\r333";

System.out.println(sqlString);

System.out.println(sqlString.replaceAll("\r", "").replaceAll("\n", ""));

 

8.

字符串和日期互转

字符串转日期

 

try{
         String sDate = "2008-04-07";
         SimpleDateFormat formate= new SimpleDateFormat("yyyy-MM-dd");
         Date date = formate.parse(sDate);
         System.out.println(date);//输出结果:Mon Apr 07 00:00:00 CST 2008
         }catch(Exception e){e.printStackTrace();}

////////////////////////////////////////////////////////////////////////////////////
 try{
         String sDate = "20080407";
         SimpleDateFormat formate= new SimpleDateFormat("yyyyMMdd");
         Date date = formate.parse(sDate);
         System.out.println(date);//输出结果:Mon Apr 07 00:00:00 CST 2008
         }catch(Exception e){e.printStackTrace();}

 

 

日期转字符串

SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMddHHmmss");

String dateString = formatter.format(new Date(System.currentTimeMillis()));

 

String sDate = "20120207";         

  SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");

            try {

                    java.util.Date date = (java.util.Date)dateFormat.parse(sDate);

                    java.sql.Date dateSql = new java.sql.Date(date.getTime());

                    System.out.println(dateSql);

} catch (Exception e) {

e.printStackTrace();

}