---------------------------------------------保留2位小数------------------------------------------------
//--- new BigDecimal(3.333).setScale(2, RoundingMode.HALF_UP).floatValue(); //-- new DecimalFormat("##0.00").format(3.335); //-- (float)Math.round(3.335*100)/100;
---------------------------------------------日期------------------------------------------------
Date date = new Date(); // 格式化日期 SimpleDateFormat sf = new SimpleDateFormat("yyyy.MM.dd G 'at' HH:mm:ss z"); String format = sf.format(date); // 日期运算 Calendar cal = Calendar.getInstance(); cal.setTime(date); // 加天 cal.add(Calendar.DATE, 100); Date time = cal.getTime();
---------------------------------------------随机数------------------------------------------------
// method1 Random ran = new Random(); int nextInt = ran.nextInt(10); // method12 int i = (int) (Math.random() * 10);
------------------------------------------正则表达式-------------------------------------------------
Pattern patt = Pattern.compile("[0-9]{4}\\-[0-9]{2}\\-[0-9]{2}"); Matcher matcher = patt.matcher(d); while(matcher.find()){ String group = matcher.group(); System.out.println(group); }