Functional Requirements Specification 功能需求的規格
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Java float精度計算的問題,無法截取小數點後兩位
使用了網上普遍採用的幾種方式:
(一):
float a = 123.2334f;
float b = (float)(Math.round(a*100))/100;(這裏的100就是2位小數點,如果要其它位,如4位,這裏兩個100改成10000)
(二):
import java.text.DecimalFormat;
String a = new DecimalFormat("###,###,###.##").format(100.12345);
(三):
float ft = 134.3435f;
int scale = 2;//設置位數
int roundingMode = 4;//表示四捨五入,可以選擇其他舍值方式,例如去尾,等等.
BigDecimal bd = new BigDecimal((double)ft);
bd = bd.setScale(scale,roundingMode);
ft = bd.floatValue();
這幾種在打印顯示的時候都沒問題,但是在數據庫中存在的真實值(float字段,上面幾種方式在格式化後結果正確,我再轉成float後結果就錯了)並沒有截取成兩位小數,例如:0.333333343267441
在我取出數據後轉成double後就變成了真實值,而不是0.33
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public static NumberFormat getDf(){
if(df==null){
df = NumberFormat.getFormat("##,##0.00"); }
return df;
}
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decode(條件,值1,翻譯值1,值2,翻譯值2,...值n,翻譯值n,缺省值)
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set lin 5000;
spool filename
...
spool off
--執行sql導出console結果到c:/log.txt;
sqlplus ecpuser/ecpuser@EPDEV
SQL> set lin 1000;
SQL> spool c:/log.txt;
SQL> @ 5.DB_IMPORT(MEMS_PAYMENT_BILLO).sql
SQL> /
SQL> spool off;
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爲了允許兩個或兩個以上的變量控制循環,Java 允許你在for 循環的初始化部分和反覆部分聲明多個變量,每個變量之間用逗號分開。
使用逗號,前面的for循環將更高效,改寫後的程序如下:
// Using the comma.
class Comma {
public static void main(String args[]) {
int a, b;
for(a=1, b=4; a<b; a++, b--) {
System.out.println("a = " + a);
System.out.println("b = " + b);
}
}
}
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/**
* 得到本月的第一天
* @return
*/
public static String getMonthFirstDay() {
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.DAY_OF_MONTH, calendar
.getActualMinimum(Calendar.DAY_OF_MONTH));
return dateFormat("yyyy-MM-dd", calendar.getTime());
}
/**
* 得到本月的最後一天
*
* @return
*/
public static String getMonthLastDay() {
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.DAY_OF_MONTH, calendar
.getActualMaximum(Calendar.DAY_OF_MONTH));
return dateFormat("yyyy-MM-dd", calendar.getTime());
}
/**
*
* @param year
* int 年份
* @param month
* int 月份
*
* @return int 某年某月的最後一天
*/
private int getLastDayOfMonth(int year, int month) {
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, year);
cal.set(Calendar.MONTH, month);
// 某年某月的最後一天
return cal.getActualMaximum(Calendar.DATE);
}
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得到當月最大天數是getMaximum(Calendar.DAY_OF_MONTH);
得到當年最大天數是getMaximum(Calendar.DAY_OF_YEAR);
得到當月最大週數是getMaximum(Calendar.WEEK_OF_MONTH);
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int year = summaryDate.getYear();
int month = summaryDate.getMonth();
int day = summaryDate.getDate();
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, year);
cal.set(Calendar.MONTH, month);
// 某年某月的最後一天
int maxday = cal.getActualMaximum(Calendar.DATE);
if (type.equals(Constants.PAYMENT_BILL_SUMMARY_YEAR)) {
ssDate = new Date(year, 0, 1, 0, 0, 0);
esDate = new Date(year, 11, 31, 23, 59, 59);
} else if (type.equals(Constants.PAYMENT_BILL_SUMMARY_MOUTH)) {
ssDate = new Date(year, month, 1, 0, 0, 0);
esDate = new Date(year, month, maxday, 23, 59, 59);
} else if (type.equals(Constants.PAYMENT_BILL_SUMMARY_DAY)) {
ssDate = new Date(year, month, day, 0, 0, 0);
esDate = new Date(year, month, day, 23, 59, 59);
}
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方法一:
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
java.util.Date now = df.parse("2008-03-26 13:31:40");
java.util.Date date=df.parse("2008-01-02 11:30:24");
long l=now.getTime()-date.getTime();
long day=l/(24*60*60*1000);
long hour=(l/(60*60*1000)-day*24);
long min=((l/(60*1000))-day*24*60-hour*60);
long s=(l/1000-day*24*60*60-hour*60*60-min*60);
System.out.println(""+day+"天"+hour+"小時"+min+"分"+s+"秒");
方法二:
SimpleDateFormat dfs = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
java.util.Date begin=dfs.parse("2008-01-02 11:30:24");
java.util.Date end = dfs.parse("2008-03-26 13:31:40");
long between=(end.getTime()-begin.getTime())/1000;//除以1000是爲了轉換成秒
long day1=between/(24*3600);
long hour1=between%(24*3600)/3600;
long minute1=between%3600/60;
long second1=between%60/60;
System.out.println(""+day1+"天"+hour1+"小時"+minute1+"分"+second1+"秒");