Data types are frequently encountered during Java development.

(1) when int or double is converted to BigDecimal, the number of digits increases accordingly. To solve this problem, you can round the long type of double by using the self-write function round.
After conversion, convert to String, and then use new BigDecimal () to convert
   
Example: fosum = new BigDecimal (String. & #118 alueOf (round (uo1sum. double & #118 alue () + uo2sum. double & #118 alue (), 3 )))
 
(2) convert Time to characters

Java. util. Date date = new java. util. Date (databean. getTyrq (). getTime ());
SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd ");
Tyrq = sdf. format (date );

(3) convert the string to the Timestamp type
Public java. SQL. Timestamp strToTimestamp (String str ){
Java. SQL. Timestamp sdate = null;

If (str! = Null ){

If (str. trim (). length () = 8 ){
Str = str. substring () + "-" + str. substring () + "-" + str. substring );

      }
Try {
DateFormat df = DateFormat. getDateInstance (DateFormat. DEFAULT, java. util. Locale. CHINA );
Java. util. Date date = df. parse (str );
Sdate = new java. SQL. Timestamp (date. getTime ());
} Catch (Exception e ){
E. printStackTrace ();
    }

}
Return sdate;
}
 
(4) rounding the double type
Public double round (double v, int scale ){

If (scale <0 ){

Throw new IllegalArgumentException ("The scale must be a positive integer or zero ");

       }

BigDecimal B = new BigDecimal (Double. toString (v ));

BigDecimal one = new BigDecimal ("1 ");

Return B. divide (one, scale,

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