After a few decimal floating-point processing java

Reprinted: https://blog.csdn.net/xue_feitian/article/details/6556275

the first method:

. 1  Double F = 123.2315455458 ;
 2 the BigDecimal B = new new the BigDecimal (F);
 . 3  Double F1 = b.setScale (. 3, BigDecimal.ROUND_HALF_UP) .doubleValue ();     // three decimal places, and finally a rounding 
. 4 the System.out .println (f1);

Output: 123.232

The second method:

1 DecimalFormat df = new new DecimalFormat (. "# 000");　　// # .000 three decimal places, and so on 
2 String f = df.format (123.2315452);　　　　　　　　　// rounding 
3 System.out.println (f);

Output: 123.232

The third method:

. 1  Double D = 123.2315455458 ;
 2 String String.format S = ( "% 6F.", D);     // Reserved six decimal places, the last bit rounded 
. 3  System.out.println (S);

The output is: 123.231546

% Represents any number of digits before the decimal point 6 shows the results after two decimal floating-point representation format is f