Several methods of preserving post-decimal digits in Java

A few recent experiments, some of which require that the data submitted by the form be converted to double, is a simple function that is straightforward and straightforward double.parsedouble (Request.getparameter ("Chinese"). Trim ()) can be achieved, But because it is statistical results, so need to retain two decimal places, so a variety of Baidu found a lot of solutions, here deliberately summarized under, in case later used again?

returns the double type of the

1. Can be rounded

1 double d = 114.145; 2 D = (double) Math.Round (d * +)/+; 3 System.out.println (d);

2. Bigdecimal.round_half_up means rounding, Bigdecimal.round_half_down is also five six in, bigdecimal.round_up means carry processing (is directly plus 1), Bigdecimal.round_down means to remove the mantissa directly.

1 double d = 114.145; 2 New BigDecimal (d); 3 D = B.setscale (2, bigdecimal.round_half_up). Doublevalue ();         4 System.out.println (d);

Returns a string of type

1.#.00 means to retain the post two bits, it is processed by directly cutting off the mantissa, not rounding.

1 double d = 114.145; 2 New DecimalFormat ("#.00"); 3 String str = Df.format (d); 4 System.out.println (str);

2.%.2f means that after two bits are retained, it is handled in a way that is also directly truncated and not rounded.

1 double d = 114.145; 2 String.Format ("%.2f", D);

3.roundingmode.half_down six, negative number first to take the absolute value and then five six into the negative, roundingmode.half_up: for rounding, negative number first to take the absolute value of five six into the negative.

1 double d = 114.1452 numberformat nf = numberformat.getnumberinstance (); 3 // keep two decimal places 4 nf.setmaximumfractiondigits (25//  If rounding is not required, you can use Roundingmode.down  6nf.setroundingmode (roundingmode.up); 7 System.out.println (Nf.format (d));

Several methods of preserving post-decimal digits in Java