如何将十进制数字格式化为2或3位数字？

Question

I'm writing a convertor by Eclipse and my results are with 9 or 10 decimal digits and I want to make it 2 or 3. This is part of my code:

double gr = 0;
if (edtGr.getText().toString().length() > 0) {
    gr = Float.parseFloat(edtGr.getText().toString());
}
if (edtNgr.getText().toString().length() > 0) {
    gr = (Double.parseDouble(edtNgr.getText().toString())) / 1000000000;
}

edtNgr.setText("" + (gr * 1000000000));
edtGr.setText("" + gr);

This code converts grams to nanograms and I want the result in 2 or 3 decimal digits.

Answer 1

Try

String.format("%.2f", gr * 1000000000);

For 3 decimal places,

String.format("%.3f", gr * 1000000000);

Answer 2

For 2 Decimal places change your code as

edtNgr.setText(""+ ((String.format("%.2f", (gr * 1000000000)))));
edtGr.setText("" + ((String.format("%.2f", gr))));

And for 3 Decimal points

  edtNgr.setText("" + ((String.format("%.3f", (gr * 1000000000)))));
  edtGr.setText("" + ((String.format("%.3f", gr))));

Also You can use DecimalFormat . One way for (using 3 points) to use it:

 DecimalFormat df = new DecimalFormat();
 df.setMaximumFractionDigits(3);
 edtNgr.setText("" + df.format(gr * 1000000000));
 edtGr.setText("" +df.format(gr));

Please see more at How to format Decimal Number in Java

Answer 3

You can use

double roundOff = Math.round(yourDouble * 1000.0) / 1000.0;

Another way

BigDecimal doubleVal = new BigDecimal("123.13698");
BigDecimal roundOff = doubleVal.setScale(2, BigDecimal.ROUND_HALF_EVEN);

Answer 4

You can use NumberFormatter like

NumberFormat formatter = NumberFormat.getInstance();
formatter.setMaximumFractionDigits(3);

then format it like

formatter.format(36.55468865)

This will give the output 36.555 rounding off 55468865 to 555

Answer 5

(double)Math.round(value * 100000) / 100000.. the number of precision indicated by the number of zeros.

Or

double d = 12345.2145;

BigDecimal bd = new BigDecimal(d).setScale(3, RoundingMode.HALF_EVEN); d = bd.doubleValue();

Change the 1st argument in setScale method as per the precision required.