如何使用 Java DecimalFormat 强制使用小数点？

Question

I have this code with two doubles:

double a = 2000.01;
double b = 2000.00;
String pattern = "0.##";
DecimalFormat dc = new DecimalFormat(pattern); // <- "0.##" does not work
System.out.println(dc.format(a));
System.out.println(dc.format(b));

Need to a pattern that would produce the following output:

2000.01
2000.

The decimal point is present for b even though zeros are not printed

Answer 1

One option is to use 'DecimalFormat.setDecimalSeparatorAlwaysShown' to always include the decimal.

Sample:

double a = 2000.01;
double b = 2000.00;
String pattern = "0.##";
DecimalFormat df = new DecimalFormat(pattern);
df.setDecimalSeparatorAlwaysShown(true);
System.out.println(df.format(a));
System.out.println(df.format(b));

Sample Output:

2000.01
2000.

Answer 2

Use this pattern: #0.00

It should look like this:

double a = 2000.01;
double b = 2000.00;
String pattern = "#0.00";
DecimalFormat dc = new DecimalFormat(pattern);
System.out.println(dc.format(a));
System.out.println(dc.format(b));

Which prints:

2000.01
2000.00

Answer 3

extend DecimalFormat

public class MDF extends DecimalFormat {
  public String format(double d) {
    String s = super.format(d);
    if (!s.contains(".")) {
      return s + ".";
    }
    return s;
  }
}