BigDecimal是不可变的，对其进行的任何操作（包括setScale（2，BigDecimal.ROUND_HALF_UP））都会生成一个新的BigDecimal。正确的代码应为

BigDecimal bd = new BigDecimal(1);
bd.setScale(2, BigDecimal.ROUND_HALF_UP); // this does change bd
bd = bd.setScale(2, BigDecimal.ROUND_HALF_UP);
System.out.println(bd);

输出

1.00

注意--由于Java 9 BigDecimal.ROUND_HALF_UP已被弃用，您现在应该使用RoundingMode.ROUND_HALF_UP。

您可以使用上舍入格式

BigDecimal bd = new BigDecimal(2.22222);
System.out.println(bd.setScale(2,BigDecimal.ROUND_UP));

希望这对你有帮助。

要在JAVA中格式化数字，可以用途：

System.out.printf("%1$.2f", d);

其中d是变量或数字
或

DecimalFormat f = new DecimalFormat("##.00");  // this will helps you to always keeps in two decimal places
 System.out.println(f.format(d));

您需要使用类似NumberFormat的内容，并使用与format对应的语言环境

NumberFormat.getCurrencyInstance().format(bigDecimal);

bigDecimal.setScale就可以了。

下面的代码可能会有所帮助。

protected String getLocalizedBigDecimalValue(BigDecimal input, Locale locale) {
    final NumberFormat numberFormat = NumberFormat.getNumberInstance(locale);
    numberFormat.setGroupingUsed(true);
    numberFormat.setMaximumFractionDigits(2);
    numberFormat.setMinimumFractionDigits(2);
    return numberFormat.format(input);
}

您可以按以下方式使用自定义注解：自定义注解

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface FormatBigDecimal {
    String format() default "0.00";
}

然后可以在字段上应用注解，并在构造函数中调用实现方法，如下所示：

public class TestClass {
   

    @FormatBigDecimal
    private BigDecimal myDecimal;
    public TestClass(BigDecimal myDecimal) throws ParseException, IllegalAccessException {
        this.myDecimal = myDecimal;
        formatBigDecimalFields();
    }

    public void setMyDecimal(BigDecimal myDecimal) {
        this.myDecimal = myDecimal;
    }

    public BigDecimal getMyDecimal() {
        return myDecimal;
    }
/**
In the above method, we are using reflection to get all the fields declared in the class. Then, we are iterating over all the fields and checking whether the @FormatBigDecimal annotation is present on the field. If it is present, we are making the field accessible and getting its value.

We are also getting the format string from the @FormatBigDecimal annotation and using it to create a DecimalFormat object with the desired format. Then, we are formatting the value of the field using the DecimalFormat object and storing the formatted value in a string.

Finally, we are parsing the formatted value back into a BigDecimal object and setting it as the value of the field.
**/
    public void formatBigDecimalFields() throws IllegalAccessException, ParseException {
        Field[] fields = this.getClass().getDeclaredFields();
        for (Field field : fields) {
            if (field.isAnnotationPresent(FormatBigDecimal.class)) {
                field.setAccessible(true);
                BigDecimal value = (BigDecimal) field.get(this);
                FormatBigDecimal formatAnnotation = field.getAnnotation(FormatBigDecimal.class);
                String formatString = formatAnnotation.format();
                NumberFormat format = NumberFormat.getNumberInstance(Locale.US);
                DecimalFormat decimalFormat = (DecimalFormat) format;
                decimalFormat.applyPattern(formatString);
                String formattedValue = decimalFormat.format(value);
                BigDecimal formattedDecimal = new BigDecimal(formattedValue);
                field.set(this, formattedDecimal);
            }
        }
    }

}

使用方法：

TestClass testClass = new TestClass(new BigDecimal("10000.899"));
        System.out.println(testClass.getMyDecimal());

将给予：10000.90