Java implements double to retain two decimal places after the decimal point

1. Return double type

1. Can be rounded

double d = 114.145;
d = (double) Math.round(d * 100) / 100;
System.out.println(d);

2. BigDecimal.ROUND_HALF_UP means rounding, BigDecimal .ROUND_HALF_DOWN is also rounded, BigDecimal.ROUND_UP means carry processing (that is, adding 1 directly), and BigDecimal.ROUND_DOWN means directly removing the mantissa.

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double d = 114.145;
BigDecimal b = new BigDecimal(d);
d = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();        
System.out.println(d);

2 returns String type

1, # .00 means retaining the last two digits. Its processing method is to directly truncate the unnecessary mantissa without rounding.

double d = 114.145;
DecimalFormat df = new DecimalFormat("#.00");
String str = df.format(d);
System.out.println(str);

2. %.2f means retaining the last two digits and can be rounded off.

double d = 114.145;
String.format("%.2f", d);

3. RoundingMode.HALF_DOWN means rounding, negative numbers first take the absolute value, then rounding, and then negative numbers. RoundingMode.HALF_UP: means rounding, negative numbers first take the absolute value, then rounding, and then negative numbers.

double d = 114.145
NumberFormat nf = NumberFormat.getNumberInstance();
// 保留两位小数
nf.setMaximumFractionDigits(2); 
// 如果不需要四舍五入，可以使用RoundingMode.DOWN
nf.setRoundingMode(RoundingMode.UP);
System.out.println(nf.format(d));

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