How to solve the problem of lack of precision from JAVA long to double?

In the

scenario, the data inventory is in sub-units, such as 100 points in 1 metadata inventory. Then the front-end display is meta-unit. So when you take it out, you have to convert the number of type long into double.

how to break the situation of 0.88-0.05 = 0.83000000000.1?

Java
Feb.28,2021
< H1 > use the BigDecimal data type as follows: < / H1 > 
public class MoneyUtil {

    /**
     * Translates the String repre sentation of a BigDecimal into a BigDecimal.
     */
    private static final BigDecimal ONE_HUNDRED = new BigDecimal("100");

    /**
     * 
     * @param fen 
     * @return 
     */
    public static String fenToYuan(String fen){
        // ,;
        // ,
        BigDecimal divide = new BigDecimal(fen).divide(ONE_HUNDRED, 2, 7);
        return divide.toString();
    }

    /**
     * 
     * @param yuan 
     * @return 
     */
    public static String yuanToFen(String yuan){
        BigDecimal multiply = new BigDecimal(yuan).multiply(ONE_HUNDRED);
        return String.valueOf(multiply.intValue());
    }
}
< H1 > so it's OK to store String type in your database. < / H1 >

you can subtract and then divide. (88-5) / 100

you can use the large number type of Java, for example, in BigDecimal
database, you can store it as decimal type

money will generally use BigDecimal
to intercept it by String.

after getting the data inventory figures, use BigDecimal 

        BigDecimal price1 = new BigDecimal(88 / 100.0);
        price1 = price1.setScale(2, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal price2 = new BigDecimal(5 / 100.0);
        price2 = price2.setScale(2, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal res = price1.subtract(price2);
        System.out.println(res);

clipboard.png

The

BigDecimal.setScale () method is used to format the decimal point
setScale (1) to retain one decimal place. By default, the excess decimal places are deleted directly by rounding
setScale (1Magi BigDecimal.ROUNDDown). For example, 2.35becomes 2.3BigDecimal.ROUNDplaceUP rounding processing, and 2.35becomes 2.4BigDecimal.ROUNDplaceUp) rounding. 2.35 becomes 2.3, if it is 5, then rounding down
setScale (1MagneticBigDecimal.ROUNDgroundCEILING) is close to positive infinity rounding
setScale (1mceBigDecimal.ROUndeveloping floor) approaching negative infinity, the number > 0 is the same as ROUND_UP, and the number < 0 is the same as ROUND_DOWN
rounding off to the nearest number, if it is with two numbers.

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1bf2435-31df2.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1bf2435-31df2.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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