BigDecimal common API

BigDecimal Commonly used in daily development , Some calculations involving amounts and calculations to ensure accuracy will use , Here are some common API

1、 Add add

        BigDecimal a = new BigDecimal(999);
        BigDecimal b = new BigDecimal(10000);
        a = a.add(b);
        System.out.println(a.add(b));//10999

2、 Subtraction subtract

		BigDecimal a = new BigDecimal(999);
        BigDecimal b = new BigDecimal(10000);
        a = a.subtract(b);
        System.out.println(a);//-9001

3、 Multiplication multiply

		BigDecimal a = new BigDecimal(999);
        BigDecimal b = new BigDecimal(10000);
        BigDecimal c = a.multiply(b);
        System.out.println("a*b=" + c);

4、 division divide

		BigDecimal a = new BigDecimal(999);
        BigDecimal b = new BigDecimal(10000);
        c = a.divide(b);
        System.out.println("a/b=" + c);

5、 Seeking remainder divideAndRemainder

divideAndRemainder Method will return a length of 2 Of BigDecimal Array , The first is business , The second is the remainder

		BigDecimal a = new BigDecimal(999);
        BigDecimal b = new BigDecimal(10000);
        BigDecimal[] c = a.divideAndRemainder(b);
        System.out.println("a/b=" + c[0] + " remainder " + c[1]);

6、 Compare the size compareTo

BigDecimal Can pass compareTo Methods to compare .
The result is int type ,-1 Say less than ,0 Is equal to ,1 It is greater than .

        BigDecimal a = new BigDecimal(999);
        BigDecimal b = new BigDecimal(10000);

        if (a.compareTo(b) > 0) {
    
            System.out.println("a Greater than b");
        } else if (a.compareTo(b) == 0) {
    
            System.out.println("a be equal to b");
        } else {
    
            System.out.println("a Less than b");
        }

7、 Deal with decimals

Here is the trade-off mode

• ROUND_UP ： For positive numbers, it is to discard the decimal , Add one , For negative numbers , Subtract one from the decimal . for example ：100.4, Take the integer as 101,-100.5, Take the integer as -101
• ROUND_DOWN ： Directly discard decimals or decimals after the exact place
• ROUND_CEILING : If BigDecimal It's true , Then do ROUND_UP operation ; If a negative , Then do ROUND_DOWN operation （ Take the larger integer in the vicinity ）.
• ROUND_FLOOR ： If BigDecimal It's true , Then do ROUND_DOWN operation ; If a negative , Then do ROUND_UP operation （ Take the smaller integer in the vicinity ）.
• ROUND_HALF_UP ： rounding ,0.5 Rounding up 100.5 -> 101
• ROUND_HALF_DOWN ： rounding ,0.5 Rounding down 100.5 -> 100
• ROUND_UNNECESSARY ： If there are decimal places , Just throw it ArithmeticException abnormal .

Set separately

        BigDecimal a = new BigDecimal("998.5");
        BigDecimal up = a.setScale(0, RoundingMode.UP);
        System.out.println( "up ======= " + up);
        BigDecimal down = a.setScale(0, RoundingMode.DOWN);
        System.out.println( "down ======= " + down);
        // Take the nearest larger integer 
        BigDecimal ceiling = a.setScale(0, RoundingMode.CEILING);
        System.out.println( "ceiling ======= " + ceiling);
        // Take the nearest smaller integer 
        BigDecimal floor = a.setScale(0, RoundingMode.FLOOR);
        System.out.println( "floor ======= " + floor);
        // rounding ,0.5 Rounding up 
        BigDecimal halfUp = a.setScale(0, RoundingMode.HALF_UP);
        System.out.println( "halfUp ======= " + halfUp);
        // rounding ,0.5 Rounding down 
        BigDecimal halfDown = a.setScale(0, RoundingMode.HALF_DOWN);
        System.out.println( "halfDown ======= " + halfDown);

Division application

// Two decimal places are reserved for the result 
BigDecimal divide = a.divide(b, 2, RoundingMode.UP);
System.out.println(divide);