The pitfalls of Java BigDecimal

1. The pit of the constructor

public void constructTest(){

   BigDecimal value1 =new BigDecimal(10.511);
   System.out.println("value1: " + value1);
   BigDecimal value2 = new BigDecimal("10.511");
   System.out.println("value2: " + value2);

}

According to our expectation, the output of value1 should be 10.511, but the actual value is not like this, as follows:

value1: 10.510999999999999232613845379091799259185791015625
value2: 10.511

When we use double data as a parameter, the constructed BigDecimal object value1 does not guarantee the accuracy of the data. 
When constructing an object with String as a parameter, the accuracy of the data is guaranteed.

 

2. BigDecimal immutability pit

BigDecimal has the same object immutable line as String, once assigned, it will not change.

public void immutableTest() {

   BigDecimal count = new BigDecimal("1.3");
   count.add( new BigDecimal("9.2"));
   System.out.println("count:" + count);

}

count:1.3

Executing the code will find that count is not the expected 10.5, or the initial assignment 1.3 
BigDecimal must save the result when doing the operation.