When using the index to access the array obtained by the split method of String, you need to
check whether there is any content after the last separator , otherwise there is a risk of throwing IndexOutOfBoundsException.
Expansion:
Explanation: For the assignment of Integer var =? Between -128 and 127, the Integer object is generated in IntegerCache.cache and
will reuse the existing object. The Integer value in this range can be directly judged by using ==, but All data outside this range
will be generated on the heap, and existing objects will not be reused. This is a big pit, and it is recommended to use the equals method for judgment.
Any currency amount is stored in the smallest currency unit and integer type.