java: Splitting arithmetic expresssion into tokens

Question

您如何用空格分隔算术表达式，例如我有22+（33 * 1）这个表达式，我想用相同的字符串（返回字符串）中的运算符之间的空格来分隔它们，例如22 +（33 * 1），我使用StringTokenizer的方式

Answer 1

Your rule is simpler then you think. Probably correct java:

expr = expr.replaceAll('+', ' + ')
           .replaceAll('-', ' - ')
           .replaceAll(')', ' ) ')
           //etc
           .replaceAll(' ', '  '); //remove any double spaces added.

Answer 2

That is Not Easy. You have to parse the Expression and Build up a tree of tokens. You Finally behave like A parser. Then you recreate the Expression and insert a Space between Each element.
try to search for parsing arithmetic expressions

Answer 3

您可以使用多个String.replaceAll语句将运算符替换为带空格的运算符。