用数学表达式进行Java拆分 [英] Java Splitting With Math Expression

问题描述

我正在尝试拆分数学表达式.

I am trying to split a Math Expression.

String number = "100+500";

String[] split = new String[3];

我想做

• split [0] ="100"
• split [1] ="+"
• split [2] ="500"

我尝试了这个，但是我不知道该怎么写.

I tried this but I don't know what to write for splitting.

split = number.split(????);

推荐答案

您想在数字和非数字之间进行拆分而不消耗任何输入...您需要环顾四周:

You want to split between digits and non-digits without consuming any input... you need look arounds:

String[] split = number.split("(?<=\\d)(?=\\D)|(?<=\\D)(?=\\d)");

正则表达式的火车残骸到底是什么东西?

What the heck is that train wreck of a regex?

它表示此答案的首句:

• (?< = \ d)表示前一个字符是数字
• (?= \ D)表示下一个字符为非数字
• (?< = \ d)(?= \ D)在一起将在 个数字和一个非数字
之间匹配
• regexA | regexB 表示匹配regexA 或 regexB，用作以上几点，但反之亦然，数字无数字
>

• (?<=\d) means the previous character is a digit
• (?=\D) means the next character is a non-digit
• (?<=\d)(?=\D) together will match between a digit and a non-digit
• regexA|regexB means either regexA or regexB is matched, which is used as above points, but non-digit then digit for the visa-versa logic

重要的一点是，环顾环境是不消耗的，因此拆分过程不会在拆分过程中吞噬任何输入内容.

An important point is that look arounds are non-consuming, so the split doesn't gobble up any of the input during the split.

以下是一些测试代码:

String number = "100+500-123/456*789";
String[] split = number.split("(?<=\\d)(?=\\D)|(?<=\\D)(?=\\d)");
System.out.println(Arrays.toString(split));

输出:

[100, +, 500, -, 123, /, 456, *, 789]

---

要使用可能带有小数点的数字，请使用以下正则表达式:

---

To work with numbers that may have a decimal point, use this regex:

"(?<=[\\d.])(?=[^\\d.])|(?<=[^\\d.])(?=[\\d.])"

实际上只是将.添加到作为数字"的字符上.

which effectively just add . to the characters that are a "number".

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