在每个第n个位置拆分一个字符串 [英] Split a string, at every nth position
问题描述
我使用这个正则表达式在每个第三个位置分割一个字符串：
I use this regex to split a string at every say 3rd position:
String []thisCombo2 = thisCombo.split("(?<=\\G...)");
其中G后面的3个点表示要分割的每个第n个位置。在这种情况下，3个点表示每3个位置。例如：
where the 3 dots after the G indicates every nth position to split. In this case, the 3 dots indicate every 3 positions. An example:
Input: String st = "123124125134135145234235245"
Output: 123 124 125 134 135 145 234 235 245.
我的问题是，如何让用户控制字符串必须的位置数量分裂？换句话说，如何制作用户控制的3个点，n个点？
My question is, how do i let the user control the number of positions where the string must be split at? In other words, how do I make those 3 dots, n dots controlled by the user?
推荐答案
为了提高性能，另一种方法是在循环中使用 substring（）：
For a big performance improvement, an alternative would be to use substring() in a loop:
public String[] splitStringEvery(String s, int interval) {
int arrayLength = (int) Math.ceil(((s.length() / (double)interval)));
String[] result = new String[arrayLength];
int j = 0;
int lastIndex = result.length - 1;
for (int i = 0; i < lastIndex; i++) {
result[i] = s.substring(j, j + interval);
j += interval;
} //Add the last bit
result[lastIndex] = s.substring(j);
return result;
}
示例：
Input: String st = "1231241251341351452342352456"
Output: 123 124 125 134 135 145 234 235 245 6.
它不像 stevevls'解决方案那么短，但它是<强大>方式更有效（见下文）我认为将来更容易调整，当然取决于您的情况。
It's not as short as stevevls' solution, but it's way more efficient (see below) and I think it would be easier to adjust in the future, of course depending on your situation.
2,000 字符长字符串 - 间隔 3 。
2,000 characters long string - interval is 3.
split（（？< = \\\\。{+ count +}））性能（以毫秒为单位）：
split("(?<=\\G.{" + count + "})") performance (in miliseconds):
7, 7, 5, 5, 4, 3, 3, 2, 2, 2
splitStringEvery（）（ substring（））性能（以毫秒为单位）：
splitStringEvery() (substring()) performance (in miliseconds):
2, 0, 0, 0, 0, 1, 0, 1, 0, 0
2,000,000 字符长字符串 - 间隔 3 。
2,000,000 characters long string - interval is 3.
split（）性能（以毫秒为单位）：
split() performance (in miliseconds):
207, 95, 376, 87, 97, 83, 83, 82, 81, 83
splitStringEvery（）性能（以毫秒为单位）：
splitStringEvery() performance (in miliseconds):
44, 20, 13, 24, 13, 26, 12, 38, 12, 13
2,000,000 字符长字符串 - 间隔 30 。
2,000,000 characters long string - interval is 30.
split（）性能（以毫秒为单位）：
split() performance (in miliseconds):
103, 61, 41, 55, 43, 44, 49, 47, 47, 45
splitStringEvery（）性能（以毫秒为单位）：
splitStringEvery() performance (in miliseconds):
7, 7, 2, 5, 1, 3, 4, 4, 2, 1
结论：
splitStringEvery（）方法快得多（即使在 Java 7u6中的更改），并且当间隔变得更高时升级。
The splitStringEvery() method is a lot faster (even after the changes in Java 7u6), and it escalates when the intervals become higher.
即用型测试代码：
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