[英]Java: Using Regular Expressions to Extract various number of values in a String
I want to write a function to extract various number of values from a String according to a regex pattern: 我想编写一个函数,根据正则表达式模式从String中提取不同数量的值:
Here is my function code: 这是我的功能代码:
/**
* Get substrings in a string using groups in regular expression.
*
* @param str
* @param regex
* @return
*/
public static String[] regexMatch(String str, String regex) {
String[] rtn = null;
if (str != null && regex != null) {
Pattern pat = Pattern.compile(regex);
Matcher matcher = pat.matcher(str);
if (matcher.find()) {
int nGroup = matcher.groupCount();
rtn = new String[nGroup];
for (int i = 0; i < nGroup; i++) {
rtn[i] = matcher.group(i);
}
}
}
return rtn;
}
When I test it using: 当我使用以下方法测试时:
String str = "nets-(90000,5,4).dat";
String regex = "(\\d+),(\\d+),(\\d+)";
String[] rtn = regexMatch(str, regex);
I get: 我明白了:
rtn: [90000,5,4,90000,5]
How can I get rtn to be [90000,5,4] as I expected? 我怎么能像我预期的那样得到rtn [90000,5,4]?
Your array currently store 您的阵列当前存储
[0] -> 90000,5,4
[1] -> 90000
[2] -> 5
That is why you are seeing as output [90000,5,4,90000,5]
. 这就是为什么你看到输出
[90000,5,4,90000,5]
。 It is because group(0)
represents entire match so it returns 90000,5,4
. 这是因为
group(0)
表示整个匹配,因此它返回90000,5,4
。
What you need is match from groups 1, 2 and 3. 你需要的是第1,2和3组的匹配。
(\\d+),(\\d+),(\\d+)
1 2 3
So change 所以改变
rtn[i] = matcher.group(i);
to 至
rtn[i] = matcher.group(i+1);
First, I would start the for loop with 1 so you can get the grouping you are declaring in your regex. 首先,我将以1开始for循环,这样你就可以得到你在正则表达式中声明的分组。 The loop should look like this:
循环应如下所示:
for (int i = 1; i <= nGroup; i++) {
rtn[i] = matcher.group(i);
}
Group 0 is known to be the entire matching string for your regex. 已知组0是正则表达式的完整匹配字符串。 The grouping is from:
分组来自:
String regex = "(\\d+),(\\d+),(\\d+)";
You would say matcher.group(1), matcher.group(2), and matcher.group(3) will give you what you want. 你会说matcher.group(1),matcher.group(2)和matcher.group(3)会给你你想要的东西。
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