小编Ben*_*Ben的帖子

我有一些文件解析器代码,我偶尔会在m.matches()(其中m是匹配器)上获得堆栈溢出错误.

我再次运行我的应用程序,它解析相同的文件,没有堆栈溢出.

这是真的我的模式有点复杂.它基本上是一堆可选的零长度正向前瞻,其中包含命名组,因此我可以匹配一堆变量名称/值对,而不管它们的顺序如何.但我希望,如果某些字符串会导致堆栈溢出错误,它总会导致它......不仅仅是有时......任何想法？

我的模式的简化版本 "prefix(?=\\s+user=(?<user>\\S+))?(?=\\s+repo=(?<repo>\\S+))?.*?"

完全正则表达式是......

app=github(?=(?:[^"]|"[^"]*")*\s+user=(?<user>\S+))?(?=(?:[^"]|"[^"]*")*\s+repo=(?<repo>\S+))?(?=(?:[^"]|"[^"]*")*\s+remote_address=(?<ip>\S+))?(?=(?:[^"]|"[^"]*")*\s+now="(?<time>\S+)\+\d\d:\d\d")?(?=(?:[^"]|"[^"]*")*\s+url="(?<url>\S+)")?(?=(?:[^"]|"[^"]*")*\s+referer="(?<referer>\S+)")?(?=(?:[^"]|"[^"]*")*\s+status=(?<status>\S+))?(?=(?:[^"]|"[^"]*")*\s+elapsed=(?<elapsed>\S+))?(?=(?:[^"]|"[^"]*")*\s+request_method=(?<requestmethod>\S+))?(?=(?:[^"]|"[^"]*")*\s+created_at="(?<createdat>\S+)(?:-|\+)\d\d:\d\d")?(?=(?:[^"]|"[^"]*")*\s+pull_request_id=(?<pullrequestid>\d+))?(?=(?:[^"]|"[^"]*")*\s+at=(?<at>\S+))?(?=(?:[^"]|"[^"]*")*\s+fn=(?<fn>\S+))?(?=(?:[^"]|"[^"]*")*\s+method=(?<method>\S+))?(?=(?:[^"]|"[^"]*")*\s+current_user=(?<user2>\S+))?(?=(?:[^"]|"[^"]*")*\s+content_length=(?<contentlength>\S+))?(?=(?:[^"]|"[^"]*")*\s+request_category=(?<requestcategory>\S+))?(?=(?:[^"]|"[^"]*")*\s+controller=(?<controller>\S+))?(?=(?:[^"]|"[^"]*")*\s+action=(?<action>\S+))?.*?

栈顶溢出错误堆栈...(大约9800行)

Exception: java.lang.StackOverflowError
    at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
    at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
    at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
    at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
    at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
    at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
    at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
    at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
    at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
    at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
    at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
    at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
    at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
    at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
    at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
    at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
    at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
    at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
    at java.util.regex.Pattern$Loop.match(Pattern.java:4697) …

要清楚 - 这里的目标是使用输入和输出流,这样我以后就不会为输出构建大量列表.我只是想让java打开输入文件,并运行它,在半实时写入输出文件.

我对溪流来说是全新的.我理解了stream和lamba等的基本思想,但是不知道实现和语法的细节等等(例如,我在一些例子中看到的::语法让我感到困惑)...

在任何情况下 - 下面是一个基本完成我要做的事情的例子......

我想知道如何使用流接口,以便主文件(可能非常大)不需要同时在内存中.

谢谢!

        Set<String> set1 = fileToSet(file1);
        Set<String> set2 = fileToSet(file2);

        List<String> output1 = new ArrayList<>();
        List<String> output2 = new ArrayList<>();
        List<String> output3 = new ArrayList<>();

        for (String line : Files.readAllLines(inputPath)) {
                String subString = line.substring(0,10);

                if (set1.contains(subString)) {
                    output1.add(line);
                }
                else if (set2.contains(subString)) {
                    output2.add(line);
                }
                else {
                    output3.add(line);
                }
        }
//write out all 3 files from the collected lists