如何将文件读入特定格式

Question

[Todays date]  Some text
some more text
even more text
[A different date]  Some text 
[Another different date]  More text
Final text block

[Todays date] some text some more text even more text
[A different date] some text
[Another different date] More text Final text block

如果这一行文本没有以方括号开头，我想把这一行连接到上面的一行。我可以读它在正常使用这个代码。我试着用String.StartsWith但是我搞不懂。

    List<String> testList = new ArrayList<String>();
    
    BufferedReader br = new BufferedReader(new FileReader("SystemOut.log"));
    String line = br.readLine();
    while (line!=null) {
        testList.add(line);
        line=br.readLine();
    }
    br.close();

我正在寻找对此方法的更改，以使它以我想要的格式读取它，或者可能是一个将作用于我的列表 并对此问题排序的方法。谢谢

Answer 1

一个更好的解决方案（第三次尝试），它（希望）能更好地处理大文件，避免将整个文件读入缓冲区：

    public static void main(String[] args) throws IOException {
        String input = "[04/06/2021]  Some text\n" +
                "some more text\n" +
                "even more text\n" +
                "[01/01/2020]  Some text \n" +
                "[31/12/2020]  More text\n" +
                "Final text block";


        List<String> testList = new ArrayList<>();
        try (BufferedReader br = new BufferedReader(new StringReader(input))) {
            br.lines().forEach(
                    line -> {
                        if (testList.isEmpty() || line.startsWith("[")) {
                            testList.add(line + " ");
                        } else {
                            testList.set(
                                    testList.size() - 1,
                                    testList.get(testList.size() - 1) + line + " ");
                        }
                    }
            );
        }
        testList.forEach(System.out::println);
    }

我想出了这个繁琐的方法：

    public static void main(String[] args) throws IOException {
        String input = "[04/06/2021]  Some text\n" +
                "some more text\n" +
                "even more text\n" +
                "[01/01/2020]  Some text \n" +
                "[31/12/2020]  More text\n" +
                "Final text block";

        List<String> testList = new ArrayList<>();

        try (BufferedReader br = new BufferedReader(new StringReader(input))) {
            String nextLine = br.readLine();
            StringBuilder currentLine = new StringBuilder(nextLine + " ");
            while (nextLine != null) {
                nextLine = br.readLine();
                if (nextLine != null) {
                    if (nextLine.startsWith("[")) {
                        testList.add(currentLine.toString());
                        currentLine = new StringBuilder();
                    }
                currentLine.append(nextLine).append(" ");
                }
            }
            if (currentLine.length() > 0) {
                testList.add(currentLine.toString());
            }
        }
        testList.forEach(System.out::println);
    }

如果您可以远离您的循环，那么更好/更简单的方法是：

    public static void main(String[] args) throws IOException {
        String input = "[04/06/2021]  Some text\n" +
                "some more text\n" +
                "even more text\n" +
                "[01/01/2020]  Some text \n" +
                "[31/12/2020]  More text\n" +
                "Final text block";

        List<String> testList = new ArrayList<>();

        String[] inputs = input.split("\\n");
        StringBuilder currentLine = new StringBuilder(inputs[0] + " ");
        for (int i = 1; i < inputs.length; i++) {
            if (inputs[i].startsWith("[")) {
                testList.add(currentLine.toString());
                currentLine = new StringBuilder();
            }
            currentLine.append(inputs[i]).append(" ");
        }
        testList.add(currentLine.toString());
        testList.forEach(System.out::println);
    }

[04/06/2021]  Some text some more text even more text 
[01/01/2020]  Some text  
[31/12/2020]  More text Final text block