如何显示文件中的所有文本行而不是停在行尾？

Question

下面的代码只调出第一行代码就停止了。我想return每一行代码，直到没有更多。

private String GetPhoneAddress() {
    File directory = Environment.getExternalStorageDirectory();
    File myFile = new File(directory, "mythoughtlog.txt");
    //File file = new File(Environment.getExternalStorageDirectory() + "mythoughtlog.txt");
    if (!myFile.exists()){
        String line = "Need to add smth";
        return line;
    }
    String line = null;
    //Read text from file
    //StringBuilder text = new StringBuilder();
    try {
        BufferedReader br = new BufferedReader(new FileReader(myFile));
        line = br.readLine();
    }
    catch (IOException e) {
        //You'll need to add proper error handling here
    }
    return line;
}

Answer 1

你可以遍历 readLine() 的结果并累积它们直到你得到 null，表示文件结束（顺便说一句，请注意你的代码片段忽略了关闭 reader. try-with-resource 结构可以解决这个问题):

try (BufferedReader br = new BufferedReader(new FileReader(myFile))) {
    String line = br.readLine();
    if (line == null) {
        return null;
    }
    StringBuilder retVal = new StringBuilder(line);
    line = br.readLine();
    while (line != null) {
        retVal.append(System.lineSeparator()).append(line);
        line = br.readLine();
    }
    return retVal.toString();
}

如果您使用的是 Java 8，则可以使用新引入的 lines() 方法节省大量此类代码：

try (BufferedReader br = new BufferedReader(new FileReader(myFile))) {
    return br.lines().collect(Collectors.joining(System.lineSeparator()));
}

Answer 2

一个相当简洁的解决方案：

try (BufferedReader br = new BufferedReader(new FileReader(myFile))) {
    StringBuilder retVal = new StringBuilder();
    while ((line = br.readLine()) != null) {
        retVal.append(line).append(System.lineSeparator());
    }
    return retVal.toString();
}

如何显示文件中的所有文本行而不是停在行尾？

How to display all lines of text from a file instead of stopping at the end of a line?

java

string

android

file

bufferedreader