java - InputstreamReader 只读取一行？

Question

我在主要 Activity 的 onCreate() 方法中编写了以下内容。

file = new File(this.getFilesDir(), SIMPLE_WORKOUTS);
    writeToFile("Test1, 20, 10, 5, 2, 1", this);
    writeToFile("Test2, 10, 5, 2, 1, 1", this);
    writeToFile("Test3, 1, 1, 2, 3, 5", this);
    String readFrom = readFromFile(this);
    Log.e("TAG", readFrom);

但是，字符串 readFrom 永远只等于“Test3, 1, 1, 2, 3, 5”。我希望能够将多行代码存储在一个文件中，并逐行读取文件。 writeToFile 和readFromFile 方法如下:

public void writeToFile(String data, Context context) {
    String existing = readFromFile(context);
    try (OutputStreamWriter fos = new OutputStreamWriter(context.openFileOutput(SIMPLE_WORKOUTS, Context.MODE_PRIVATE))) {

        fos.write(data + "\n");

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public String readFromFile(Context context) {

    String ret = "";

    try {
        InputStream inputStream = context.openFileInput(SIMPLE_WORKOUTS);

        if ( inputStream != null ) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String receiveString = bufferedReader.readLine();
            StringBuilder stringBuilder = new StringBuilder();

            while ( receiveString != null ) {
                stringBuilder.append(receiveString).append("\n");
                receiveString = bufferedReader.readLine();
            }

            inputStream.close();
            ret = stringBuilder.toString();
        }
    }
    catch (FileNotFoundException e) {
        Log.e("login activity", "File not found: " + e.toString());
    } catch (IOException e) {
        Log.e("login activity", "Can not read file: " + e.toString());
    }

    return ret;
}

为什么 inputstreamreader 只读取写入文件的最后一行？或者，Scanner 是否更适合我的目标？

Answer 1

需要以append方式写入文件；否则，每次写入文件时，其旧内容都会被覆盖。我相信您可以从 context 对象中获取文件路径。然后，您可以执行以下操作:

//Set true for append mode
BufferedWriter writer = new BufferedWriter(new FileWriter(your-file-path, true));  
writer.write(data);
writer.close();