IOException为get消息返回null

Question

try {
    fis = context.openFileInput("Stores");
    ObjectInputStream oi = new ObjectInputStream(fis);
    toReturn = (ArrayList<Store>) oi.readObject();
    oi.close();
} catch (FileNotFoundException e) {
    Log.e("InternalStorage", e.getMessage());
} catch (IOException e) {
    Log.e("InternalStorage", e.getMessage());
} catch (ClassNotFoundException e) {
    e.printStackTrace();
}

我在IOException范围内有一个崩溃日志，说

java.lang.NullPointerException: println needs a message

为什么会发生这种情况？

Answer 1

因为在调用e.getMessage（）时IOException总是返回null。 发生此异常时，请尝试记录其他内容。

例如：

    StackTraceElement[] stackTraceElements = e2.getStackTrace();
    String logMessage = "IOException occured in method "
            + stackTraceElements[0].getMethodName() + " - File name is "
            + stackTraceElements[0].getFileName()
            + " - At line number: "
            + stackTraceElements[0].getLineNumber();
    Log.e("InternalStorage", e.getMessage());