Java FileInputStream在android小部件中不工作

我最近发现，由于某种原因，我无法在android小部件上使用FileInputStream。不幸的是，我没能找到解决办法。 每次我尝试，我都会得到

无法解析方法“openFileInput”（java.lang.string）

你能帮我吗

try {
        FileInputStream HomeWorkIN = openFileInput(Class + ".txt");
        InputStreamReader HomeWorkREAD = new InputStreamReader(HomeWorkIN);
        char[] data = new char[ReadingBlock];
        String FinalData = "";
        int Size;
        try {
            while ((Size = HomeWorkREAD.read(data)) > 0) {
                String ReadData = String.copyValueOf(data, 0, Size);
                FinalData += ReadData;
                data = new char[ReadingBlock];
            }
            HomeWork += FinalData;
        } catch (IOException e) {
            e.printStackTrace();
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }

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使用context.openFileInput

FileInputStream HomeWorkIN = context.openFileInput(Class + ".txt");