android - 为什么这个 Android FileOutputStream 会抛出 NullPointerException？

Question

似乎没有需要为文件io设置任何Android list 权限。

public class Device extends Activity {
    private static final Configuration config = new Configuration();
    ...
    private boolean applyMenuChoice(MenuItem item) {
        switch (item.getItemId()) {
        ...
        case R.id.menuSave:
            ...
            configuration.modify(name, to, from, user);
            configuration.write();
            ...

public class Configuration extends Activity {
    private final static String CONFIG = "config.txt";
    private static StringBuilder config = new StringBuilder();
    ...
    public void write() {
        try {
            FileOutputStream fos = openFileOutput(CONFIG, Context.MODE_PRIVATE);
            fos.write(config.toString().getBytes());
            ...

Answer 1

用正确的方法替换 Activity 的非法实例化解决了这个问题。非常感谢(再次)Falmarri。