Android 文件不存在（但同时存在！）

Question

I have an Android program that creates a file and checks for it in an if statement. The purpose of this is to be able to save values in the app. The app works like this. I put the values in on the phone and I crash the app to reset it. The values were saved on the file. When I open the app again, it's supposed to skip the screen that lets me input the values. When I do this, the app acts as if the file never existed. Upon debug, I found that the file was indeed created. It should've been created on internal storage, but I also added the permission for external storage writing just in case. Can someone help me or give me an alternative please?

File file = new File("user.txt");
    if (file.exists())
    {
        ...
    }

Answer 1

        File f = new File(); 

it just create a file instance of file in runtime. You need to use following code to create a file.

        File file = new File("data/data/your package name/test.txt");
        if (!file.exists()) {
                try {
                    file.createNewFile();
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }

Answer 2

尝试给它一个完整的路径，而不仅仅是文件名，就像这样

File mFile = new File("/sdcard/mysdfile.txt");

Answer 3

The assets folder is read only at runtime.

From http://developer.android.com/guide/topics/data/data-storage.html#filesInternal

Tip: If you want to save a static file in your application at compile time, save the file in your project res/raw/ directory. You can open it with openRawResource(), passing the R.raw. resource ID. This method returns an InputStream that you can use to read the file (but you cannot write to the original file).

Take a look at using SharedPreferences for saving primitive data types.

Answer 4

        Boolean isSDPresent = android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);

                File direct = new File(Environment.getExternalStorageDirectory() + "/Folder/Filename");
                if (!direct.exists()) {
                    direct.mkdir(); // directory is created;
                }
                if (isSDPresent) {
                    Path = Environment.getExternalStorageDirectory() + "/Folder/Filename";

                } else {
                    Path = getFilesDir() + "/Folder/Filename";
                }
        File f = new File(Path);
      if(!file.exists()) {
       try {
                        file.createNewFile();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
}