如何使用getExternalStorageDirectory（）从外部存储读取子目录

Question

I am developing an Android app that should read Files from the External Storage and display them in a Listview; creating the subdirectory on the External Storage works fine. The problem is reading from the Subdirectory of the External Storage and I still haven´t figured out how to solve this problem. The Listview displays all the subdirectories of the External Storage and I just want to display the content in one particular subdirectory. The problem consists in "casting" a String into a File Object, which is obviously not possible. Do I really need to open a FileInputStream for that? Any help or hints would be very much appreciated.

I tried to attach the subdirectory as a string to the Environment.getExternalStorageDirectory() method, lik this: Environment.getExternalStorageDirectory() + "/Audio";

mTextMessage = findViewById(R.id.message);
BottomNavigationView navigation = findViewById(R.id.navigation); 
navigation.setOnNavigationItemSelectedListener
(mOnNavigationItemSelectedListener);
mListView = (ListView) findViewById(R.id.listView1);
file = Environment.getExternalStorageDirectory() + "/Audio";
fileNameList = getFileListfromSDCard();
mAdapter = new FlAdapter(this, R.layout.fl_list_item, fileNameList);
mListView.setAdapter(mAdapter);

The error message:

error: incompatible types: String cannot be converted to File

Answer 1

Because getExternalStorageDirectory() returns String , you need to convert it to file before assigning it to file. You can try like this.

File file = new File(Environment.getExternalStorageDirectory()+"/Audio");