创建新的java.io.File（）用于FileDataStoreFactory（DIR）一个新的目录

Question

My MainActivity looks like the following:

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       Button b = (Button) findViewById(R.id.button);
       b.setOnClickListener(new View.OnClickListener() {
           @Override
            public void onClick(View v) {
                CalManager c = new CalManager(MainActivity.this);
                try{c.addEvent();}
                catch(IOException e){
                   Log.d("mychecks", "failed");
                }
            }
        });
    }
}

Furthermore, my xml is the following:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.user.test">
    <uses-permission android:name="android.permission.WRITE_CALENDAR"/>
    <uses-permission 
      android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

And I've got a problem with the following code in the CalManager-class:

public class CalManager {
    Context ctx;
    String dir;

    public CalManager(Context c){
        this.ctx = c;
        dir = ctx.getFilesDir().toString();
    }

    /** Directory to store user credentials for this application. */
    private static final java.io.File DATA_STORE_DIR = new java.io.File(
            dir , ".credentials/test");

    /** Global instance of the {@link FileDataStoreFactory}. */
    private static FileDataStoreFactory DATA_STORE_FACTORY;

    static {
        try {
            DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }

    ...
}

The

DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);

Statement throws the following error:

11-10 09:26:22.939 2374-2374/com.example.user.test W/System.err: java.io.IOException: unable to create directory: /.credentials/test

any ideas on how to fix this?

Thanks in advance!

Answer 1

Creating a new directory with new java.io.File()

Stop right there. Instantiating a File doesn't create a file on disk.

You need DATA_STORE_DIR.mkdirs() somewhere.

But you have another problem. dir is an instance member initialized but he constructor, so you can't use it in static code. You wil have to remove static from this File and the anonymous initializer block.