fix some problems found by code analysis

app/src/main/java/com/nononsenseapps/notepad/activities/main/ActivityMain.java

@@ -198,7 +198,7 @@ public boolean onPrepareOptionsMenu(Menu menu) {
 	}
 
 	@Override
-	public boolean onOptionsItemSelected(MenuItem item) {
+	public boolean onOptionsItemSelected(@NonNull MenuItem item) {
 		// Pass the event to ActionBarDrawerToggle. If it returns true, then it has handled the
 		// drawer icon touch event
 		if (mDrawerToggle.onOptionsItemSelected(item)) {

app/src/main/java/com/nononsenseapps/notepad/android/provider/TextFileProvider.java

@@ -26,6 +26,8 @@
 import android.os.Environment;
 import android.util.Log;
 
+import androidx.annotation.NonNull;
+
 import com.nononsenseapps.notepad.BuildConfig;
 import com.nononsenseapps.notepad.providercontract.ProviderContract;
 
@@ -73,20 +75,20 @@ public TextFileProvider() {
 	}
 
 	@Override
-	public int delete(Uri uri, String selection, String[] selectionArgs) {
+	public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
 		// Implement this to handle requests to delete one or more rows.
 		throw new UnsupportedOperationException("Not yet implemented");
 	}
 
 	@Override
-	public String getType(Uri uri) {
+	public String getType(@NonNull Uri uri) {
 		// TODO: Implement this to handle requests for the MIME type of the data
 		// at the given URI.
 		throw new UnsupportedOperationException("Not yet implemented");
 	}
 
 	@Override
-	public Uri insert(Uri uri, ContentValues values) {
+	public Uri insert(@NonNull Uri uri, ContentValues values) {
 		// TODO: Implement this to handle requests to insert a new row.
 		throw new UnsupportedOperationException("Not yet implemented");
 	}
@@ -154,7 +156,7 @@ public Cursor query(Uri uri, String[] projection, String selection,
 	}
 
 	@Override
-	public int update(Uri uri, ContentValues values, String selection,
+	public int update(@NonNull Uri uri, ContentValues values, String selection,
 					  String[] selectionArgs) {
 		// TODO: Implement this to handle requests to update one or more rows.
 		throw new UnsupportedOperationException("Not yet implemented");

app/src/main/java/com/nononsenseapps/notepad/database/MyContentProvider.java

@@ -28,6 +28,8 @@
 import android.database.sqlite.SQLiteStatement;
 import android.net.Uri;
 
+import androidx.annotation.NonNull;
+
 import com.nononsenseapps.helpers.NnnLogger;
 import com.nononsenseapps.helpers.UpdateNotifier;
 import com.nononsenseapps.notepad.BuildConfig;
@@ -59,7 +61,7 @@ public MyContentProvider() {
 	}
 
 	@Override
-	public String getType(Uri uri) {
+	public String getType(@NonNull Uri uri) {
 		switch (sURIMatcher.match(uri)) {
 			case Notification.BASEITEMCODE:
 			case Notification.BASEURICODE:
@@ -108,7 +110,7 @@ public boolean onCreate() {
 	}
 
 	@Override
-	synchronized public Uri insert(Uri uri, ContentValues values) {
+	synchronized public Uri insert(@NonNull Uri uri, ContentValues values) {
 		final SQLiteDatabase db = DatabaseHandler.getInstance(getContext())
 				.getWritableDatabase();
 
@@ -159,7 +161,7 @@ synchronized public Uri insert(Uri uri, ContentValues values) {
 	}
 
 	@Override
-	synchronized public int update(Uri uri, ContentValues values,
+	synchronized public int update(@NonNull Uri uri, ContentValues values,
 								   String selection, String[] selectionArgs) {
 		final SQLiteDatabase db = DatabaseHandler.getInstance(getContext())
 				.getWritableDatabase();
@@ -299,7 +301,7 @@ synchronized private int safeDeleteItem(final SQLiteDatabase db,
 	}
 
 	@Override
-	synchronized public int delete(Uri uri, String selection,
+	synchronized public int delete(@NonNull Uri uri, String selection,
 								   String[] selectionArgs) {
 		final SQLiteDatabase db = DatabaseHandler.getInstance(getContext())
 				.getWritableDatabase();
@@ -368,7 +370,7 @@ synchronized public int delete(Uri uri, String selection,
 	}
 
 	@Override
-	synchronized public Cursor query(Uri uri, String[] projection, String selection,
+	synchronized public Cursor query(@NonNull Uri uri, String[] projection, String selection,
 									 String[] selectionArgs, String sortOrder) {
 		Cursor result;
 		final long id;

app/src/main/java/com/nononsenseapps/notepad/prefs/PasswordPrefs.java

@@ -72,7 +72,7 @@ private void applyPassword() {
 					.getDefaultSharedPreferences(this.getContext());
 			String currentPassword = settings.getString(KEY_PASSWORD, "");
 
-			if ("".equals(currentPassword)) {
+			if (currentPassword.isEmpty()) {
 				// it's new => Save the password directly
 				settings.edit()
 						.putString(KEY_PASSWORD, passw1)
@@ -100,7 +100,7 @@ private void clearPassword() {
 				.getDefaultSharedPreferences(this.getContext());
 		String currentPassword = settings.getString(KEY_PASSWORD, "");
 
-		if ("".equals(currentPassword)) {
+		if (currentPassword.isEmpty()) {
 			// Save the (empty) password directly
 			settings.edit()
 					.putString(KEY_PASSWORD, "")

app/src/main/java/com/nononsenseapps/notepad/sync/orgsync/OrgProvider.java

@@ -143,7 +143,7 @@ public boolean onCreate() {
 	}
 
 	@Override
-	public Cursor query(Uri uri, String[] projection, String selection,
+	public Cursor query(@NonNull Uri uri, String[] projection, String selection,
 						String[] selectionArgs, String sortOrder) {
 		if (!PreferencesHelper.isSdSyncEnabled(getContext())) {
 			return null;
@@ -168,12 +168,12 @@ public Cursor query(Uri uri, String[] projection, String selection,
 	}
 
 	@Override
-	public String getType(Uri uri) {
+	public String getType(@NonNull Uri uri) {
 		throw new UnsupportedOperationException("Not yet implemented");
 	}
 
 	@Override
-	public Uri insert(Uri uri, ContentValues values) {
+	public Uri insert(@NonNull Uri uri, ContentValues values) {
 		if (!PreferencesHelper.isSdSyncEnabled(getContext())) {
 			return null;
 		}
@@ -207,7 +207,7 @@ public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
 	}
 
 	@Override
-	public int update(Uri uri, ContentValues values, String selection,
+	public int update(@NonNull Uri uri, ContentValues values, String selection,
 					  String[] selectionArgs) {
 		if (!PreferencesHelper.isSdSyncEnabled(getContext())) {
 			return -1;

app/src/main/java/com/nononsenseapps/notepad/sync/orgsync/OrgSyncService.java

@@ -29,6 +29,7 @@
 import android.os.Message;
 import android.os.Process;
 
+import androidx.annotation.NonNull;
 import androidx.preference.PreferenceManager;
 
 import com.nononsenseapps.helpers.NnnLogger;
@@ -192,7 +193,7 @@ public void onMonitorChange() {
 		}
 
 		@Override
-		public void handleMessage(Message msg) {
+		public void handleMessage(@NonNull Message msg) {
 
 			if (synchronizers.isEmpty()) {
 				synchronizers.addAll(getSynchronizers());

app/src/main/java/com/nononsenseapps/ui/DateView.java

@@ -28,6 +28,7 @@
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.Date;
+import java.util.Locale;
 import java.util.TimeZone;
 
 /**
@@ -48,7 +49,6 @@ public DateView(Context context) {
 		// TODO if you want to also show a "due time" on the note, use this instead:
 		//  mDateFormatter = TimeFormatter.getLocalFormatterShort(context);
 		//  as of now we only show the date, which for me is good enough.
-		//  (note that this line is called many times in this file)
 		mDateFormatter = TimeFormatter.getLocalFormatterShortDateOnly(context);
 	}
 
@@ -58,8 +58,8 @@ public DateView(Context context, AttributeSet attrs) {
 		try {
 			mDateFormatter = TimeFormatter.getLocalFormatterShortDateOnly(context);
 		} catch (Exception e) {
-			// Just to function in view
-			mDateFormatter = new SimpleDateFormat();
+			// return a simple fallback formatter, just to show something in the view
+			mDateFormatter = new SimpleDateFormat("E d MMM yyyy, HH:ss", Locale.US);
 		}
 	}