Fix fingerprint not restored permanently (closes #26)

Author: divadsn

app/src/main/java/de/codebucket/mkkm/MobileKKM.java

@@ -93,6 +93,11 @@ public String getFingerprint() {
         return UUID.nameUUIDFromBytes(deviceId.getBytes()).toString().replaceAll("-", "");
     }
 
+    public void updateFingerprint(String fingerprint) {
+        preferences.edit().putString("fingerprint", fingerprint).apply();
+        loginHelper.updateFingerprint(fingerprint);
+    }
+
     public boolean isNetworkConnectivity() {
         ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
         if (cm != null) {

app/src/main/java/de/codebucket/mkkm/activity/BackupActivity.java

@@ -166,7 +166,7 @@ private void doRestore(Uri uri) {
 
                 // Check if associated account is currently logged in
                 if (AccountUtils.getPassengerId(AccountUtils.getAccount()).equals(account)) {
-                    MobileKKM.getLoginHelper().updateFingerprint(fingerprint);
+                    MobileKKM.getInstance().updateFingerprint(fingerprint);
                     Toast.makeText(this, R.string.backup_import_success, Toast.LENGTH_SHORT).show();
                 } else {
                     Toast.makeText(this, R.string.backup_wrong_account, Toast.LENGTH_SHORT).show();
@@ -246,7 +246,7 @@ public void onClick(DialogInterface dialog, int which) {
                             return;
                         }
 
-                        MobileKKM.getLoginHelper().updateFingerprint(fingerprint);
+                        MobileKKM.getInstance().updateFingerprint(fingerprint);
                         Toast.makeText(BackupActivity.this, R.string.backup_import_success, Toast.LENGTH_SHORT).show();
                     }
                 })