earlier error on empty clipboard

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/EncryptDecryptOverviewFragment.java

@@ -37,6 +37,7 @@ import org.sufficientlysecure.keychain.R;
 import org.sufficientlysecure.keychain.compatibility.ClipboardReflection;
 import org.sufficientlysecure.keychain.pgp.PgpHelper;
 import org.sufficientlysecure.keychain.ui.util.Notify;
+import org.sufficientlysecure.keychain.ui.util.Notify.Style;
 import org.sufficientlysecure.keychain.ui.util.SubtleAttentionSeeker;
 import org.sufficientlysecure.keychain.util.FileHelper;
 
@@ -92,15 +93,30 @@ public class EncryptDecryptOverviewFragment extends Fragment {
         mDecryptFromClipboard.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
-                Intent clipboardDecrypt = new Intent(getActivity(), DecryptActivity.class);
-                clipboardDecrypt.setAction(DecryptActivity.ACTION_DECRYPT_FROM_CLIPBOARD);
-                startActivityForResult(clipboardDecrypt, 0);
+                decryptFromClipboard();
             }
         });
 
         return view;
     }
 
+    private void decryptFromClipboard() {
+
+        Activity activity = getActivity();
+        if (activity == null) {
+            return;
+        }
+
+        final CharSequence clipboardText = ClipboardReflection.getClipboardText(activity);
+        if (clipboardText == null) {
+            Notify.create(activity, R.string.error_clipboard_empty, Style.ERROR);
+        }
+
+        Intent clipboardDecrypt = new Intent(getActivity(), DecryptActivity.class);
+        clipboardDecrypt.setAction(DecryptActivity.ACTION_DECRYPT_FROM_CLIPBOARD);
+        startActivityForResult(clipboardDecrypt, 0);
+    }
+
     @Override
     public void onResume() {
         super.onResume();

OpenKeychain/src/main/res/values/strings.xml

@@ -1352,5 +1352,6 @@
     <string name="file_delete_ok">"Original file deleted."</string>
     <string name="file_delete_none">"No file deleted! (Already deleted?)"</string>
     <string name="file_delete_exception">"Original file could not be deleted!"</string>
+    <string name="error_clipboard_empty">"Clipboard is empty!"</string>
 
 </resources>