diff --git a/android/app/src/main/java/com/dinect/checker/AbstractScannerActivity.java b/android/app/src/main/java/com/dinect/checker/AbstractScannerActivity.java
index e3a97fe..581e212 100644
--- a/android/app/src/main/java/com/dinect/checker/AbstractScannerActivity.java
+++ b/android/app/src/main/java/com/dinect/checker/AbstractScannerActivity.java
@@ -23,6 +23,7 @@ import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
+import android.os.Handler;
 import android.support.annotation.NonNull;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.AppCompatActivity;
@@ -39,6 +40,8 @@ import android.widget.Toast;
 
 import com.dinect.net.ApiClient;
 
+import java.util.Queue;
+import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.atomic.AtomicInteger;
 
 
@@ -62,11 +65,12 @@ public abstract class AbstractScannerActivity extends AppCompatActivity {
     public static final String ERROR_INFO = "ERROR_INFO";
 
 
+    protected AppCompatActivity ctx;
     protected ApiClient apiClient;
     protected NetworkThread networkThread;
-    private DecrementCounterThread counterThread;
-
-    LogoutDialogFragment logoutDialog;
+    protected DecrementCounterThread counterThread;
+    protected LogoutDialogFragment logoutDialog;
+    protected NotificationThread notificationThread;
 
     boolean isCameraAvailable() {
         Log.d(TAG, "isCameraAvailable");
@@ -79,6 +83,7 @@ public abstract class AbstractScannerActivity extends AppCompatActivity {
         final Intent response = new Intent();
         response.putExtra(ERROR_INFO, message);
         setResult(RESULT_CANCELED, response);
+        notificationThread = null;
     }
 
     /**
@@ -95,10 +100,12 @@ public abstract class AbstractScannerActivity extends AppCompatActivity {
             cancelRequest("Camera unavailable");
             return false;
         }
+        ctx = this;
+        notificationThread = new NotificationThread(this);
+        notificationThread.start();
         // Hide the window title.
         requestWindowFeature(Window.FEATURE_NO_TITLE);
         setContentView(layoutID);
-
         return true;
     }
 
@@ -142,21 +149,22 @@ public abstract class AbstractScannerActivity extends AppCompatActivity {
                         toastMessage = CLICK_MESSAGES[2];
                         break;
                     case 23:
-                        toastMessage = CLICK_MESSAGES[3];
+                        toastMessage = null;
                         counterThread.pause();
-                        counter.set(0);
+                        Toast.makeText(ctx, CLICK_MESSAGES[3], Toast.LENGTH_SHORT).show();
                         switchScanner();
                         break;
                 }
                 Log.d(TAG, "toolbar clicked " + counter.get() + " times");
 
                 if (null != toastMessage) {
-                    Toast.makeText(getApplicationContext(), toastMessage, Toast.LENGTH_SHORT).show();
+                    notificationThread.addMessage(toastMessage);
                 }
             }
         });
     }
 
+
     private class DecrementCounterThread extends Thread {
         final long delay;
         final AtomicInteger counter;
@@ -255,7 +263,7 @@ public abstract class AbstractScannerActivity extends AppCompatActivity {
      */
     public void handleBarcode(final @NonNull String card) {
         Log.d(TAG, "handleBarcode");
-        Toast.makeText(this, card, Toast.LENGTH_SHORT).show();
+        notificationThread.addMessage(card);
         networkThread = new NetworkThread(this, apiClient);
         networkThread.card(card).start();
     }
@@ -268,11 +276,12 @@ public abstract class AbstractScannerActivity extends AppCompatActivity {
             intent.putExtra("user", result.second);
             intent.putExtra("card", result.first);
             setResult(RESULT_OK, intent);
-            networkThread.close();
+            networkThread.cancel();
+            notificationThread.cancel();
             finish();
         } else {
             if (null != result.second) {
-                Toast.makeText(this, result.second, Toast.LENGTH_SHORT).show();
+                notificationThread.addMessage(result.second);
             }
         }
     }
@@ -341,4 +350,54 @@ public abstract class AbstractScannerActivity extends AppCompatActivity {
             return builder.create();
         }
     }
+
+    private class NotificationThread extends Thread {
+
+        private final static int MAX_NOTIFICATION_MESSAGES = 2;
+
+        private boolean run = true;
+        private final Queue<String> queue;
+        private final AbstractScannerActivity ctx;
+
+        public NotificationThread(final @NonNull AbstractScannerActivity ctx) {
+            this.queue = new ArrayBlockingQueue<>(MAX_NOTIFICATION_MESSAGES);
+            this.ctx = ctx;
+        }
+
+        @Override
+        public void run() {
+            while (run) {
+                if (null != queue.peek()) {
+                    Log.d(TAG, "null != queue.peek()");
+                    final String message = queue.poll();
+                    Log.d(TAG, "message: " + message);
+                    if (null != message) {
+                        runOnUiThread(new Runnable() {
+                            @Override
+                            public void run() {
+                                Toast.makeText(ctx, message, Toast.LENGTH_SHORT).show();
+                            }
+                        });
+                    }
+                }
+                try {
+                    Thread.sleep(300);
+                } catch (final InterruptedException ie) {
+                    run = false;
+                }
+            }
+        }
+
+        public void addMessage(final @NonNull String message) {
+            if (queue.size() == MAX_NOTIFICATION_MESSAGES) {
+                Log.d(TAG, "Discard message: " + queue.poll());
+            }
+            queue.add(message);
+            Log.d(TAG, "Add message: " + message);
+        }
+
+        public void cancel() {
+            run = false;
+        }
+    }
 }
diff --git a/android/app/src/main/java/com/dinect/checker/NetworkThread.java b/android/app/src/main/java/com/dinect/checker/NetworkThread.java
index 6bc7c1e..40f70a0 100644
--- a/android/app/src/main/java/com/dinect/checker/NetworkThread.java
+++ b/android/app/src/main/java/com/dinect/checker/NetworkThread.java
@@ -66,7 +66,7 @@ public final class NetworkThread extends Thread {
         return this;
     }
 
-    void close() {
+    void cancel() {
         activity = null;
     }
 }
diff --git a/android/app/src/main/java/com/dinect/checker/zxing/ScannerActivity.java b/android/app/src/main/java/com/dinect/checker/zxing/ScannerActivity.java
index 7c98384..180a388 100644
--- a/android/app/src/main/java/com/dinect/checker/zxing/ScannerActivity.java
+++ b/android/app/src/main/java/com/dinect/checker/zxing/ScannerActivity.java
@@ -15,10 +15,8 @@
  */
 package com.dinect.checker.zxing;
 
-import android.content.Intent;
 import android.os.Bundle;
 import android.os.Handler;
-import android.support.annotation.NonNull;
 import android.view.View;
 
 import com.dinect.checker.AbstractScannerActivity;
@@ -33,6 +31,8 @@ import me.dm7.barcodescanner.zxing.ZXingScannerView;
 public class ScannerActivity extends AbstractScannerActivity
         implements ZXingScannerView.ResultHandler {
 
+    private static final int SCAN_INTERVAL_PERIOD = 2000;
+
     private ZXingScannerView scannerView;
 
     @Override
@@ -84,6 +84,6 @@ public class ScannerActivity extends AbstractScannerActivity
             public void run() {
                 scannerView.resumeCameraPreview(ScannerActivity.this);
             }
-        }, 500);
+        }, SCAN_INTERVAL_PERIOD);
     }
 }