Double back press implemented.

Author: free4murad

source-code/app/src/main/java/org/buildmlearn/toolkit/activity/HomeActivity.java

@@ -5,9 +5,11 @@
 import android.app.FragmentTransaction;
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Handler;
 import android.support.v4.widget.DrawerLayout;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
+import android.widget.Toast;
 
 import org.buildmlearn.toolkit.R;
 import org.buildmlearn.toolkit.constant.Constants;
@@ -25,6 +27,8 @@ public class HomeActivity extends AppCompatActivity
 
     private Section currentSection;
     private NavigationDrawerFragment mNavigationDrawerFragment;
+    private  boolean atHome = true;
+    private boolean backPressedOnce = false;
 
     /**
      * {@inheritDoc}
@@ -130,9 +134,24 @@ public void onBackPressed() {
             mNavigationDrawerFragment.closeDrawer();
             return;
         }
-        if (getFragmentManager().getBackStackEntryCount() <= 1) {
-            finish();
+        if(atHome){
+            if(backPressedOnce){
+                finish();
+            }
+            backPressedOnce=true;
+            Toast.makeText(this, "Tap back once more to exit.", Toast.LENGTH_SHORT).show();
+            new Handler().postDelayed(new Runnable()
+            {
+                @Override
+                public void run()
+                {
+                    backPressedOnce= false;
+                }
+            }, 2000);
+        }
+        else if(!atHome){
+            onNavigationDrawerItemSelected(0);
+            atHome = true;
         }
-        super.onBackPressed();
     }
 }