findParentStackControllerForChildId

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/Navigator.java

 	}
 
 	public void push(final String fromId, final ViewController viewController) {
-		ViewController found = findControllerById(fromId);
-		if (found == null) return;
-
-		StackController parentStackController = found.getParentStackController();
-		if (parentStackController == null) return;
-
-		parentStackController.push(viewController);
+		StackController parentStackController = findParentStackControllerForChildId(fromId);
+		if (parentStackController != null) {
+			parentStackController.push(viewController);
+		}
 	}
 
 	public void pop(final String fromId) {
-		ViewController found = findControllerById(fromId);
-		if (found == null) return;
-
-		StackController parentStackController = found.getParentStackController();
-		if (parentStackController == null) return;
-
-		parentStackController.pop();
+		StackController parentStackController = findParentStackControllerForChildId(fromId);
+		if (parentStackController != null) {
+			parentStackController.pop();
+		}
 	}
 }

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/ParentController.java

 
 import android.app.Activity;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
 
 	public abstract Collection<ViewController> getChildControllers();
 
+	@Nullable
 	public ViewController findControllerById(final String id) {
 		ViewController fromSuper = super.findControllerById(id);
 		if (fromSuper != null) {
 
 		return null;
 	}
+
+	@Nullable
+	public StackController findParentStackControllerForChildId(final String childId) {
+		ViewController found = findControllerById(childId);
+		return found != null ? found.getParentStackController() : null;
+	}
 }

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/ParentControllerTest.java

 		assertThat(uut.findControllerById("child1")).isEqualTo(child1);
 		assertThat(uut.findControllerById("child2")).isEqualTo(child2);
 	}
+
+	@Test
+	public void findParentStackControllerForChildId() throws Exception {
+		ViewController child1 = new SimpleViewController(activity, "child1");
+		ViewController child2 = new SimpleViewController(activity, "child2");
+
+		final StackController someInnerStack = new StackController(activity, "stack1");
+		someInnerStack.push(child1);
+		someInnerStack.push(child2);
+
+		ParentController uut = new ParentController(activity, "uut") {
+			@Override
+			public Collection<ViewController> getChildControllers() {
+				return Arrays.<ViewController>asList(someInnerStack);
+			}
+
+			@NonNull
+			@Override
+			protected View createView() {
+				return new FrameLayout(activity);
+			}
+		};
+
+		assertThat(uut.findParentStackControllerForChildId("not existing child")).isNull();
+		assertThat(uut.findParentStackControllerForChildId("child2")).isEqualTo(someInnerStack);
+	}
 }