adding a constant for empty layout ids

Author: HarshEvilGeek

demo/src/main/java/com/daimajia/swipedemo/MyActivity.java

@@ -30,7 +30,7 @@ protected void onCreate(Bundle savedInstanceState) {
         sample1.setShowMode(SwipeLayout.ShowMode.LayDown);
         sample1.setDragEdges(SwipeLayout.DragEdge.Left, SwipeLayout.DragEdge.Right, SwipeLayout.DragEdge.Top);
         // When using multiple drag edges it's a good idea to pass the ids of the views that you're using for the left, right, top bottom views (-1 if you're not using a particular view)
-        sample1.setBottomViewIds(R.id.bottom_wrapper, R.id.bottom_wrapper_2, R.id.starbott, -1);
+        sample1.setBottomViewIds(R.id.bottom_wrapper, R.id.bottom_wrapper_2, R.id.starbott, SwipeLayout.EMPTY_LAYOUT);
         sample1.addRevealListener(R.id.delete, new SwipeLayout.OnRevealListener() {
             @Override
             public void onReveal(View child, SwipeLayout.DragEdge edge, float fraction, int distance) {

library/src/main/java/com/daimajia/swipe/SwipeLayout.java

@@ -25,6 +25,8 @@
 
 public class SwipeLayout extends FrameLayout {
 
+    public static final int EMPTY_LAYOUT = -1;
+
     private static final int DRAG_LEFT = 1;
     private static final int DRAG_RIGHT = 2;
     private static final int DRAG_TOP = 4;
@@ -1161,31 +1163,31 @@ public List<ViewGroup> getBottomViews() {
     // Pass the id of the view if set, otherwise pass -1
     public void setBottomViewIds(int left, int right, int top, int bottom) {
         if (mDragEdges.contains(DragEdge.Left)) {
-            if (left == -1) {
+            if (left == EMPTY_LAYOUT) {
                 mBottomViewIdsSet = false;
             } else {
                 mBottomViewIdMap.put(DragEdge.Left, left);
                 mBottomViewIdsSet = true;
             }
         }
         if (mDragEdges.contains(DragEdge.Right)) {
-            if (right == -1) {
+            if (right == EMPTY_LAYOUT) {
                 mBottomViewIdsSet = false;
             } else {
                 mBottomViewIdMap.put(DragEdge.Right, right);
                 mBottomViewIdsSet = true;
             }
         }
         if (mDragEdges.contains(DragEdge.Top)) {
-            if (top == -1) {
+            if (top == EMPTY_LAYOUT) {
                 mBottomViewIdsSet = false;
             } else {
                 mBottomViewIdMap.put(DragEdge.Top, top);
                 mBottomViewIdsSet = true;
             }
         }
         if (mDragEdges.contains(DragEdge.Bottom)) {
-            if (bottom == -1) {
+            if (bottom == EMPTY_LAYOUT) {
                 mBottomViewIdsSet = false;
             } else {
                 mBottomViewIdMap.put(DragEdge.Bottom, bottom);