* [Android] Fix NPE in integer convert. (#2427)

Author: YorkShen

android/sdk/src/main/java/com/taobao/weex/utils/WXUtils.java

@@ -245,7 +245,7 @@ public static int getInt(Object value) {
     return getInteger(value, 0);
   }
 
-  public static Integer getInteger(@Nullable Object value, @Nullable Integer df) {
+  public static @Nullable Integer getInteger(@Nullable Object value, @Nullable Integer df) {
 
     if (value == null) {
       return df;
@@ -308,7 +308,7 @@ public static Integer getInteger(@Nullable Object value, @Nullable Integer df) {
           WXLogUtils.e("Argument error! value is " + value, e);
         }
       }
-      if (!ret.equals(df)) {
+      if (ret != null && !ret.equals(df)) {
         sCache.put(key, ret);
       }
       return ret;