Code cleanup for show method

Concerns are now more separated for the SplashScreen#show methods.

Author: christophermark

README.md

@@ -233,7 +233,7 @@ Create a style definition for this in `android/app/src/main/res/values/colors.xm
 
 Change your `show` method to include your custom style:
 ```java
-SplashScreen.show(this, false, R.style.SplashScreenTheme);
+SplashScreen.show(this, R.style.SplashScreenTheme);
 ```
 
 ### iOS    

android/src/main/java/org/devio/rn/splashscreen/SplashScreen.java

@@ -14,27 +14,20 @@
  * Email:crazycodeboy@gmail.com
  */
 public class SplashScreen {
-    private static int NULL_ID = 0;
     private static Dialog mSplashDialog;
     private static WeakReference<Activity> mActivity;
 
     /**
      * 打开启动屏
      */
-    public static void show(final Activity activity, final boolean fullScreen, final int themeResId) {
+    public static void show(final Activity activity, final int themeResId) {
         if (activity == null) return;
         mActivity = new WeakReference<Activity>(activity);
         activity.runOnUiThread(new Runnable() {
             @Override
             public void run() {
                 if (!activity.isFinishing()) {
-
-                    mSplashDialog = new Dialog(
-                            activity,
-                            themeResId != NULL_ID ? themeResId
-                                    : fullScreen ? R.style.SplashScreen_Fullscreen
-                                    : R.style.SplashScreen_SplashTheme
-                    );
+                    mSplashDialog = new Dialog(activity, themeResId);
                     mSplashDialog.setContentView(R.layout.launch_screen);
                     mSplashDialog.setCancelable(false);
 
@@ -50,7 +43,9 @@ public void run() {
      * 打开启动屏
      */
     public static void show(final Activity activity, final boolean fullScreen) {
-        show(activity, fullScreen, 0);
+        int resourceId = fullScreen ? R.style.SplashScreen_Fullscreen : R.style.SplashScreen_SplashTheme;
+
+        show(activity, resourceId);
     }
 
     /**