splash-screen-switchToReactView.java

// MainActivity.java

public void switchToReactView() {
  if (mReactRootView != null && !mReactRootView.isAttachedToWindow()) {
    mReactRootView.setAlpha(0f);
    mReactRootView.animate()
        .alpha(1f)
        .setInterpolator(new AccelerateDecelerateInterpolator())
        .setDuration(350)
        .setListener(new Animator.AnimatorListener() {
          @Override
          public void onAnimationStart(Animator animation) {
            setContentView(mReactRootView);
          }

          @Override
          public void onAnimationEnd(Animator animation) {
            setTheme(R.style.AppTheme);
          }

          @Override
          public void onAnimationCancel(Animator animation) {

          }

          @Override
          public void onAnimationRepeat(Animator animation) {

          }
        })
        .start();
  }
}