java.lang.IllegalStateException: Fragment already added about androidbox HOT 2 OPEN

 public void addFragment(Fragment fragment, boolean moveToStateNow) {
        if (DEBUG) Log.v(TAG, "add: " + fragment);
        makeActive(fragment);
        if (!fragment.mDetached) {
            if (mAdded.contains(fragment)) {
                throw new IllegalStateException("Fragment already added: " + fragment);
            }
            synchronized (mAdded) {
                mAdded.add(fragment);
            }
            fragment.mAdded = true;
            fragment.mRemoving = false;
            if (fragment.mView == null) {
                fragment.mHiddenChanged = false;
            }
            if (fragment.mHasMenu && fragment.mMenuVisible) {
                mNeedMenuInvalidate = true;
            }
            if (moveToStateNow) {
                moveToState(fragment);
            }
        }
    }

 FragmentManager manager = getSupportFragmentManager();
 FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.content, toFragment, fragmentTag);
transaction.commitAllowingStateLoss();

    @Override
    public FragmentTransaction add(int containerViewId, Fragment fragment, String tag) {
        doAddOp(containerViewId, fragment, tag, OP_ADD);
        return this;
    }

 void executeOps() {
        final int numOps = mOps.size();
        for (int opNum = 0; opNum < numOps; opNum++) {
            final Op op = mOps.get(opNum);
            final Fragment f = op.fragment;
            if (f != null) {
                f.setNextTransition(mTransition, mTransitionStyle);
            }
            switch (op.cmd) {
                case OP_ADD:
                    f.setNextAnim(op.enterAnim);
                    mManager.addFragment(f, false);
                    break;
                case OP_REMOVE:
                    f.setNextAnim(op.exitAnim);
                    mManager.removeFragment(f);
                    break;
                case OP_HIDE:
                    f.setNextAnim(op.exitAnim);
                    mManager.hideFragment(f);
                    break;
                case OP_SHOW:
                    f.setNextAnim(op.enterAnim);
                    mManager.showFragment(f);
                    break;
                case OP_DETACH:
                    f.setNextAnim(op.exitAnim);
                    mManager.detachFragment(f);
                    break;
                case OP_ATTACH:
                    f.setNextAnim(op.enterAnim);
                    mManager.attachFragment(f);
                    break;
                case OP_SET_PRIMARY_NAV:
                    mManager.setPrimaryNavigationFragment(f);
                    break;
                case OP_UNSET_PRIMARY_NAV:
                    mManager.setPrimaryNavigationFragment(null);
                    break;
                default:
                    throw new IllegalArgumentException("Unknown cmd: " + op.cmd);
            }
            if (!mReorderingAllowed && op.cmd != OP_ADD && f != null) {
                mManager.moveFragmentToExpectedState(f);
            }
        }
        if (!mReorderingAllowed) {
            // Added fragments are added at the end to comply with prior behavior.
            mManager.moveToState(mManager.mCurState, true);
        }
    }

 FragmentActivity hostFragment = toFragment.getActivity();
        if (null == hostFragment || this != hostFragment) {
            LogUtil.i("add fragment：" + fragmentTag);
            // 判断如果已经添加则先remove掉
            if (toFragment.isAdded()) {
                LogUtil.w(TAG, "remove first : " + toFragment);
                transaction.remove(toFragment);
            }
            transaction.add(R.id.content, toFragment, fragmentTag);
        }