public int getFirst() {
        if (mHead == mTail) throw new ArrayIndexOutOfBoundsException();
        return mElements[mHead];
    }
Get first integer of the CircularIntArray.

@return The first integer.
@throws {@link ArrayIndexOutOfBoundsException} if CircularIntArray is empty.
android/android_framework/base/src/main/java/github/tornaco/android/thanos/core/util/collection/CircularIntArray.java