public void set(int n, Item item) {
    if (item == null) {
      throw new NullPointerException("item == null");
    }

    set0(n, item);
  }
Sets the item at the given index.

@param n {@code >= 0, < size();} which element
@param item {@code non-null;} the item
android/android_framework/dex-maker/src/main/java/com/android/dx/cf/code/LineNumberList.java