\n * Usually, LayoutManager does not need to worry about this. However, in some cases, your\n * LayoutManager may need to call some custom component with item positions in which\n * case you need the actual adapter position instead of the pre layout position. You\n * can use this method to convert a pre-layout position to adapter (post layout) position.\n *
\n * Note that if the provided position belongs to a deleted ViewHolder, this method will\n * return -1.\n *
\n * Calling this method in post-layout state returns the same value back.\n *\n * @param position The pre-layout position to convert. Must be greater or equal to 0 and\n * less than {@link State#getItemCount()}.\n */\n public int convertPreLayoutPositionToPostLayout(int position) {\n if (position < 0 || position >= mState.getItemCount()) {\n throw new IndexOutOfBoundsException(\"invalid position \" + position + \". State \"\n + \"item count is \" + mState.getItemCount() + exceptionLabel());\n }\n if (!mState.isPreLayout()) {\n return position;\n }\n return mAdapterHelper.findPositionOffset(position);\n }\n\n /**\n * Obtain a view initialized for the given position.\n *\n * This method should be used by {@link LayoutManager} implementations to obtain\n * views to represent data from an {@link Adapter}.\n *
\n * The Recycler may reuse a scrap or detached view from a shared pool if one is\n * available for the correct view type. If the adapter has not indicated that the\n * data at the given position has changed, the Recycler will attempt to hand back\n * a scrap view that was previously initialized for that data without rebinding.","sourceCodeStart":6089,"sourceCodeEnd":6125,"githubUrl":"https://github.com/DrKLO/Telegram/blob/45ab8f4308496e1f01026a97fcdb0d58a5274474/TMessagesProj/src/main/java/androidx/recyclerview/widget/RecyclerView.java#L6089-L6125","documentation":"Recycler.convertPreLayoutPositionToPostLayout throws IndexOutOfBoundsException ('invalid position') when the supplied position is outside [0, mState.getItemCount()). This method maps a pre-layout position to its post-layout adapter position; it requires the input to be a valid position in the current State's item count (which during pre-layout includes items pending removal). Passing a negative or >= itemCount position violates the precondition before the offset translation is even attempted.","triggerScenarios":"A LayoutManager computing pre-layout positions passing a stale or out-of-range index; calling this outside a layout pass with a position derived from a previous, now-invalid state; off-by-one where a position equal to getItemCount() is passed (must be < count).","commonSituations":"Custom LayoutManager caching positions across state resets; calling convertPreLayoutPositionToPostLayout during post-layout (where it returns the position unchanged but still validates bounds); adapter count shrunk between position capture and conversion call.","solutions":["Clamp/guard the input position: ensure 0 <= position < state.getItemCount() before calling; re-read count from the current State each time.","Do not cache positions across layout passes in a custom LayoutManager — derive them fresh from State each layout.","Ensure the call is only made during pre-layout (State.isPreLayout()); in post-layout the conversion is the identity and the bounds check still applies."],"exampleFix":"// before (custom LayoutManager)\nint postPos = recycler.convertPreLayoutPositionToPostLayout(cachedPos); // cachedPos stale\n// after\nint count = state.getItemCount();\nif (cachedPos >= 0 && cachedPos < count) {\n int postPos = recycler.convertPreLayoutPositionToPostLayout(cachedPos);\n} else {\n // position no longer valid; skip or recompute\n}","handlingStrategy":"validation","validationCode":"int count = state.getItemCount();\nif (position >= 0 && position < count) {\n int post = recycler.convertPreLayoutPositionToPostLayout(position);\n} else {\n // invalid; skip or recompute\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["In custom LayoutManagers, derive positions fresh from State each pass.","Only call convertPreLayoutPositionToPostLayout during pre-layout (State.isPreLayout()).","Never cache positions across state resets."],"tags":["recyclerview","layoutmanager","pre-layout","position-tracking"],"backgroundTag":null,"analyzedSha":"45ab8f4308496e1f01026a97fcdb0d58a5274474","analyzedAt":"2026-08-14T05:19:30.815Z","schemaVersion":2},"datasetVersion":"2026-08-14T10:17:34.591Z"}