lingochamp/FileDownloader · error · NoFieldException

getFileName

Error message

getFileName

What it means

This is not a system error but a sentinel guard: the MessageSnapshot subclass backing this object simply does not carry a filename field, so any call to getFileName() throws NoFieldException. It fires when code asks a sparse snapshot (e.g. a pending/connected/progress snapshot created without file metadata) for a field it never stored; the fault lies with the caller accessing an absent field, not with the snapshot data itself.

Solutions

1. Check the snapshot type/status before calling getFileName(); only completed or file-aware snapshots carry the name
2. Obtain the filename from the FileDownloadTask/DownloadStatusTask or the download database rather than from a snapshot that may lack it
3. Catch NoFieldException when iterating heterogeneous snapshots and skip or default the field
4. When creating snapshots that consumers will query for filenames, use a snapshot variant that includes the filename field

When it happens

Trigger: Thrown at library/src/main/java/com/liulishuo/filedownloader/message/MessageSnapshot.java:88 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of lingochamp/FileDownloader@6237a8cac1 (2026-09-08). Data as JSON: /api/errors/fe4f6f65940a2728. Report an issue: GitHub.

Appendix: source

Thrown at library/src/main/java/com/liulishuo/filedownloader/message/MessageSnapshot.java:88

    @Override
    public int getSmallSofarBytes() {
        throw new NoFieldException("getSmallSofarBytes", this);
    }

    @Override
    public int getSmallTotalBytes() {
        throw new NoFieldException("getSmallTotalBytes", this);
    }

    @Override
    public boolean isReusedDownloadedFile() {
        throw new NoFieldException("isReusedDownloadedFile", this);
    }

    @Override
    public String getFileName() {
        throw new NoFieldException("getFileName", this);
    }

    @Override
    public boolean isLargeFile() {
        return isLargeFile;
    }


    public interface IWarnMessageSnapshot {
        MessageSnapshot turnToPending();
    }


    @Override
    public int describeContents() {
        return 0;
    }

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