bilibili/DanmakuFlameMaster · error · IllegalArgumentException

context is null

Error message

context is null

What it means

DrawTask's constructor requires a non-null DanmakuContext; it immediately derives the Displayer and DanmakuRenderer from it, so a null context would make the whole draw pipeline unusable. The library fails fast with IllegalArgumentException rather than NPE-ing later during rendering.

Solutions

1. Create a DanmakuContext first with DanmakuContext.create() and pass it to the constructor.
2. Check that the variable passed as context is assigned before the DrawTask/DanmakuView setup runs.
3. If using DanmakuView, ensure prepare() is called after the view has initialized its own context, not with a hand-built null context.
4. Wrap the setup call in a null check or Objects.requireNonNull(context) at the call site to catch it early.

Example fix

// before
DrawTask task = new DrawTask(timer, null, listener);
// after
DanmakuContext context = DanmakuContext.create();
DrawTask task = new DrawTask(timer, context, listener);

if (context == null) { throw new IllegalStateException("call DanmakuContext.create() before constructing DrawTask"); }
DrawTask task = new DrawTask(timer, context, listener);

boolean hasContext = (context != null);

try {
    DrawTask task = new DrawTask(timer, context, listener);
} catch (IllegalArgumentException e) {
    Log.e(TAG, "DrawTask needs a DanmakuContext", e);
    context = DanmakuContext.create();
}

When it happens

Trigger: Calling new DrawTask(timer, null, taskListener), or creating it indirectly (e.g. DanmakuView/DanmakuSurfaceView initialize paths) after DanmakuContext was never created via DanmakuContext.create().

Common situations: Forgetting to call DanmakuContext.create() before preparing the danmaku view; passing a context variable that is assigned asynchronously and still null when the draw task is built; custom controller code constructing DrawTask manually.

Related errors

• itemView may not be null
• input stream cannot be null!
• The pool limit must be > 0

AI-assisted analysis of bilibili/DanmakuFlameMaster@e2846461a0 (2026-09-10). Data as JSON: /api/errors/567acb1d09435a64. Report an issue: GitHub.

Appendix: source

Thrown at DanmakuFlameMaster/src/main/java/master/flame/danmaku/controller/DrawTask.java:87

    private BaseDanmaku mLastDanmaku;

    private Danmakus mLiveDanmakus = new Danmakus(Danmakus.ST_BY_LIST);

    private IDanmakus mRunningDanmakus;

    private boolean mRequestRender;

    private ConfigChangedCallback mConfigChangedCallback = new ConfigChangedCallback() {
        @Override
        public boolean onDanmakuConfigChanged(DanmakuContext config, DanmakuConfigTag tag, Object... values) {
            return DrawTask.this.onDanmakuConfigChanged(config, tag, values);
        }
    };

    public DrawTask(DanmakuTimer timer, DanmakuContext context,
            TaskListener taskListener) {
        if (context == null) {
            throw new IllegalArgumentException("context is null");
        }
        mContext = context;
        mDisp = context.getDisplayer();
        mTaskListener = taskListener;
        mRenderer = new DanmakuRenderer(context);
        mRenderer.setOnDanmakuShownListener(new IRenderer.OnDanmakuShownListener() {

            @Override
            public void onDanmakuShown(BaseDanmaku danmaku) {
                if (mTaskListener != null) {
                    mTaskListener.onDanmakuShown(danmaku);
                }
            }
        });
        mRenderer.setVerifierEnabled(mContext.isPreventOverlappingEnabled() || mContext.isMaxLinesLimited());
        initTimer(timer);
        Boolean enable = mContext.isDuplicateMergingEnabled();
        if (enable != null) {

View on GitHub (pinned to e2846461a0)