gyf-dev/ImmersionBar · error · NullPointerException

message (variable, e.g. "activity is null", "fragment is…

Error message

message (variable, e.g. "activity is null", "fragment is null")

What it means

RequestManagerRetriever.checkNotNull throws NullPointerException with a caller-provided message (e.g. "activity is null", "fragment is null") when an argument to get()/supportFragmentGet() etc. is null. The library cannot attach its hidden support fragment without a live context owner, so it fails fast.

Solutions

1. Ensure a non-null, started Activity or attached Fragment is passed to get()
2. Unwrap ContextWrapper to verify an Activity exists before calling
3. Null-check the source (getActivity()/getParentFragment()) and retry after attachment

Example fix

// before
Fragment f = retriever.get(fragment.getActivity()); // activity may be null
// after
Activity activity = fragment.getActivity();
if (activity != null) {
    Fragment f = retriever.get(activity);
}

if (activity != null) { retriever.get(activity); }

Activity unwrapActivity(Context c) { while (c instanceof ContextWrapper) { if (c instanceof Activity) return (Activity) c; c = ((ContextWrapper) c).getBaseContext(); } return null; }

try { retriever.get(context); } catch (NullPointerException e) { Log.e(TAG, "no activity available: " + e.getMessage()); }

When it happens

Trigger: Calling the retriever's get(Context)/get(Fragment) with a null Activity, null Fragment, or a context whose unwrapped activity is null (Application context, detached fragment).

Common situations: Requesting fragment manager access from a detached Fragment; passing applicationContext where an Activity is required; lifecycle races where the fragment was detached before the lookup; manually invoking retriever code rather than the public facade.

Related errors

• Owner must be attached to a Window.
• Fragment must be attached to an Activity.
• View参数不能为空
• tag不能为空
• Fragment请实现ImmersionOwner接口

AI-assisted analysis of gyf-dev/ImmersionBar@8cac10cd83 (2026-09-08). Data as JSON: /api/errors/ddbce46f1223280a. Report an issue: GitHub.

Appendix: source

Thrown at immersionbar/src/main/java/com/gyf/immersionbar/RequestManagerRetriever.java:379

                putPendingSupportFragment(fm, tag, fragment);
                fm.beginTransaction().add(fragment, tag).commitAllowingStateLoss();
                mHandler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER, new PendingFragment(fm, tag)).sendToTarget();
            }
        }
        if (destroy) {
            if (mPendingSupportRemoveFragments.get(tag) == null) {
                mPendingSupportRemoveFragments.put(tag, fragment);
                fm.beginTransaction().remove(fragment).commitAllowingStateLoss();
                mHandler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER_REMOVE, tag).sendToTarget();
            }
            return null;
        }
        return fragment;
    }

    private static <T> void checkNotNull(@Nullable T arg, @NonNull String message) {
        if (arg == null) {
            throw new NullPointerException(message);
        }
    }

    private static class PendingFragment {
        final Object fragmentManager;
        final String tag;

        PendingFragment(Object fragmentManager, String tag) {
            this.fragmentManager = fragmentManager;
            this.tag = tag;
        }
    }
}

View on GitHub (pinned to 8cac10cd83)