didi/DoKit · error · IllegalArgumentException

Context must not be null.

Error message

Context must not be null.

What it means

DokitPicasso.Builder's constructor requires a non-null Context (IllegalArgumentException('Context must not be null.') otherwise) because the whole image pipeline — cache, resource decoding, dispatcher — derives from it. It immediately stores context.getApplicationContext(), which also fails fast if a non-null but broken Context wrapper is passed. This is the earliest possible failure in Picasso setup, which is why it is guarded first.

Solutions

1. Defer building until the context is real: fragment onAttach / Activity onCreate
2. Use context.getApplicationContext() explicitly when wiring from a short-lived object
3. In DI (Hilt/Dagger), make the Context provider @NonNull and fail at graph validation

Example fix

// before
public AvatarLoader(Context ctx) {
  this.picasso = new DokitPicasso.Builder(ctx).build(); // ctx null in ctor
}

// after
public AvatarLoader(Context ctx) {
  this.picasso = new DokitPicasso.Builder(
      Objects.requireNonNull(ctx, "context").getApplicationContext()).build();
}

if (context != null) {
  DokitPicasso picasso = new DokitPicasso.Builder(context.getApplicationContext()).build();
}

java.util.Objects.requireNonNull;

try {
  picasso = new DokitPicasso.Builder(context).build();
} catch (IllegalArgumentException e) {
  if ("Context must not be null.".equals(e.getMessage())) {
    throw new IllegalStateException("Picasso built before context attached", e);
  }
  throw e;
}

When it happens

Trigger: new DokitPicasso.Builder(null) from code where the context field is not yet assigned (e.g. fragment constructor before onAttach); Mockito/mock Context returning null from getApplicationContext(); refactoring static helpers that used to receive context and now get null.

Common situations: Fragment/view constructors invoked before attachment; unit tests passing null for speed; DI misconfiguration supplying a null provider.

Related errors

• Bitmap config must not be null.
• Downloader must not be null.
• Error image may not be null.
• file == null
• Memory policy cannot be null.

AI-assisted analysis of didi/DoKit@626827cddb (2026-08-14). Data as JSON: /api/errors/e9777ee7f095ce68. Report an issue: GitHub.

Appendix: source

Thrown at Android/dokit/src/main/java/com/didichuxing/doraemonkit/picasso/DokitPicasso.java:702

  /** Fluent API for creating {@link DokitPicasso} instances. */
  @SuppressWarnings("UnusedDeclaration") // Public API.
  public static class Builder {
    private final Context context;
    private Downloader downloader;
    private ExecutorService service;
    private Cache cache;
    private Listener listener;
    private RequestTransformer transformer;
    private List<RequestHandler> requestHandlers;
    private Bitmap.Config defaultBitmapConfig;

    private boolean indicatorsEnabled;
    private boolean loggingEnabled;

    /** Start building a new {@link DokitPicasso} instance. */
    public Builder(Context context) {
      if (context == null) {
        throw new IllegalArgumentException("Context must not be null.");
      }
      this.context = context.getApplicationContext();
    }

    /**
     * Specify the default {@link Bitmap.Config} used when decoding images. This can be overridden
     * on a per-request basis using {@link RequestCreator#config(Bitmap.Config) config(..)}.
     */
    public Builder defaultBitmapConfig(Bitmap.Config bitmapConfig) {
      if (bitmapConfig == null) {
        throw new IllegalArgumentException("Bitmap config must not be null.");
      }
      this.defaultBitmapConfig = bitmapConfig;
      return this;
    }

    /** Specify the {@link Downloader} that will be used for downloading images. */
    public Builder downloader(Downloader downloader) {

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