didi/DoKit · error · IllegalArgumentException

Executor service must not be null.

Error message

Executor service must not be null.

What it means

DokitPicasso.Builder.executor() throws IllegalArgumentException when passed a null ExecutorService. Picasso requires a non-null executor to run background image loads. The null check is a fail-fast guard on builder configuration.

Source

Thrown at Android/dokit/src/main/java/com/didichuxing/doraemonkit/picasso/DokitPicasso.java:738

    public Builder downloader(Downloader downloader) {
      if (downloader == null) {
        throw new IllegalArgumentException("Downloader must not be null.");
      }
      if (this.downloader != null) {
        throw new IllegalStateException("Downloader already set.");
      }
      this.downloader = downloader;
      return this;
    }

    /**
     * Specify the executor service for loading images in the background.
     * <p>
     * Note: Calling {@link DokitPicasso#shutdown() shutdown()} will not shutdown supplied executors.
     */
    public Builder executor(ExecutorService executorService) {
      if (executorService == null) {
        throw new IllegalArgumentException("Executor service must not be null.");
      }
      if (this.service != null) {
        throw new IllegalStateException("Executor service already set.");
      }
      this.service = executorService;
      return this;
    }

    /** Specify the memory cache used for the most recent images. */
    public Builder memoryCache(Cache memoryCache) {
      if (memoryCache == null) {
        throw new IllegalArgumentException("Memory cache must not be null.");
      }
      if (this.cache != null) {
        throw new IllegalStateException("Memory cache already set.");
      }
      this.cache = memoryCache;
      return this;

View on GitHub (pinned to 626827cddb)

Solutions

1. Pass a non-null ExecutorService, e.g. Executors.newFixedThreadPool(n)
2. If the executor variable may be null, guard: only call executor() when the value is non-null
3. Fix the upstream provider (DI module/factory) so it returns a valid executor

Example fix

// before
builder.executor(null); // IllegalArgumentException

// after
builder.executor(Executors.newFixedThreadPool(4));

ExecutorService executor = provider.executor();
if (executor != null) { builder.executor(executor); } // or fail loudly at provider level

When it happens

Trigger: Calling builder.executor(null), often from a field or factory method that returned null (e.g. a DI-provided executor that was not initialized).

Common situations: Passing an executor obtained from a dependency container that has not been set up; test code that stubs the executor as null; conditional code that builds the executor only in some branches.

Related errors

• Memory cache must not be null.
• Listener must not be null.
• Transformer must not be null.
• RequestHandler must not be null.
• Downloader already set.

AI-assisted analysis of didi/DoKit@626827cddb (2026-08-14). Data as JSON: /api/errors/1d4cec11a39e0183. Report an issue: GitHub.