Android code quality improvements

[kirklandsign]

Summary

• Fix check-after-use bug in JNI scalar type lookup: move .count() check
  before .at() so unsupported scalar types throw a Java exception instead
  of C++ std::out_of_range
• Fix initHybrid → numThreads parameter name in Module.java native
  declaration
• Fix missing space in getMethodMetadata() error message
• Modernize build config: Java 11 source/target, remove dead
  root ext properties (minSdkVersion, targetSdkVersion, compileSdkVersion,
  buildToolsVersion), update test dependencies (junit 4.13.2,
  androidx.test.ext:junit 1.2.1, androidx.test:rules 1.6.1,
  commons-io 2.18.0)

Review order: jni_layer.cpp → Module.java → build.gradle files.

Test plan

• CI (existing unit + instrumentation tests cover the JNI and Module paths)
• Build config changes are compile-time only; verified locally that Gradle
  sync succeeds

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/17636

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❌ 3 New Failures, 51 Pending, 3 Unrelated Failures

As of commit 0521e2a with merge base cf08087 ():

NEW FAILURES - The following jobs have failed:

• pull / test-mediatek-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 55b3ca8f5e54c0838485f2bd5225fbf614c8165e50541cebe79f01801cba6b61 /exec failed with exit code 2
• pull / test-openvino-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 3807b7dcceaca124b79374de1c7cff385e6b5a5430829e256cd98ac4c834df4b /exec failed with exit code 1
• pull / unittest-buck / linux / linux-job (gh)
  RuntimeError: Command docker exec -t c8957be9ef2434afd913ff170a82947373e32e2e13035e489061f245820d4a83 /exec failed with exit code 3

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• pull / test-llama-runner-linux-android / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
• pull / test-selective-build-linux / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest-buck / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 3

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[Copilot]

Pull request overview

This PR fixes a critical check-after-use bug in the JNI scalar type lookup code. The issue was that scalar_type_to_java_dtype.at(scalarType) was called before checking if the key exists in the map with .count(), causing the C++ code to throw an unhandled std::out_of_range exception and crash instead of throwing a proper Java exception.

Changes:

• Move the .count() check before the .at() lookup to prevent crashes on unsupported scalar types
• Update error message to display the actual scalar type value instead of an uninitialized jdtype variable
• Enable proper Java exception handling for unsupported tensor scalar types

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

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