Adds a LanguageDetector Java API.

PiperOrigin-RevId: 522895455

mediapipe/tasks/javatests/com/google/mediapipe/tasks/text/languagedetector/AndroidManifest.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.google.mediapipe.tasks.text.languagedetectortest"
+    android:versionCode="1"
+    android:versionName="1.0" >
+
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
+
+    <uses-sdk android:minSdkVersion="24"
+        android:targetSdkVersion="30" />
+
+    <application
+        android:label="languagedetectortest"
+        android:name="android.support.multidex.MultiDexApplication"
+        android:taskAffinity="">
+        <uses-library android:name="android.test.runner" />
+    </application>
+
+    <instrumentation
+        android:name="com.google.android.apps.common.testing.testrunner.GoogleInstrumentationTestRunner"
+        android:targetPackage="com.google.mediapipe.tasks.text.languagedetectortest" />
+
+</manifest>

mediapipe/tasks/javatests/com/google/mediapipe/tasks/text/languagedetector/BUILD

@@ -0,0 +1,19 @@
+# Copyright 2023 The MediaPipe Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+package(default_visibility = ["//mediapipe/tasks:internal"])
+
+licenses(["notice"])
+
+# TODO: Enable this in OSS

mediapipe/tasks/javatests/com/google/mediapipe/tasks/text/languagedetector/LanguageDetectorTest.java

@@ -0,0 +1,110 @@
+// Copyright 2023 The MediaPipe Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.mediapipe.tasks.text.languagedetector;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import androidx.test.core.app.ApplicationProvider;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.mediapipe.framework.MediaPipeException;
+import com.google.mediapipe.tasks.core.BaseOptions;
+import com.google.mediapipe.tasks.core.TestUtils;
+import com.google.mediapipe.tasks.text.languagedetector.LanguageDetector.LanguageDetectorOptions;
+import java.util.Arrays;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Test for {@link LanguageDetector}/ */
+@RunWith(AndroidJUnit4.class)
+public class LanguageDetectorTest {
+  private static final String MODEL_FILE = "language_detector.tflite";
+
+  @Test
+  public void options_failsWithNegativeMaxResults() throws Exception {
+    IllegalArgumentException exception =
+        assertThrows(
+            IllegalArgumentException.class,
+            () ->
+                LanguageDetectorOptions.builder()
+                    .setBaseOptions(BaseOptions.builder().setModelAssetPath(MODEL_FILE).build())
+                    .setMaxResults(-1)
+                    .build());
+    assertThat(exception).hasMessageThat().contains("If specified, maxResults must be > 0");
+  }
+
+  @Test
+  public void options_failsWithBothAllowlistAndDenylist() throws Exception {
+    IllegalArgumentException exception =
+        assertThrows(
+            IllegalArgumentException.class,
+            () ->
+                LanguageDetectorOptions.builder()
+                    .setBaseOptions(BaseOptions.builder().setModelAssetPath(MODEL_FILE).build())
+                    .setCategoryAllowlist(Arrays.asList("foo"))
+                    .setCategoryDenylist(Arrays.asList("bar"))
+                    .build());
+    assertThat(exception)
+        .hasMessageThat()
+        .contains("Category allowlist and denylist are mutually exclusive");
+  }
+
+  @Test
+  public void create_failsWithMissingModel() throws Exception {
+    String nonExistentFile = "/path/to/non/existent/file";
+    MediaPipeException exception =
+        assertThrows(
+            MediaPipeException.class,
+            () ->
+                LanguageDetector.createFromFile(
+                    ApplicationProvider.getApplicationContext(), nonExistentFile));
+    assertThat(exception).hasMessageThat().contains(nonExistentFile);
+  }
+
+  @Test
+  public void detect_succeedsWithL2CModel() throws Exception {
+    LanguageDetector languageDetector =
+        LanguageDetector.createFromFile(ApplicationProvider.getApplicationContext(), MODEL_FILE);
+    LanguageDetectorResult enResult =
+        languageDetector.detect("To be, or not to be, that is the question");
+    assertThat(enResult.languagesAndScores().size()).isEqualTo(1);
+    assertThat(enResult.languagesAndScores().get(0))
+        .isEqualTo(LanguagePrediction.create("en", 0.9998559f));
+    LanguageDetectorResult frResult =
+        languageDetector.detect(
+            "Il y a beaucoup de bouches qui parlent et fort peu de têtes qui pensent.");
+    assertThat(frResult.languagesAndScores().size()).isEqualTo(1);
+    assertThat(frResult.languagesAndScores().get(0))
+        .isEqualTo(LanguagePrediction.create("fr", 0.9997813f));
+    LanguageDetectorResult ruResult = languageDetector.detect("это какой-то английский язык");
+    assertThat(ruResult.languagesAndScores().size()).isEqualTo(1);
+    assertThat(ruResult.languagesAndScores().get(0))
+        .isEqualTo(LanguagePrediction.create("ru", 0.9933616f));
+  }
+
+  @Test
+  public void detect_succeedsWithFileObject() throws Exception {
+    LanguageDetector languageDetector =
+        LanguageDetector.createFromFile(
+            ApplicationProvider.getApplicationContext(),
+            TestUtils.loadFile(ApplicationProvider.getApplicationContext(), MODEL_FILE));
+    LanguageDetectorResult mixedResult = languageDetector.detect("分久必合合久必分");
+    assertThat(mixedResult.languagesAndScores().size()).isEqualTo(2);
+    assertThat(mixedResult.languagesAndScores().get(0))
+        .isEqualTo(LanguagePrediction.create("zh", 0.50542367f));
+    assertThat(mixedResult.languagesAndScores().get(1))
+        .isEqualTo(LanguagePrediction.create("ja", 0.4816168f));
+  }
+}