Replace LanguageTag.isLanguage with public API

Libcore will be modulized and updatable, and thus
avoid using libcore's private API.

No behavior change.

Bug: 154796679
Test: HdmiCecControllerTest#testIsLanguage
Change-Id: If9cc4df26182141d292a218a5f4cba442e802309

services/core/java/com/android/server/hdmi/HdmiCecController.java

@@ -26,6 +26,8 @@ import android.hardware.tv.cec.V1_0.IHdmiCec.getPhysicalAddressCallback;
 import android.hardware.tv.cec.V1_0.IHdmiCecCallback;
 import android.hardware.tv.cec.V1_0.Result;
 import android.hardware.tv.cec.V1_0.SendMessageResult;
+import android.icu.util.IllformedLocaleException;
+import android.icu.util.ULocale;
 import android.os.Handler;
 import android.os.IHwBinder;
 import android.os.Looper;
@@ -33,6 +35,7 @@ import android.os.RemoteException;
 import android.stats.hdmi.HdmiStatsEnums;
 import android.util.Slog;
 
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.FrameworkStatsLog;
 import com.android.internal.util.IndentingPrintWriter;
 import com.android.server.hdmi.HdmiAnnotations.IoThreadOnly;
@@ -49,8 +52,6 @@ import java.util.List;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.function.Predicate;
 
-import sun.util.locale.LanguageTag;
-
 /**
  * Manages HDMI-CEC command and behaviors. It converts user's command into CEC command
  * and pass it to CEC HAL so that it sends message to other device. For incoming
@@ -352,12 +353,30 @@ final class HdmiCecController {
     @ServiceThreadOnly
     void setLanguage(String language) {
         assertRunOnServiceThread();
-        if (!LanguageTag.isLanguage(language)) {
+        if (!isLanguage(language)) {
             return;
         }
         mNativeWrapperImpl.nativeSetLanguage(language);
     }
 
+    /**
+     * Returns true if the language code is well-formed.
+     */
+    @VisibleForTesting static boolean isLanguage(String language) {
+        // Handle null and empty string because because ULocale.Builder#setLanguage accepts them.
+        if (language == null || language.isEmpty()) {
+            return false;
+        }
+
+        ULocale.Builder builder = new ULocale.Builder();
+        try {
+            builder.setLanguage(language);
+            return true;
+        } catch (IllformedLocaleException e) {
+            return false;
+        }
+    }
+
     /**
      * Configure ARC circuit in the hardware logic to start or stop the feature.
      *

services/tests/servicestests/src/com/android/server/hdmi/HdmiCecControllerTest.java

@@ -30,6 +30,8 @@ import static com.android.server.hdmi.Constants.ADDR_TV;
 import static com.android.server.hdmi.Constants.ADDR_UNREGISTERED;
 
 import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
 
 import android.content.Context;
 import android.hardware.hdmi.HdmiControlManager;
@@ -257,4 +259,19 @@ public class HdmiCecControllerTest {
         mTestLooper.dispatchAll();
         assertEquals(ADDR_UNREGISTERED, mLogicalAddress);
     }
+
+    @Test
+    public void testIsLanguage() {
+        assertTrue(HdmiCecController.isLanguage("en"));
+        assertTrue(HdmiCecController.isLanguage("eng"));
+        assertTrue(HdmiCecController.isLanguage("ger"));
+        assertTrue(HdmiCecController.isLanguage("zh"));
+        assertTrue(HdmiCecController.isLanguage("zhi"));
+        assertTrue(HdmiCecController.isLanguage("zho"));
+
+        assertFalse(HdmiCecController.isLanguage(null));
+        assertFalse(HdmiCecController.isLanguage(""));
+        assertFalse(HdmiCecController.isLanguage("e"));
+        assertFalse(HdmiCecController.isLanguage("一")); // language code must be ASCII
+    }
 }