added Android friedly init.

sentry-android-core/src/main/java/io/sentry/android/core/SentryAndroid.java

@@ -0,0 +1,20 @@
+package io.sentry.android.core;
+
+import android.content.Context;
+import io.sentry.core.Sentry;
+import io.sentry.core.util.NonNull;
+
+/** Sentry initialization class */
+public final class SentryAndroid {
+
+  private SentryAndroid() {}
+
+  /**
+   * Sentry initialization method if auto-init is disabled
+   *
+   * @param context Application. context
+   */
+  public static void init(@NonNull final Context context) {
+    Sentry.init(options -> AndroidOptionsInitializer.init(options, context));
+  }
+}

sentry-android-core/src/test/java/io/sentry/android/core/SentryAndroidTest.kt

@@ -0,0 +1,63 @@
+package io.sentry.android.core
+
+import android.content.Context
+import android.content.pm.ApplicationInfo
+import android.content.pm.PackageManager
+import android.os.Bundle
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.nhaarman.mockitokotlin2.doReturn
+import com.nhaarman.mockitokotlin2.mock
+import com.nhaarman.mockitokotlin2.whenever
+import io.sentry.core.Sentry
+import java.io.File
+import kotlin.test.BeforeTest
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class SentryAndroidTest {
+    private lateinit var context: Context
+
+    @BeforeTest
+    fun `set up`() {
+        context = ApplicationProvider.getApplicationContext()
+        Sentry.close()
+    }
+
+    @Test
+    fun `when applicationId is defined, dsn in meta-data, SDK initializes`() {
+        assertFalse(Sentry.isEnabled())
+
+        val mockContext = createMockContext()
+        val metaData = Bundle()
+        mockMetaData(mockContext, metaData)
+
+        metaData.putString(ManifestMetadataReader.DSN_KEY, "https://[email protected]/123")
+
+        SentryAndroid.init(mockContext)
+
+        assertTrue(Sentry.isEnabled())
+    }
+
+    private fun createMockContext(): Context {
+        val mockContext = mock<Context> {
+            on { applicationContext } doReturn context
+        }
+        whenever(mockContext.cacheDir).thenReturn(File("${File.separator}cache"))
+        return mockContext
+    }
+
+    private fun mockMetaData(mockContext: Context, metaData: Bundle) {
+        val mockPackageManager: PackageManager = mock()
+        val mockApplicationInfo: ApplicationInfo = mock()
+
+        whenever(mockContext.packageName).thenReturn("io.sentry.sample.test")
+        whenever(mockContext.packageManager).thenReturn(mockPackageManager)
+        whenever(mockPackageManager.getApplicationInfo(mockContext.packageName, PackageManager.GET_META_DATA)).thenReturn(mockApplicationInfo)
+
+        mockApplicationInfo.metaData = metaData
+    }
+}

sentry-sample/src/main/AndroidManifest.xml

@@ -4,6 +4,7 @@
     package="io.sentry.sample">
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
   <application
+    android:name=".MyApplication"
     android:allowBackup="false"
     android:icon="@mipmap/ic_launcher"
     android:label="@string/app_name"

sentry-sample/src/main/java/io/sentry/sample/MyApplication.java

@@ -0,0 +1,17 @@
+package io.sentry.sample;
+
+import android.app.Application;
+
+// import io.sentry.android.core.SentryAndroid;
+
+/** Apps. main Application. */
+public class MyApplication extends Application {
+
+  @Override
+  public void onCreate() {
+    super.onCreate();
+
+    // how to init. Sentry manually
+    // SentryAndroid.init(this);
+  }
+}