fix(android): Handle default-package ANR frame modules (JAVA-696)

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Fixes
+
+- Prevents inclusion of `null.` prefix before default-package class names when parsing Java and JNI frames from Android ANR thread dumps ([#5979](https://github.com/getsentry/sentry-java/pull/5979))
+
 ### Dependencies
 
 - Bump Native SDK from v0.16.2 to v0.16.3 ([#5962](https://github.com/getsentry/sentry-java/pull/5962))

sentry-android-core/src/main/java/io/sentry/android/core/internal/threaddump/ThreadDumpParser.java

@@ -275,7 +275,7 @@ private SentryStackTrace parseStacktrace(
         final SentryStackFrame frame = new SentryStackFrame();
         final String packageName = javaRe.group(1);
         final String className = javaRe.group(2);
-        final String module = String.format("%s.%s", packageName, className);
+        final String module = toModuleName(packageName, className);
         frame.setModule(module);
         frame.setFunction(javaRe.group(3));
         frame.setFilename(javaRe.group(4));
@@ -312,7 +312,7 @@ private SentryStackTrace parseStacktrace(
         final SentryStackFrame frame = new SentryStackFrame();
         final String packageName = jniRe.group(1);
         final String className = jniRe.group(2);
-        final String module = String.format("%s.%s", packageName, className);
+        final String module = toModuleName(packageName, className);
         frame.setModule(module);
         frame.setFunction(jniRe.group(3));
         frame.setInApp(stackTraceFactory.isInApp(module));
@@ -390,6 +390,11 @@ private SentryStackTrace parseStacktrace(
     return stackTrace;
   }
 
+  private @NotNull String toModuleName(
+      final @Nullable String packageName, final @NotNull String className) {
+    return packageName == null || packageName.isEmpty() ? className : packageName + "." + className;
+  }
+
   private void markThreads() {
     for (final @NotNull SentryThread thread : threads) {
       if (Boolean.TRUE.equals(thread.isMain())) {

sentry-android-core/src/test/java/io/sentry/android/core/internal/threaddump/ThreadDumpParserTest.kt

@@ -2,7 +2,9 @@ package io.sentry.android.core.internal.threaddump
 
 import io.sentry.SentryLockReason
 import io.sentry.SentryOptions
+import java.io.BufferedReader
 import java.io.File
+import java.io.StringReader
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
@@ -219,6 +221,56 @@ class ThreadDumpParserTest {
     assertEquals("main", threads.first().name)
   }
 
+  @Test
+  fun `uses class name as module when a Java frame has no package`() {
+    val lines =
+      Lines.readLines(
+        BufferedReader(
+          StringReader(
+            """
+            ----- pid 123 at 2023-04-04 22:06:31.064728684+0200 -----
+            "main" prio=5 tid=1 Runnable
+              | sysTid=123 nice=-10 cgrp=top-app sched=0/0 handle=0x7deceb74f8
+              at MainActivity.run(MainActivity.java:177)
+            """
+              .trimIndent()
+          )
+        )
+      )
+    val parser = ThreadDumpParser(SentryOptions(), false)
+
+    parser.parse(lines)
+
+    val frame = parser.threads.single().stacktrace!!.frames!!.last()
+    assertEquals("MainActivity", frame.module)
+  }
+
+  @Test
+  fun `uses class name as module when a JNI frame has no package`() {
+    val lines =
+      Lines.readLines(
+        BufferedReader(
+          StringReader(
+            """
+            ----- pid 123 at 2023-04-04 22:06:31.064728684+0200 -----
+            "main" prio=5 tid=1 Runnable
+              | sysTid=123 nice=-10 cgrp=top-app sched=0/0 handle=0x7deceb74f8
+              at MainActivity.nativeRun(Native method)
+            """
+              .trimIndent()
+          )
+        )
+      )
+    val parser = ThreadDumpParser(SentryOptions(), false)
+
+    parser.parse(lines)
+
+    val frame = parser.threads.single().stacktrace!!.frames!!.last()
+    assertEquals("MainActivity", frame.module)
+    assertEquals("nativeRun", frame.function)
+    assertEquals(true, frame.isNative)
+  }
+
   @Test
   fun `thread dump garbage`() {
     val lines = Lines.readLines(File("src/test/resources/thread_dump_bad_data.txt"))