Tolerate weird class names, as seen in functionaljava (#4401)

* Tolerate weird class names, as seen in functionaljava They are using `fj.data.$`, which then leads to an empty String. * Add test as suggested * Test in isolation
openrewrite · Aug 9, 2024 · 97f049c · 97f049c
1 parent 3a12433
commit 97f049c
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Showing 2 changed files with 10 additions and 3 deletions.
diff --git a/rewrite-java-test/src/test/java/org/openrewrite/java/marker/JavaSourceSetTest.java b/rewrite-java-test/src/test/java/org/openrewrite/java/marker/JavaSourceSetTest.java
@@ -70,4 +70,10 @@ void gavCoordinateFromMaven() {
         assertThat(gavFromPath(Paths.get("C:/Users/Sam/.m2/repository/org/openrewrite/rewrite-core/8.32.0/rewrite-core-8.32.0.jar")))
           .isEqualTo("org.openrewrite:rewrite-core:8.32.0");
     }
+
+    @Test
+    @Issue("https://github.com/openrewrite/rewrite/pull/4401")
+    void tolerateWeirdClassNames(){
+        assertThat(JavaSourceSet.isDeclarable("fj.data.$")).isFalse();
+    }
 }
diff --git a/rewrite-java/src/main/java/org/openrewrite/java/marker/JavaSourceSet.java b/rewrite-java/src/main/java/org/openrewrite/java/marker/JavaSourceSet.java
@@ -327,10 +327,11 @@ private static String entryNameToClassName(String entryName) {
                 .replace('/', '.');
     }
 
-    private static boolean isDeclarable(String className) {
+    static boolean isDeclarable(String className) {
         int dotIndex = Math.max(className.lastIndexOf("."), className.lastIndexOf('$'));
         className = className.substring(dotIndex + 1);
-        char firstChar = className.charAt(0);
-        return Character.isJavaIdentifierPart(firstChar) && !Character.isDigit(firstChar);
+        return !className.isEmpty() &&
+               Character.isJavaIdentifierPart(className.charAt(0)) &&
+               !Character.isDigit(className.charAt(0));
     }
 }