WIP: Fix Class.getMethod() to reject non-public interface methods by tomal-majumder · Pull Request #23384 · eclipse-openj9/openj9

tomal-majumder · 2026-02-20T23:22:34Z

Fix Class.getMethod() to throw NoSuchMethodException for non-public interface methods

Problem

Class.getMethod() must return only public methods or throw NoSuchMethodException as per Java specification. Previously, when invoked on interface types with non-public methods (private static or non-static), the method incorrectly returned null instead of throwing the required exception.

Root Cause

The issue was in the initialResultShouldBeReplaced code path in getMethodHelper(). When publicOnly was true but the initial result was a non-public method, and no public alternatives were found, the method returned null instead of calling throwExceptionOrReturnNull().

Tests

Test coverage added in Java9andUp/GetMethodTests.

Fixes: #22448

babsingh · 2026-02-23T15:39:24Z

jcl/src/java.base/share/classes/java/lang/Class.java

The proposed fix may not be the best way to address the reported failure.

Can you try the following fix? The comment above (in line 2057) indicates that no public method was found, which results in a null return value. The private interface method is therefore being correctly filtered. However, directly returning null here ignores the throwException input parameter, which is set to true in the case of Class.getMethod.

Suggested change

return throwExceptionOrReturnNull(throwException, name, parameterTypes);

Yes, this block does correctly filter out private interface methods. I tested the suggested change, and it produces the expected java.lang.NoSuchMethodException when a private interface method is requested via Class.getMethod().

My initial approach was to enforce the visibility constraint earlier by filtering out the private method returned by getDeclaredMethodImpl().

The initial approach is incomplete because it only filters out non-public methods in the this.isInterface() branch, but does not address the root contract violation in getMethodHelper.

Class.getMethod() must either return a public method or throw NoSuchMethodException. Currently, getMethodHelper can still return null in the initialResultShouldBeReplaced path, even when throwException == true. Your change does not modify that logic.

As a result:

it fixes the specific interface path scenario,

but it does not guarantee that getMethod() will always throw instead of returning null in all non-public cases, and

it does not cover non-interface code paths that may hit the same logic.

We are also missing test coverage. Please also add Java test cases covering these scenarios to ensure the contract is enforced consistently across both interface and non-interface paths.

babsingh · 2026-02-23T15:50:54Z

Also, the commit guidelines are not followed: https://github.com/eclipse-openj9/openj9/blob/master/CONTRIBUTING.md#commit-guidelines -> The body should be wrapped at 72 characters.

tomal-majumder · 2026-02-27T01:28:17Z

jcl/src/java.base/share/classes/java/lang/Class.java

 	if (initialResultShouldBeReplaced) {
 		// The initial result is not a public method to be searched, and no other public methods found.
-		return null;
+		return throwExceptionOrReturnNull(throwException, name, parameterTypes);


@babsingh Added tests for Class.getMethod() on private interface methods (static and non-static), which are the only cases that reach this path. Other scenarios involving superinterfaces or implementing classes are handled and rejected earlier in the method.

babsingh · 2026-02-27T21:23:04Z

test/functional/Java9andUp/src/org/openj9/test/reflect/TestInterfaceForGetMethod.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright IBM Corp. and others 2001


this reflects the year when the file was added

Suggested change

* Copyright IBM Corp. and others 2001

* Copyright IBM Corp. and others 2026

babsingh · 2026-02-27T21:23:54Z

test/functional/Java9andUp/src/org/openj9/test/reflect/TestInterfaceForGetMethod.java

+public interface TestInterfaceForGetMethod {
+
+	private static void privateStaticMethod() {
+	}
+	private void privateNonStaticMethod() {
+	}
+}


formatting nit

Suggested change

public interface TestInterfaceForGetMethod {

private static void privateStaticMethod() {

}

private void privateNonStaticMethod() {

}

}

public interface TestInterfaceForGetMethod {

private static void privateStaticMethod() {}

private void privateNonStaticMethod() {}

}

babsingh · 2026-02-27T21:24:35Z

test/functional/Java9andUp/src/org/openj9/test/reflect/GetMethodTests.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright IBM Corp. and others 2001


Suggested change

* Copyright IBM Corp. and others 2001

* Copyright IBM Corp. and others 2026

babsingh · 2026-02-27T21:27:58Z

test/functional/Java9andUp/src/org/openj9/test/reflect/TestInterfaceForGetMethod.java

+	private static void privateStaticMethod() {
+	}
+	private void privateNonStaticMethod() {
+	}


also include a test case for a public method to verify non-private behavior

babsingh · 2026-02-27T21:32:13Z

test/functional/Java9andUp/src/org/openj9/test/reflect/GetMethodTests.java

+		try {
+			TestInterfaceForGetMethod.class.getMethod("privateStaticMethod");
+			Assert.fail("Expected NoSuchMethodException for private static method in interface");
+		} catch (NoSuchMethodException e) {
+		}
+	}


the testcases can be concisely written using assertThrows. example:

openj9/test/functional/Valhalla/src_lw5/org/openj9/test/lworld/ValueTypeUnsafeTests.java

Lines 191 to 193 in a2b189d

assertThrows(NullPointerException.class, () -> {

myUnsafe.isFlatField(null);

});

Update getMethodHelper() to properly throw NoSuchMethodException when Class.getMethod() is called on non-public interface methods. Added test coverage in Java9andUp/GetMethodTests: - Private static methods in interfaces throw NoSuchMethodException - Private non-static methods in interfaces throw NoSuchMethodException - Public methods successfully returns a Method Fixes: eclipse-openj9#22448 Signed-off-by: Tomal Majumder <Tomal.Majumder@ibm.com>

tomal-majumder · 2026-02-27T23:28:07Z

Updated! Also added tests for public methods.

tomal-majumder force-pushed the fix-getMethod-issue-22448 branch from bc81b56 to a9b77e9 Compare February 20, 2026 23:28

babsingh reviewed Feb 23, 2026

View reviewed changes

tomal-majumder force-pushed the fix-getMethod-issue-22448 branch 3 times, most recently from d323ab2 to 39ac334 Compare February 27, 2026 01:11

tomal-majumder commented Feb 27, 2026

View reviewed changes

babsingh reviewed Feb 27, 2026

View reviewed changes

tomal-majumder force-pushed the fix-getMethod-issue-22448 branch from 39ac334 to fc97f64 Compare February 27, 2026 23:22

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WIP: Fix Class.getMethod() to reject non-public interface methods#23384

WIP: Fix Class.getMethod() to reject non-public interface methods#23384
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tomal-majumder:fix-getMethod-issue-22448

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	return throwExceptionOrReturnNull(throwException, name, parameterTypes);

	* Copyright IBM Corp. and others 2001
	* Copyright IBM Corp. and others 2026

	assertThrows(NullPointerException.class, () -> {
	myUnsafe.isFlatField(null);
	});

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