Honor Java Expression's context when creating Watches by SougandhS · Pull Request #926 · eclipse-jdt/eclipse.jdt.debug

SougandhS · 2026-03-30T06:59:25Z

When selecting a field under an object, both the Watch command and Drag & Drop previously created a non-contextual expression using only the field name, which caused evaluation failures. This fix ensures that both Watch and Drag & Drop now generate proper context-aware expressions such as myobj.myfield instead of just the field name.

Platform changes :
eclipse-platform/eclipse.platform#2311

Fixes : https://bugs.eclipse.org/bugs/show_bug.cgi?id=321289

What it does

How to test

Author checklist

I have thoroughly tested my changes
The change is following the coding conventions
I have signed the Eclipse Contributor Agreement (ECA)

...bug.ui/ui/org/eclipse/jdt/internal/debug/ui/heapwalking/JavaNestedWatchExpressionFilter.java

trancexpress · 2026-03-30T08:12:03Z

I think here we can add a test, once eclipse-platform/eclipse.platform#2311 is merged.

trancexpress · 2026-03-31T06:25:50Z

@SougandhS I can't seem to run the tests in WatchExpressionTests from Eclipse:

junit.framework.AssertionFailedError: Watch expression did not change
	at junit.framework.Assert.fail(Assert.java:57)
	at junit.framework.Assert.assertTrue(Assert.java:22)
	at junit.framework.Assert.assertNotNull(Assert.java:256)
	at junit.framework.TestCase.assertNotNull(TestCase.java:399)
	at org.eclipse.jdt.debug.tests.core.WatchExpressionTests.testDeferredExpression(WatchExpressionTests.java:65)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
	at junit.framework.TestCase.runTest(TestCase.java:177)
	at junit.framework.TestCase.runBare(TestCase.java:142)
	at org.eclipse.jdt.debug.tests.AbstractDebugTest.runBare(AbstractDebugTest.java:2990)
	at junit.framework.TestResult$1.protect(TestResult.java:122)
	at junit.framework.TestResult.runProtected(TestResult.java:142)
	at junit.framework.TestResult.run(TestResult.java:125)
	at junit.framework.TestCase.run(TestCase.java:130)
	at junit.framework.TestSuite.runTest(TestSuite.java:241)
	at junit.framework.TestSuite.run(TestSuite.java:236)
	at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:90)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:93)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:520)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:748)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:443)
	at org.eclipse.pde.internal.junit.runtime.RemotePluginTestRunner.main(RemotePluginTestRunner.java:126)
	at org.eclipse.pde.internal.junit.runtime.PlatformUITestHarness.lambda$0(PlatformUITestHarness.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.E4Testable.lambda$1(E4Testable.java:127)
	at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:40)
	at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:132)
	at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:5037)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4500)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1160)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1051)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:153)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:684)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:583)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:174)
	at org.eclipse.pde.internal.junit.runtime.NonUIThreadTestApplication.start(NonUIThreadTestApplication.java:58)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:219)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:149)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:115)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:467)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:298)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:615)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:563)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1415)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1387)

java.lang.NullPointerException: Cannot invoke "Object.toString()" because the return value of "org.eclipse.debug.core.model.IWatchExpression.getValue()" is null
	at org.eclipse.jdt.debug.tests.core.WatchExpressionTests.testExpressionContext(WatchExpressionTests.java:190)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
	at junit.framework.TestCase.runTest(TestCase.java:177)
	at junit.framework.TestCase.runBare(TestCase.java:142)
	at org.eclipse.jdt.debug.tests.AbstractDebugTest.runBare(AbstractDebugTest.java:2990)
	at junit.framework.TestResult$1.protect(TestResult.java:122)
	at junit.framework.TestResult.runProtected(TestResult.java:142)
	at junit.framework.TestResult.run(TestResult.java:125)
	at junit.framework.TestCase.run(TestCase.java:130)
	at junit.framework.TestSuite.runTest(TestSuite.java:241)
	at junit.framework.TestSuite.run(TestSuite.java:236)
	at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:90)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:93)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:520)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:748)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:443)
	at org.eclipse.pde.internal.junit.runtime.RemotePluginTestRunner.main(RemotePluginTestRunner.java:126)
	at org.eclipse.pde.internal.junit.runtime.PlatformUITestHarness.lambda$0(PlatformUITestHarness.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.E4Testable.lambda$1(E4Testable.java:127)
	at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:40)
	at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:132)
	at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:5037)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4500)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1160)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1051)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:153)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:684)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:583)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:174)
	at org.eclipse.pde.internal.junit.runtime.NonUIThreadTestApplication.start(NonUIThreadTestApplication.java:58)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:219)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:149)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:115)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:467)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:298)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:615)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:563)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1415)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1387)

Do you also see this? Since the tests pass in the CI environment, I'll open a new issue for this - if you see the same problem.

SougandhS · 2026-03-31T06:44:17Z

Do you also see this? Since the tests pass in the CI environment, I'll open a new issue for this - if you see the same problem.

I did get

java.lang.NullPointerException: Cannot invoke "Object.toString()" because the return value of "org.eclipse.debug.core.model.IWatchExpression.getValue()" is null
	at org.eclipse.jdt.debug.tests.core.WatchExpressionTests.testExpressionContext(WatchExpressionTests.java:190)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
	at junit.framework.TestCase.runTest(TestCase.java:177)
	at junit.framework.TestCase.runBare(TestCase.java:142)
	at org.eclipse.jdt.debug.tests.AbstractDebugTest.runBare(AbstractDebugTest.java:2990)
	at junit.framework.TestResult$1.protect(TestResult.java:122)
	at junit.framework.TestResult.runProtected(TestResult.java:142)
	at junit.framework.TestResult.run(TestResult.java:125)

But it was resolved once I used DebugElementEventWaiter waiter = new ExpressionWaiter(DebugEvent.CHANGE, expression);

Then all tests ran successfully

SougandhS · 2026-03-31T06:45:20Z

Thank you for the approval @trancexpress, I'll soon merge this 👍

trancexpress · 2026-03-31T06:49:17Z

Then all tests ran successfully

Maybe something from the plug-ins I have in my workspace then.

trancexpress · 2026-03-31T08:00:39Z

Thank you for the approval @trancexpress, I'll soon merge this 👍

Please also squash the commits, no need for two commits.

When selecting a field under an object, both the Watch command and Drag & Drop previously created a non-contextual expression using only the field name, which caused evaluation failures. This fix ensures that both Watch and Drag & Drop now generate proper context-aware expressions such as myobj.myfield instead of just the field name. Platform changes : eclipse-platform/eclipse.platform#2311 Fixes : https://bugs.eclipse.org/bugs/show_bug.cgi?id=321289

SougandhS · 2026-04-01T01:33:45Z

Will include this in N&N once eclipse-platform/eclipse.platform#2311 is merged 👍

SougandhS mentioned this pull request Mar 30, 2026

Honor expression context when creating Watches eclipse-platform/eclipse.platform#2311

Merged

trancexpress reviewed Mar 30, 2026

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trancexpress reviewed Mar 30, 2026

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SougandhS force-pushed the ExpCOntext branch from 8770dc7 to baac137 Compare March 30, 2026 08:27

trancexpress approved these changes Mar 31, 2026

View reviewed changes

SougandhS force-pushed the ExpCOntext branch from 6281898 to 4cff4e5 Compare March 31, 2026 08:14

SougandhS merged commit e717a57 into eclipse-jdt:master Apr 1, 2026
13 checks passed

SougandhS deleted the ExpCOntext branch April 1, 2026 01:31

SougandhS mentioned this pull request Apr 2, 2026

Add N&N for Context Aware Watch Expressions eclipse-platform/www.eclipse.org-eclipse#514

Merged

SougandhS added this to the 4.40 M1 milestone Apr 2, 2026

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Honor Java Expression's context when creating Watches#926

Honor Java Expression's context when creating Watches#926
SougandhS merged 1 commit intoeclipse-jdt:masterfrom
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SougandhS commented Mar 30, 2026 •

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