From 3e71ee7a59531125d36e6f94891c68a36b0e739a Mon Sep 17 00:00:00 2001
From: Shuhei Takahashi <nya@google.com>
Date: Thu, 30 Jan 2025 23:13:26 +0900
Subject: [PATCH 1/2] Improve variables view

We used to have two scopes of variables, "locals" and "arguments".
However, VM somehow returns incorrect results for
LocalVariable#isArgument(), so we presented confusing views to users.
Since it's not very important to distinguish arguments and local
variables, we now include them in the same "locals" scope.

Instead, we introduce the new "fields" scope containing fields of the
current object (aka "this").

And finally, we now support inspecting the hierarchy of objects.
---
 .../org/javacs/debug/JavaDebugServer.java     | 151 +++++++++++++++---
 src/test/examples/debug/DeepVariables.class   | Bin 0 -> 844 bytes
 src/test/examples/debug/DeepVariables.java    |  14 ++
 .../java/org/javacs/JavaDebugServerTest.java  |  66 +++++++-
 4 files changed, 212 insertions(+), 19 deletions(-)
 create mode 100644 src/test/examples/debug/DeepVariables.class
 create mode 100644 src/test/examples/debug/DeepVariables.java

diff --git a/src/main/java/org/javacs/debug/JavaDebugServer.java b/src/main/java/org/javacs/debug/JavaDebugServer.java
index 53d36ce68..61dd3d04d 100644
--- a/src/main/java/org/javacs/debug/JavaDebugServer.java
+++ b/src/main/java/org/javacs/debug/JavaDebugServer.java
@@ -13,6 +13,7 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Objects;
@@ -440,6 +441,7 @@ public void terminate(TerminateArguments req) {
 
     @Override
     public void continue_(ContinueArguments req) {
+        valueIdTracker.clear();
         vm.resume();
     }
 
@@ -454,6 +456,7 @@ public void next(NextArguments req) {
         var step = vm.eventRequestManager().createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_OVER);
         step.addCountFilter(1);
         step.enable();
+        valueIdTracker.clear();
         vm.resume();
     }
 
@@ -468,6 +471,7 @@ public void stepIn(StepInArguments req) {
         var step = vm.eventRequestManager().createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_INTO);
         step.addCountFilter(1);
         step.enable();
+        valueIdTracker.clear();
         vm.resume();
     }
 
@@ -482,6 +486,7 @@ public void stepOut(StepOutArguments req) {
         var step = vm.eventRequestManager().createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_OUT);
         step.addCountFilter(1);
         step.enable();
+        valueIdTracker.clear();
         vm.resume();
     }
 
@@ -632,47 +637,157 @@ private com.sun.jdi.StackFrame findFrame(long id) {
     @Override
     public ScopesResponseBody scopes(ScopesArguments req) {
         var resp = new ScopesResponseBody();
+        var fields = new Scope();
+        fields.name = "Fields";
+        fields.presentationHint = "locals";
+        fields.expensive = true; // do not expand by default
+        fields.variablesReference = req.frameId * 2;
         var locals = new Scope();
         locals.name = "Locals";
         locals.presentationHint = "locals";
-        locals.variablesReference = req.frameId * 2;
-        var arguments = new Scope();
-        arguments.name = "Arguments";
-        arguments.presentationHint = "arguments";
-        arguments.variablesReference = req.frameId * 2 + 1;
-        resp.scopes = new Scope[] {locals, arguments};
+        locals.variablesReference = req.frameId * 2 + 1;
+        resp.scopes = new Scope[] {fields, locals};
         return resp;
     }
 
+    private static final long VALUE_ID_START = 1000000000;
+
+    private static class ValueIdTracker {
+        private final HashMap<Long, Value> values = new HashMap<>();
+        private long nextId = VALUE_ID_START;
+
+        public void clear() {
+            values.clear();
+            // Keep nextId to avoid accidentally accessing wrong Values.
+        }
+
+        public Value get(long id) {
+            return values.get(id);
+        }
+
+        public long put(Value value) {
+            long id = nextId++;
+            values.put(id, value);
+            return id;
+        }
+    }
+
+    private final ValueIdTracker valueIdTracker = new ValueIdTracker();
+
+    private static boolean hasInterestingChildren(Value value) {
+        return value instanceof ObjectReference && !(value instanceof StringReference);
+    }
+
     @Override
     public VariablesResponseBody variables(VariablesArguments req) {
-        var frameId = req.variablesReference / 2;
-        var scopeId = (int) (req.variablesReference % 2);
-        var argumentScope = scopeId == 1;
+        if (req.variablesReference < VALUE_ID_START) {
+            var frameId = req.variablesReference / 2;
+            var scopeId = (int)(req.variablesReference % 2);
+            return frameVariables(frameId, scopeId);
+        }
+        Value value = valueIdTracker.get(req.variablesReference);
+        return valueChildren(value);
+    }
+
+    private VariablesResponseBody frameVariables(long frameId, int scopeId) {
         var frame = findFrame(frameId);
+        var thread = frame.thread();
+        var variables = new ArrayList<Variable>();
+
+        if (scopeId == 0) {
+            var thisValue = frame.thisObject();
+            if (thisValue != null) {
+                variables.addAll(objectFieldsAsVariables(thisValue, thread));
+            }
+        } else {
+            variables.addAll(frameLocalsAsVariables(frame, thread));
+        }
+
+        var resp = new VariablesResponseBody();
+        resp.variables = variables.toArray(Variable[]::new);
+        return resp;
+    }
+
+    private VariablesResponseBody valueChildren(Value parentValue) {
+        // TODO: Use an actual owner thread.
+        ThreadReference mainThread = vm.allThreads().get(0);
+        var variables = new ArrayList<Variable>();
+
+        if (parentValue instanceof ArrayReference array) {
+            variables.addAll(arrayElementsAsVariables(array, mainThread));
+        } else if (parentValue instanceof ObjectReference object) {
+            variables.addAll(objectFieldsAsVariables(object, mainThread));
+        }
+
+        var resp = new VariablesResponseBody();
+        resp.variables = variables.toArray(Variable[]::new);
+        return resp;
+    }
+
+    private List<Variable> frameLocalsAsVariables(com.sun.jdi.StackFrame frame, ThreadReference thread) {
         List<LocalVariable> visible;
         try {
             visible = frame.visibleVariables();
         } catch (AbsentInformationException __) {
             LOG.warning(String.format("No visible variable information in %s", frame.location()));
-            return new VariablesResponseBody();
+            return List.of();
         }
-        var values = frame.getValues(visible);
-        var thread = frame.thread();
+
         var variables = new ArrayList<Variable>();
+        var values = frame.getValues(visible);
         for (var v : visible) {
-            if (v.isArgument() != argumentScope) continue;
+            var value = values.get(v);
             var w = new Variable();
             w.name = v.name();
-            w.value = print(values.get(v), thread);
+            w.value = print(value, thread);
             w.type = v.typeName();
-            // TODO set variablesReference and allow inspecting structure of collections and POJOs
+            if (hasInterestingChildren(value)) {
+                w.variablesReference = valueIdTracker.put(value);
+            }
+            if (value instanceof ArrayReference array) {
+                w.indexedVariables = array.length();
+            }
             // TODO set variablePresentationHint
             variables.add(w);
         }
-        var resp = new VariablesResponseBody();
-        resp.variables = variables.toArray(Variable[]::new);
-        return resp;
+        return variables;
+    }
+
+    private List<Variable> arrayElementsAsVariables(ArrayReference array, ThreadReference thread) {
+        var variables = new ArrayList<Variable>();
+        var arrayType = (ArrayType) array.type();
+        var values = array.getValues();
+        var length = values.size();
+        for (int i = 0; i < length; i++) {
+            var value = values.get(i);
+            var w = new Variable();
+            w.name = Integer.toString(i, 10);
+            w.value = print(value, thread);
+            w.type = arrayType.componentTypeName();
+            if (hasInterestingChildren(value)) {
+                w.variablesReference = valueIdTracker.put(value);
+            }
+            variables.add(w);
+        }
+        return variables;
+    }
+
+    private List<Variable> objectFieldsAsVariables(ObjectReference object, ThreadReference thread) {
+        var variables = new ArrayList<Variable>();
+        var classType = (ClassType) object.type();
+        var values = object.getValues(classType.allFields());
+        for (var field : values.keySet()) {
+            var value = values.get(field);
+            var w = new Variable();
+            w.name = field.name();
+            w.value = print(value, thread);
+            w.type = field.typeName();
+            if (hasInterestingChildren(value)) {
+                w.variablesReference = valueIdTracker.put(value);
+            }
+            variables.add(w);
+        }
+        return variables;
     }
 
     private String print(Value value, ThreadReference t) {
diff --git a/src/test/examples/debug/DeepVariables.class b/src/test/examples/debug/DeepVariables.class
new file mode 100644
index 0000000000000000000000000000000000000000..acb420536a0e27652924040bdf9a0655269e7310
GIT binary patch
literal 844
zcmZuv+iuf95Iq|wapE|aHYD6Hg;Jap8sG(?AYO`)DusXuN>%aXgjLwev5PNAd=@;k
zh)R3_AB8yU1R9IV^6bv+*)wNm_Sf$pKLI?!V+%PLCh|54C<-(V-Op~%bNyNG_2f`a
zV}ar`<*WF)fZ=q;CQ1U;7g8RL-B7s`Pev9@7}`{9*qXx#6W>HlpqasK?)kn9EmUEY
zv4(XMO&b@`$|N0qiDEe?N02aeYmmxOLGMkd{CE_H(w+A$T*M_4mu+0ZRe`k>lf=qf
zN{$3-q5PDnP!0osn0TJRmb0K*sjT1mKV;!LZkV`f;}$kpz&Ys!%p)zv^9AzGUT4f@
zH~1h0>I3D=VKSe{@SX0A!1^GVy58STEra>^qoTz6Ak&>bY38mXY1?_fB8)XFf7Vaa
zxZ#W!o97&JO2Kkmtt{`N>twe^K@v{oOO*=C<lfO`3RH$NieE{spK0uLT)UndMUrkI
zb+N%Y=lF5}0}P@_dz)U5tKeGbo<Mx%CWkw;`WXB-Y3&67cd<pUjC*hx(U+eRt#Or8
zm<J~)AHzDM&<|8+vyfk*si1={<J9?2!&@RXwtb2!Y3hS-Xl#E+d%w{=#<erX8ri@)
qO8i<BqQ$irH<#i{s9_uT$!_2QPjlE|g`fgHemvyPN_Qq6!TJLfgsVdU

literal 0
HcmV?d00001

diff --git a/src/test/examples/debug/DeepVariables.java b/src/test/examples/debug/DeepVariables.java
new file mode 100644
index 000000000..79f3623a1
--- /dev/null
+++ b/src/test/examples/debug/DeepVariables.java
@@ -0,0 +1,14 @@
+public class DeepVariables {
+    public static void main(String[] args) {
+        new DeepVariables().run();
+    }
+
+    public void run() {
+        Inner object = new Inner();
+        System.out.println(object.value);
+    }
+
+    private static class Inner {
+        public final int value = 42;
+    }
+}
diff --git a/src/test/java/org/javacs/JavaDebugServerTest.java b/src/test/java/org/javacs/JavaDebugServerTest.java
index 63fe72434..c3f9a5c08 100644
--- a/src/test/java/org/javacs/JavaDebugServerTest.java
+++ b/src/test/java/org/javacs/JavaDebugServerTest.java
@@ -1,5 +1,8 @@
 package org.javacs;
 
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+
 import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -207,7 +210,7 @@ public void printCollections() throws IOException, InterruptedException {
                 var scopes = server.scopes(requestScopes).scopes;
                 // Get locals
                 var requestLocals = new VariablesArguments();
-                requestLocals.variablesReference = scopes[0].variablesReference;
+                requestLocals.variablesReference = scopes[1].variablesReference;
                 var locals = server.variables(requestLocals).variables;
                 System.out.println("Locals:");
                 for (var v : locals) {
@@ -220,5 +223,66 @@ public void printCollections() throws IOException, InterruptedException {
         process.waitFor();
     }
 
+    @Test
+    public void deepVariables() throws IOException, InterruptedException {
+        launchProcess("DeepVariables");
+        attach(5005);
+        setBreakpoint("DeepVariables", 8);
+        server.configurationDone();
+        stoppedEvents.take();
+
+        // Find the main thread
+        org.javacs.debug.proto.Thread mainThread = null;
+        for (var t : server.threads().threads) {
+            if (t.name.equals("main")) {
+                mainThread = t;
+            }
+        }
+        assertThat(mainThread, notNullValue());
+
+        // Get the stack trace
+        var requestTrace = new StackTraceArguments();
+        requestTrace.threadId = mainThread.id;
+        var stack = server.stackTrace(requestTrace);
+
+        // Get variables
+        var requestScopes = new ScopesArguments();
+        requestScopes.frameId = stack.stackFrames[0].id;
+        var scopes = server.scopes(requestScopes).scopes;
+
+        // Get locals
+        var requestLocals = new VariablesArguments();
+        requestLocals.variablesReference = scopes[1].variablesReference;
+        var locals = server.variables(requestLocals).variables;
+
+        // Find an object value
+        Variable objectVariable = null;
+        for (var v : locals) {
+            if (v.name.equals("object")) {
+                objectVariable = v;
+            }
+        }
+        assertThat(objectVariable, notNullValue());
+
+        // Get an object field
+        var requestObject = new VariablesArguments();
+        requestObject.variablesReference = objectVariable.variablesReference;
+        var fields = server.variables(requestObject).variables;
+
+        // Inspect an object field
+        Variable fieldVariable = null;
+        for (var v : fields) {
+            if (v.name.equals("value")) {
+                fieldVariable = v;
+            }
+        }
+        assertThat(fieldVariable, notNullValue());
+        assertThat(fieldVariable.value, equalTo("42"));
+
+        // Wait for process to exit
+        server.continue_(new ContinueArguments());
+        process.waitFor();
+    }
+
     private static final Logger LOG = Logger.getLogger("main");
 }

From d8b271d5180aaf992f379e11ee047eb29970c1e0 Mon Sep 17 00:00:00 2001
From: Shuhei Takahashi <nya@google.com>
Date: Thu, 20 Mar 2025 01:07:13 +0900
Subject: [PATCH 2/2] Fix breakpoints in classes with inner/anonymous classes

Existing breakpoint installation logic assumes that there is one-to-one
correspondence between a class and a Java source file. But it does not
hold for classes with inner classes and/or anonymous classes.

This patch fixes the logic to handle the case. Also adds a regression
test.
---
 .../org/javacs/debug/JavaDebugServer.java     | 151 ++++++++++--------
 .../examples/debug/InnerClasses$Inner$1.class | Bin 0 -> 777 bytes
 .../examples/debug/InnerClasses$Inner.class   | Bin 0 -> 657 bytes
 src/test/examples/debug/InnerClasses.class    | Bin 0 -> 678 bytes
 src/test/examples/debug/InnerClasses.java     |  20 +++
 .../java/org/javacs/JavaDebugServerTest.java  |  53 ++++--
 6 files changed, 145 insertions(+), 79 deletions(-)
 create mode 100644 src/test/examples/debug/InnerClasses$Inner$1.class
 create mode 100644 src/test/examples/debug/InnerClasses$Inner.class
 create mode 100644 src/test/examples/debug/InnerClasses.class
 create mode 100644 src/test/examples/debug/InnerClasses.java

diff --git a/src/main/java/org/javacs/debug/JavaDebugServer.java b/src/main/java/org/javacs/debug/JavaDebugServer.java
index 61dd3d04d..ecf2ea4f6 100644
--- a/src/main/java/org/javacs/debug/JavaDebugServer.java
+++ b/src/main/java/org/javacs/debug/JavaDebugServer.java
@@ -7,6 +7,10 @@
 import com.sun.jdi.request.BreakpointRequest;
 import com.sun.jdi.request.EventRequest;
 import com.sun.jdi.request.StepRequest;
+
+import org.javacs.LogFormat;
+import org.javacs.debug.proto.*;
+
 import java.io.IOException;
 import java.net.ConnectException;
 import java.nio.file.Files;
@@ -19,8 +23,6 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.logging.*;
-import org.javacs.LogFormat;
-import org.javacs.debug.proto.*;
 
 public class JavaDebugServer implements DebugServer {
     public static void main(String[] args) { // TODO don't show references for main method
@@ -34,7 +36,9 @@ private static void createLogFile() {
         try {
             // TODO make location configurable
             var logFile =
-                    new FileHandler("/Users/georgefraser/Documents/java-language-server/java-debug-server.log", false);
+                    new FileHandler(
+                            "/Users/georgefraser/Documents/java-language-server/java-debug-server.log",
+                            false);
             logFile.setFormatter(new LogFormat());
             Logger.getLogger("").addHandler(logFile);
         } catch (IOException e) {
@@ -73,7 +77,11 @@ private void process(com.sun.jdi.event.Event event) {
             if (event instanceof ClassPrepareEvent) {
                 var prepare = (ClassPrepareEvent) event;
                 var type = prepare.referenceType();
-                LOG.info("ClassPrepareRequest for class " + type.name() + " in source " + relativePath(type));
+                LOG.info(
+                        "ClassPrepareRequest for class "
+                                + type.name()
+                                + " in source "
+                                + relativePath(type));
                 enablePendingBreakpointsIn(type);
                 vm.resume();
             } else if (event instanceof com.sun.jdi.event.BreakpointEvent) {
@@ -145,7 +153,10 @@ public SetBreakpointsResponseBody setBreakpoints(SetBreakpointsArguments req) {
     private void disableBreakpoints(Source source) {
         for (var b : vm.eventRequestManager().breakpointRequests()) {
             if (matchesFile(b, source)) {
-                LOG.info(String.format("Disable breakpoint %s:%d", source.path, b.location().lineNumber()));
+                LOG.info(
+                        String.format(
+                                "Disable breakpoint %s:%d",
+                                source.path, b.location().lineNumber()));
                 b.disable();
             }
         }
@@ -159,8 +170,9 @@ private Breakpoint enableBreakpoint(Source source, SourceBreakpoint b) {
             }
         }
         // Check for breakpoint in loaded classes
-        for (var type : loadedTypesMatching(source.path)) {
-            return enableBreakpointImmediately(source, b, type);
+        var enabled = enableBreakpointImmediately(source, b);
+        if (enabled != null) {
+            return enabled;
         }
         // If class hasn't been loaded, add breakpoint to pending list
         return enableBreakpointLater(source, b);
@@ -192,7 +204,10 @@ private List<ReferenceType> loadedTypesMatching(String absolutePath) {
     }
 
     private Breakpoint enableDisabledBreakpoint(Source source, BreakpointRequest b) {
-        LOG.info(String.format("Enable disabled breakpoint %s:%d", source.path, b.location().lineNumber()));
+        LOG.info(
+                String.format(
+                        "Enable disabled breakpoint %s:%d",
+                        source.path, b.location().lineNumber()));
         b.enable();
         var ok = new Breakpoint();
         ok.verified = true;
@@ -201,27 +216,20 @@ private Breakpoint enableDisabledBreakpoint(Source source, BreakpointRequest b)
         return ok;
     }
 
-    private Breakpoint enableBreakpointImmediately(Source source, SourceBreakpoint b, ReferenceType type) {
-        if (!tryEnableBreakpointImmediately(source, b, type)) {
-            var failed = new Breakpoint();
-            failed.verified = false;
-            failed.message = source.name + ":" + b.line + " could not be found or had no code on it";
-            return failed;
+    private Breakpoint enableBreakpointImmediately(Source source, SourceBreakpoint b) {
+        ArrayList<Location> locations = new ArrayList<>();
+        for (var type : loadedTypesMatching(source.path)) {
+            try {
+                locations.addAll(type.locationsOfLine(b.line));
+            } catch (AbsentInformationException __) {
+                LOG.info(
+                        String.format(
+                                "No locations in %s for breakpoint %s:%d",
+                                type.name(), source.path, b.line));
+            }
         }
-        var ok = new Breakpoint();
-        ok.verified = true;
-        ok.source = source;
-        ok.line = b.line;
-        return ok;
-    }
-
-    private boolean tryEnableBreakpointImmediately(Source source, SourceBreakpoint b, ReferenceType type) {
-        List<Location> locations;
-        try {
-            locations = type.locationsOfLine(b.line);
-        } catch (AbsentInformationException __) {
-            LOG.info(String.format("No locations in %s for breakpoint %s:%d", type.name(), source.path, b.line));
-            return false;
+        if (locations.isEmpty()) {
+            return null;
         }
         for (var l : locations) {
             LOG.info(String.format("Create breakpoint %s:%d", source.path, l.lineNumber()));
@@ -229,7 +237,11 @@ private boolean tryEnableBreakpointImmediately(Source source, SourceBreakpoint b
             req.setSuspendPolicy(EventRequest.SUSPEND_ALL);
             req.enable();
         }
-        return true;
+        var ok = new Breakpoint();
+        ok.verified = true;
+        ok.source = source;
+        ok.line = b.line;
+        return ok;
     }
 
     private Breakpoint enableBreakpointLater(Source source, SourceBreakpoint b) {
@@ -247,7 +259,8 @@ private Breakpoint enableBreakpointLater(Source source, SourceBreakpoint b) {
     }
 
     @Override
-    public SetFunctionBreakpointsResponseBody setFunctionBreakpoints(SetFunctionBreakpointsArguments req) {
+    public SetFunctionBreakpointsResponseBody setFunctionBreakpoints(
+            SetFunctionBreakpointsArguments req) {
         LOG.warning("Not yet implemented");
         return new SetFunctionBreakpointsResponseBody();
     }
@@ -297,7 +310,8 @@ private static AttachingConnector connector(String transport) {
             }
             found.add(conn.transport().name());
         }
-        throw new RuntimeException("Couldn't find connector for transport " + transport + " in " + found);
+        throw new RuntimeException(
+                "Couldn't find connector for transport " + transport + " in " + found);
     }
 
     @Override
@@ -369,48 +383,36 @@ private void enablePendingBreakpointsIn(ReferenceType type) {
         // Look for pending breakpoints that can be enabled
         var enabled = new ArrayList<Breakpoint>();
         for (var b : pendingBreakpoints) {
-            if (b.source.path.endsWith(path)) {
-                enablePendingBreakpoint(b, type);
+            if (b.source.path.endsWith(path) && enablePendingBreakpoint(b, type)) {
                 enabled.add(b);
             }
         }
         pendingBreakpoints.removeAll(enabled);
     }
 
-    private void enablePendingBreakpoint(Breakpoint b, ReferenceType type) {
+    private boolean enablePendingBreakpoint(Breakpoint b, ReferenceType type) {
+        List<Location> locations;
         try {
-            var locations = type.locationsOfLine(b.line);
-            for (var line : locations) {
-                var req = vm.eventRequestManager().createBreakpointRequest(line);
-                req.setSuspendPolicy(EventRequest.SUSPEND_ALL);
-                req.enable();
-            }
-            if (locations.isEmpty()) {
-                LOG.info("No locations at " + b.source.path + ":" + b.line);
-                var failed = new BreakpointEventBody();
-                failed.reason = "changed";
-                failed.breakpoint = b;
-                b.verified = false;
-                b.message = b.source.name + ":" + b.line + " could not be found or had no code on it";
-                client.breakpoint(failed);
-                return;
-            }
-            LOG.info("Enable breakpoint at " + b.source.path + ":" + b.line);
-            var ok = new BreakpointEventBody();
-            ok.reason = "changed";
-            ok.breakpoint = b;
-            b.verified = true;
-            b.message = null;
-            client.breakpoint(ok);
+            locations = type.locationsOfLine(b.line);
         } catch (AbsentInformationException __) {
-            LOG.info("Absent information at " + b.source.path + ":" + b.line);
-            var failed = new BreakpointEventBody();
-            failed.reason = "changed";
-            failed.breakpoint = b;
-            b.verified = false;
-            b.message = b.source.name + ":" + b.line + " could not be found or had no code on it";
-            client.breakpoint(failed);
+            return false;
+        }
+        if (locations.isEmpty()) {
+            return false;
         }
+        for (var line : locations) {
+            var req = vm.eventRequestManager().createBreakpointRequest(line);
+            req.setSuspendPolicy(EventRequest.SUSPEND_ALL);
+            req.enable();
+        }
+        LOG.info("Enable breakpoint at " + b.source.path + ":" + b.line);
+        var ok = new BreakpointEventBody();
+        ok.reason = "changed";
+        ok.breakpoint = b;
+        b.verified = true;
+        b.message = null;
+        client.breakpoint(ok);
+        return true;
     }
 
     private String relativePath(ReferenceType type) {
@@ -453,7 +455,9 @@ public void next(NextArguments req) {
             return;
         }
         LOG.info("Send StepRequest(STEP_LINE, STEP_OVER) to VM and resume");
-        var step = vm.eventRequestManager().createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_OVER);
+        var step =
+                vm.eventRequestManager()
+                        .createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_OVER);
         step.addCountFilter(1);
         step.enable();
         valueIdTracker.clear();
@@ -468,7 +472,9 @@ public void stepIn(StepInArguments req) {
             return;
         }
         LOG.info("Send StepRequest(STEP_LINE, STEP_INTO) to VM and resume");
-        var step = vm.eventRequestManager().createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_INTO);
+        var step =
+                vm.eventRequestManager()
+                        .createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_INTO);
         step.addCountFilter(1);
         step.enable();
         valueIdTracker.clear();
@@ -483,7 +489,9 @@ public void stepOut(StepOutArguments req) {
             return;
         }
         LOG.info("Send StepRequest(STEP_LINE, STEP_OUT) to VM and resume");
-        var step = vm.eventRequestManager().createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_OUT);
+        var step =
+                vm.eventRequestManager()
+                        .createStepRequest(thread, StepRequest.STEP_LINE, StepRequest.STEP_OUT);
         step.addCountFilter(1);
         step.enable();
         valueIdTracker.clear();
@@ -682,7 +690,7 @@ private static boolean hasInterestingChildren(Value value) {
     public VariablesResponseBody variables(VariablesArguments req) {
         if (req.variablesReference < VALUE_ID_START) {
             var frameId = req.variablesReference / 2;
-            var scopeId = (int)(req.variablesReference % 2);
+            var scopeId = (int) (req.variablesReference % 2);
             return frameVariables(frameId, scopeId);
         }
         Value value = valueIdTracker.get(req.variablesReference);
@@ -724,7 +732,8 @@ private VariablesResponseBody valueChildren(Value parentValue) {
         return resp;
     }
 
-    private List<Variable> frameLocalsAsVariables(com.sun.jdi.StackFrame frame, ThreadReference thread) {
+    private List<Variable> frameLocalsAsVariables(
+            com.sun.jdi.StackFrame frame, ThreadReference thread) {
         List<LocalVariable> visible;
         try {
             visible = frame.visibleVariables();
@@ -808,7 +817,9 @@ private String printObject(ObjectReference object, ThreadReference t) {
                 return string.value();
             } catch (InvocationException e) {
                 return String.format("toString() threw %s", e.exception().type().name());
-            } catch (InvalidTypeException | ClassNotLoadedException | IncompatibleThreadStateException e) {
+            } catch (InvalidTypeException
+                    | ClassNotLoadedException
+                    | IncompatibleThreadStateException e) {
                 throw new RuntimeException(e);
             }
         }
diff --git a/src/test/examples/debug/InnerClasses$Inner$1.class b/src/test/examples/debug/InnerClasses$Inner$1.class
new file mode 100644
index 0000000000000000000000000000000000000000..e9c9b6a1e20912a71566ba980c1e4207684a7340
GIT binary patch
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zkXY~lJQU)LQ`8`0$#dt<ocsBV@BI4x<0pUv^y(;~?85O;K~-S&wbm*<ie;9mtW_kf
zeSxaEh_co*?hpPK^gYy2cj5V1f-ewU$`7&^OMTvZJHAvC!}{luj?AGzIc$&WxQT{~
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zZsU%?%7Q`x_r1l$n&fbXE<BPO>GOVj<l>${^V<C14+w08i;mqM2{=c|nWCRTq}6dg
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zWYNp>E$CXmH1I-C;w0liW(XH;dYBi^n(3ouTU0w%nR%6D#>Jk1Kd%$06e%`&GingH
z3lRkNcJRWK_%7i-;{(nP8SRSK+4&05`40DUp?S!$%1Xc|1?)|s!XrFpMtwmO*y6lG
z*{6VF`r>G@2bA05`WM`2u6)DVHPtIf4f+ZSvMr(TitJ#USqV?@l+i(m4t9!_UF<P7
Oxffy=T{^Ii`1}DHzoNAO

literal 0
HcmV?d00001

diff --git a/src/test/examples/debug/InnerClasses$Inner.class b/src/test/examples/debug/InnerClasses$Inner.class
new file mode 100644
index 0000000000000000000000000000000000000000..2b6a3a862da3ed96d5f12c880b897d6a7146410c
GIT binary patch
literal 657
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literal 0
HcmV?d00001

diff --git a/src/test/examples/debug/InnerClasses.class b/src/test/examples/debug/InnerClasses.class
new file mode 100644
index 0000000000000000000000000000000000000000..6c042e927ab12c0102d85a1b70f3f18e88c9c389
GIT binary patch
literal 678
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diff --git a/src/test/examples/debug/InnerClasses.java b/src/test/examples/debug/InnerClasses.java
new file mode 100644
index 000000000..a7d441877
--- /dev/null
+++ b/src/test/examples/debug/InnerClasses.java
@@ -0,0 +1,20 @@
+public class InnerClasses {
+    public static void main(String[] args) {
+        System.out.println("at main");
+        new Inner().run();
+    }
+
+    // An inner class:
+    private static class Inner {
+        public void run() {
+            System.out.println("at Inner.run");
+            // An anonymous class:
+            new Runnable() {
+                @Override
+                public void run() {
+                    System.out.println("at Runnable.run");
+                }
+            }.run();
+        }
+    }
+}
diff --git a/src/test/java/org/javacs/JavaDebugServerTest.java b/src/test/java/org/javacs/JavaDebugServerTest.java
index c3f9a5c08..36c6ea4af 100644
--- a/src/test/java/org/javacs/JavaDebugServerTest.java
+++ b/src/test/java/org/javacs/JavaDebugServerTest.java
@@ -3,15 +3,16 @@
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
+import org.javacs.debug.*;
+import org.javacs.debug.proto.*;
+import org.junit.Test;
+
 import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.List;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.logging.Logger;
-import org.javacs.debug.*;
-import org.javacs.debug.proto.*;
-import org.junit.Test;
 
 public class JavaDebugServerTest {
     Path workingDirectory = Paths.get("src/test/examples/debug");
@@ -45,12 +46,15 @@ public void breakpoint(BreakpointEventBody evt) {
             if (evt.breakpoint.verified) {
                 LOG.info(
                         String.format(
-                                "Breakpoint at %s:%d is verified", evt.breakpoint.source.path, evt.breakpoint.line));
+                                "Breakpoint at %s:%d is verified",
+                                evt.breakpoint.source.path, evt.breakpoint.line));
             } else {
                 LOG.info(
                         String.format(
                                 "Breakpoint at %s:%d cannot be verified because %s",
-                                evt.breakpoint.source.path, evt.breakpoint.line, evt.breakpoint.message));
+                                evt.breakpoint.source.path,
+                                evt.breakpoint.line,
+                                evt.breakpoint.message));
             }
         }
 
@@ -62,9 +66,18 @@ public RunInTerminalResponseBody runInTerminal(RunInTerminalRequest req) {
 
     public void launchProcess(String mainClass) throws IOException, InterruptedException {
         var command =
-                List.of("java", "-Xdebug", "-Xrunjdwp:transport=dt_socket,address=5005,server=y,suspend=y", mainClass);
+                List.of(
+                        "java",
+                        "-Xdebug",
+                        "-Xrunjdwp:transport=dt_socket,address=5005,server=y,suspend=y",
+                        mainClass);
         LOG.info("Launch " + String.join(", ", command));
-        process = new ProcessBuilder().command(command).directory(workingDirectory.toFile()).inheritIO().start();
+        process =
+                new ProcessBuilder()
+                        .command(command)
+                        .directory(workingDirectory.toFile())
+                        .inheritIO()
+                        .start();
         java.lang.Thread.sleep(1000);
     }
 
@@ -112,7 +125,9 @@ public void setBreakpoint() throws IOException, InterruptedException {
                 var stack = server.stackTrace(requestTrace);
                 System.out.println("Thread main:");
                 for (var frame : stack.stackFrames) {
-                    System.out.println(String.format("\t%s:%d (%s)", frame.name, frame.line, frame.source.path));
+                    System.out.println(
+                            String.format(
+                                    "\t%s:%d (%s)", frame.name, frame.line, frame.source.path));
                 }
                 // Get variables
                 var requestScopes = new ScopesArguments();
@@ -202,7 +217,9 @@ public void printCollections() throws IOException, InterruptedException {
                 var stack = server.stackTrace(requestTrace);
                 System.out.println("Thread main:");
                 for (var frame : stack.stackFrames) {
-                    System.out.println(String.format("\t%s:%d (%s)", frame.name, frame.line, frame.source.path));
+                    System.out.println(
+                            String.format(
+                                    "\t%s:%d (%s)", frame.name, frame.line, frame.source.path));
                 }
                 // Get variables
                 var requestScopes = new ScopesArguments();
@@ -284,5 +301,23 @@ public void deepVariables() throws IOException, InterruptedException {
         process.waitFor();
     }
 
+    @Test
+    public void setBreakpointInnerClasses() throws IOException, InterruptedException {
+        launchProcess("InnerClasses");
+        // Attach to the process
+        attach(5005);
+        // Set breakpoints
+        setBreakpoint("InnerClasses", 3); // at main
+        setBreakpoint("InnerClasses", 10); // at Inner.run
+        setBreakpoint("InnerClasses", 15); // at Runnable.run
+        server.configurationDone();
+        // Should stop 3 times
+        for (int i = 0; i < 3; i++) {
+            stoppedEvents.take();
+            server.continue_(new ContinueArguments());
+        }
+        process.waitFor();
+    }
+
     private static final Logger LOG = Logger.getLogger("main");
 }