Default formatter for Exception objects #125

This commit modifies the default detail formatter of Exception objects
by showing Exception class name and its stack trace by default if no
specific detail formatter configured for Exception objects

Fixes : #125

org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/AbstractDebugTest.java

@@ -409,6 +409,7 @@ void assert15Project() {
 				cfgs.add(createLaunchConfiguration(jp, "a.b.c.GenericMethodEntryTest"));
 				cfgs.add(createLaunchConfiguration(jp, "org.eclipse.debug.tests.targets.HcrClass", true));
 				cfgs.add(createLaunchConfiguration(jp, "a.b.c.Bug570988"));
+				cfgs.add(createLaunchConfiguration(jp, "a.b.c.ExceptionDefaultTest"));
 				loaded15 = true;
 				waitForBuild();
 	        }

org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/variables/DetailFormatterTests.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) Mar 12, 2016 IBM Corporation and others.
+ * Copyright (c) 2016, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -467,4 +467,51 @@ public void testFormatterForPrimitivesCharArray() throws Exception {
 		}
 	}
 
+	public void testFormatterForExceptionObjectsWithoutFormatter() throws Exception {
+		IJavaThread thread = null;
+		JavaDetailFormattersManager jdfm = JavaDetailFormattersManager.getDefault();
+		try {
+			String typename = "a.b.c.ExceptionDefaultTest";
+			createLineBreakpoint(19, typename);
+			thread = launchToBreakpoint(typename);
+			assertNotNull("The program did not suspend", thread);
+			IJavaVariable var = thread.findVariable("e");
+			assertNotNull("the variable 'e' must exist in the frame", var);
+			jdfm.computeValueDetail((IJavaValue) var.getValue(), thread, fListener);
+			waitForListenerValue();
+			assertNotNull("The IValue of the detailComputed callback cannot be null", fListener.value);
+			String value = fListener.result.toString().trim();
+			value = value.split("\n")[2];
+			assertEquals("a.b.c.ExceptionDefaultTest.main(ExceptionDefaultTest.java:18)", value);
+		} finally {
+			terminateAndRemove(thread);
+			removeAllBreakpoints();
+		}
+	}
+
+	public void testFormatterForExceptionObjectsWithFormatter() throws Exception {
+		IJavaThread thread = null;
+		DetailFormatter formatter = null;
+		JavaDetailFormattersManager jdfm = JavaDetailFormattersManager.getDefault();
+		try {
+			String typename = "a.b.c.ExceptionDefaultTest";
+			createLineBreakpoint(19, typename);
+			thread = launchToBreakpoint(typename);
+			assertNotNull("The program did not suspend", thread);
+			String snippet = "this.toString()";
+			formatter = new DetailFormatter("java.lang.Exception", snippet, true);
+			jdfm.setAssociatedDetailFormatter(formatter);
+			IJavaVariable var2 = thread.findVariable("e");
+			assertNotNull("the variable 'e' must exist in the frame", var2);
+			jdfm.computeValueDetail((IJavaValue) var2.getValue(), thread, fListener);
+			waitForListenerValue();
+			assertNotNull("The IValue of the detailComputed callback cannot be null", fListener.value);
+			assertEquals("java.lang.Exception", fListener.result.toString());
+		} finally {
+			jdfm.removeAssociatedDetailFormatter(formatter);
+			terminateAndRemove(thread);
+			removeAllBreakpoints();
+		}
+	}
+
 }

org.eclipse.jdt.debug.tests/testsource-j2se-1.5/a/b/c/ExceptionDefaultTest.java

@@ -0,0 +1,21 @@
+/*******************************************************************************
+ * Copyright (c) 2025 IBM Corporation and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package a.b.c;
+
+public class ExceptionDefaultTest {
+	public static void main(String[] args) {
+		Exception e = new Exception();
+		int p=10;
+	}
+}

org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/JavaDetailFormattersManager.java

@@ -382,6 +382,7 @@ private String getDetailFormatter(JDIType type) throws DebugException {
 	 * @return the snippet for the given class / super class
 	 * @throws DebugException if there is a problem computing the snippet
 	 */
+	@SuppressWarnings("nls")
 	private String getDetailFormatterSuperClass(IJavaClassType type) throws DebugException {
 		if (type == null) {
 			return null;
@@ -390,6 +391,17 @@ private String getDetailFormatterSuperClass(IJavaClassType type) throws DebugExc
 		if (detailFormatter != null && detailFormatter.isEnabled()) {
 			return detailFormatter.getSnippet();
 		}
+		if ((detailFormatter == null || !detailFormatter.isEnabled()) && type.getName().equals("java.lang.Throwable")) {
+			String snippet = """
+					StringBuilder stackTrace = new StringBuilder();
+					stackTrace.append(this.getClass().getName()+\" \\n\\n\");
+					for (StackTraceElement element : this.getStackTrace()) {
+						stackTrace.append(element.toString()+\" \\n\");
+					}
+					return stackTrace.toString();
+					""";
+			return snippet;
+		}
 		return getDetailFormatterSuperClass(type.getSuperclass());
 	}