openrewrite
diff --git a/‎src/main/java/org/openrewrite/staticanalysis/OnlyCatchDeclaredExceptions.java‎
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+/*
+ * Copyright 2025 the original author or authors.
+ * <p>
+ * Licensed under the Moderne Source Available License (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://docs.moderne.io/licensing/moderne-source-available-license
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.staticanalysis;
+
+import org.jspecify.annotations.Nullable;
+import org.openrewrite.*;
+import org.openrewrite.internal.ListUtils;
+import org.openrewrite.java.JavaIsoVisitor;
+import org.openrewrite.java.JavaTemplate;
+import org.openrewrite.java.search.UsesType;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.JavaType;
+import org.openrewrite.java.tree.JavaType.FullyQualified;
+import org.openrewrite.java.tree.TypeUtils;
+
+import java.util.*;
+
+import static java.util.stream.Collectors.joining;
+import static java.util.stream.Collectors.toList;
+
+public class OnlyCatchDeclaredExceptions extends Recipe {
+
+    private static final String JAVA_LANG_EXCEPTION = "java.lang.Exception";
+
+    @Override
+    public String getDisplayName() {
+        return "Replace `catch(Exception)` with specific declared exceptions thrown in the try block";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Replaces `catch(Exception e)` blocks with a multi-catch block " +
+                "(`catch (SpecificException1 | SpecificException2 e)`) containing only the exceptions declared " +
+                "thrown by method or constructor invocations within the `try` block that are not already caught " +
+                "by more specific `catch` clauses.";
+    }
+
+    @Override
+    public Set<String> getTags() {
+        return new HashSet<>(Arrays.asList("CWE-396", "RSPEC-S2221"));
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        JavaIsoVisitor<ExecutionContext> visitor = new JavaIsoVisitor<ExecutionContext>() {
+            @Override
+            public J.Try visitTry(J.Try aTry, ExecutionContext ctx) {
+                J.Try t = super.visitTry(aTry, ctx);
+                return t.withCatches(ListUtils.map(t.getCatches(), c -> {
+                    if (isGenericCatch(c)) {
+                        // Find declared thrown exceptions that are not already specifically caught
+                        Set<JavaType> declaredThrown = getDeclaredThrownExceptions(t);
+                        declaredThrown.removeAll(getCaughtExceptions(t));
+                        if (!declaredThrown.isEmpty()) {
+                            return multiCatchWithDeclaredExceptions(c, declaredThrown);
+                        }
+                    }
+                    return c;
+                }));
+            }
+
+            private boolean isGenericCatch(J.Try.Catch aCatch) {
+                FullyQualified fq = TypeUtils.asFullyQualified(aCatch.getParameter().getType());
+                if (fq != null) {
+                    String fqn = fq.getFullyQualifiedName();
+                    return TypeUtils.fullyQualifiedNamesAreEqual(JAVA_LANG_EXCEPTION, fqn);
+                }
+                return false;
+            }
+
+            private Set<JavaType> getCaughtExceptions(J.Try aTry) {
+                Set<JavaType> caughtExceptions = new HashSet<>();
+                for (J.Try.Catch c : aTry.getCatches()) {
+                    JavaType type = c.getParameter().getType();
+                    if (type instanceof JavaType.MultiCatch) {
+                        caughtExceptions.addAll(((JavaType.MultiCatch) type).getThrowableTypes());
+                    } else if (type != null) {
+                        caughtExceptions.add(type);
+                    }
+                }
+                return caughtExceptions;
+            }
+
+            private Set<JavaType> getDeclaredThrownExceptions(J.Try aTry) {
+                return new JavaIsoVisitor<Set<JavaType>>() {
+                    @Override
+                    public @Nullable JavaType visitType(@Nullable JavaType javaType, Set<JavaType> javaTypes) {
+                        if (javaType instanceof JavaType.Method) {
+                            javaTypes.addAll(((JavaType.Method) javaType).getThrownExceptions());
+                        }
+                        return super.visitType(javaType, javaTypes);
+                    }
+                }.reduce(aTry.getBody(), new HashSet<>());
+            }
+
+            private J.Try.Catch multiCatchWithDeclaredExceptions(J.Try.Catch aCatch, Set<JavaType> thrownExceptions) {
+                List<FullyQualified> fqs = thrownExceptions.stream()
+                        .map(TypeUtils::asFullyQualified)
+                        .filter(Objects::nonNull)
+                        .sorted(Comparator.comparing(FullyQualified::getClassName))
+                        .collect(toList());
+                String throwableTypes = fqs
+                        .stream()
+                        .map(FullyQualified::getClassName)
+                        .collect(joining("|"));
+                String[] imports = fqs.stream().map(FullyQualified::getFullyQualifiedName).toArray(String[]::new);
+                for (String s : imports) {
+                    maybeAddImport(s, false);
+                }
+
+                J.Try surroundingTry = getCursor().firstEnclosing(J.Try.class);
+                assert surroundingTry != null;
+
+                // Preserve the existing variable name from the original generic catch block
+                String variableName = aCatch.getParameter().getTree().getVariables().get(0).getSimpleName();
+                J.Try generatedTry = JavaTemplate.builder(String.format("try {} catch (%s %s) {}", throwableTypes, variableName))
+                        .imports(imports)
+                        .build()
+                        .apply(new Cursor(getCursor(), surroundingTry), surroundingTry.getCoordinates().replace());
+                return aCatch.withParameter(generatedTry.getCatches().get(0).getParameter());
+            }
+        };
+        return Preconditions.check(new UsesType<>(JAVA_LANG_EXCEPTION, false), visitor);
+    }
+}