Simplify Arrays.asList with new array argument (#633)

* Simplify `Arrays.asList` with a single array argument

* Minimize implementation

* Skip edge case

Author: timtebeek

.claude/settings.local.json

@@ -2,11 +2,13 @@
   "permissions": {
     "allow": [
       "Bash(./gradlew:*)",
+      "Bash(cat:*)",
       "Bash(echo:*)",
       "Bash(find:*)",
       "Bash(gh:*)",
       "Bash(git:*)",
       "Bash(grep:*)",
+      "Bash(javac:*)",
       "Bash(mv:*)",
       "Bash(npm test:*)",
       "Bash(rg:*)",
@@ -27,9 +29,8 @@
       "mcp__idea__open_file_in_editor",
       "mcp__idea__replace_selected_text",
       "mcp__idea__replace_specific_text",
-      "mcp__idea__search_in_files_content",
-      "Bash(./gradlew compileTestJava:*)"
+      "mcp__idea__search_in_files_content"
     ],
     "deny": []
   }
-}
+}

src/main/java/org/openrewrite/staticanalysis/SimplifyArraysAsList.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2024 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.openrewrite.ExecutionContext;
+import org.openrewrite.Preconditions;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.java.JavaVisitor;
+import org.openrewrite.java.MethodMatcher;
+import org.openrewrite.java.search.UsesMethod;
+import org.openrewrite.java.tree.Expression;
+import org.openrewrite.java.tree.J;
+
+import java.time.Duration;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+public class SimplifyArraysAsList extends Recipe {
+    private static final MethodMatcher ARRAYS_AS_LIST = new MethodMatcher("java.util.Arrays asList(..)");
+
+    @Override
+    public String getDisplayName() {
+        return "Simplify `Arrays.asList(..)` with varargs";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Simplifies `Arrays.asList()` method calls that use explicit array creation to use varargs instead. " +
+                "For example, `Arrays.asList(new String[]{\"a\", \"b\", \"c\"})` becomes `Arrays.asList(\"a\", \"b\", \"c\")`.";
+    }
+
+    @Override
+    public Set<String> getTags() {
+        return Collections.singleton("RSPEC-S3878");
+    }
+
+    @Override
+    public Duration getEstimatedEffortPerOccurrence() {
+        return Duration.ofMinutes(2);
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        return Preconditions.check(new UsesMethod<>(ARRAYS_AS_LIST), new JavaVisitor<ExecutionContext>() {
+            @Override
+            public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
+                J.MethodInvocation mi = (J.MethodInvocation) super.visitMethodInvocation(method, ctx);
+                if (ARRAYS_AS_LIST.matches(mi) && mi.getArguments().size() == 1 &&
+                        mi.getArguments().get(0) instanceof J.NewArray) {
+                    J.NewArray newArray = (J.NewArray) mi.getArguments().get(0);
+                    List<Expression> elements = newArray.getInitializer();
+                    if (newArray.getDimensions().size() == 1 && elements != null &&
+                            // Skip transformation if there's exactly one null element to avoid ambiguity
+                            (elements.size() != 1 || !J.Literal.isLiteralValue(elements.get(0), null))) {
+                        return mi.withArguments(newArray.getInitializer());
+                    }
+                }
+                return mi;
+            }
+        });
+    }
+}

src/main/resources/META-INF/rewrite/common-static-analysis.yml

@@ -78,6 +78,7 @@ recipeList:
   - org.openrewrite.staticanalysis.ReplaceClassIsInstanceWithInstanceof
   - org.openrewrite.staticanalysis.ReplaceLambdaWithMethodReference
   - org.openrewrite.staticanalysis.ReplaceStringBuilderWithString
+  - org.openrewrite.staticanalysis.SimplifyArraysAsList
   - org.openrewrite.staticanalysis.SimplifyBooleanExpression
   - org.openrewrite.staticanalysis.SimplifyBooleanReturn
 #  - org.openrewrite.staticanalysis.SimplifyTernaryRecipes