CastArraysAsListToList Recipe (#366)

* Add CastArraysAsListToList Recipe

* Minor polish: UsesMethod, update display name, unused imports

---------

Co-authored-by: Tim te Beek <[email protected]>

src/main/java/org/openrewrite/java/migrate/CastArraysAsListToList.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2023 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (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://www.apache.org/licenses/LICENSE-2.0
+ * <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.java.migrate;
+
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.Preconditions;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.java.JavaTemplate;
+import org.openrewrite.java.JavaVisitor;
+import org.openrewrite.java.MethodMatcher;
+import org.openrewrite.java.search.UsesMethod;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.JavaType;
+
+public class CastArraysAsListToList extends Recipe {
+
+    @Override
+    public String getDisplayName() {
+        return "Remove explicit casts on `Arrays.asList(..).toArray()`";
+    }
+
+    @Override
+    public String getDescription() {
+        //language=markdown
+        return "Convert code like `(Integer[]) Arrays.asList(1, 2, 3).toArray()` to `Arrays.asList(1, 2, 3).toArray(new Integer[0])`.";
+    }
+
+    private static final MethodMatcher ARRAYS_AS_LIST = new MethodMatcher("java.util.Arrays asList(..)", false);
+    private static final MethodMatcher LIST_TO_ARRAY = new MethodMatcher("java.util.List toArray()", true);
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        return Preconditions.check(
+                Preconditions.and(new UsesMethod<>(ARRAYS_AS_LIST), new UsesMethod<>(LIST_TO_ARRAY)),
+                new CastArraysAsListToListVisitor());
+    }
+
+    private static class CastArraysAsListToListVisitor extends JavaVisitor<ExecutionContext> {
+        @Override
+        public J visitTypeCast(J.TypeCast typeCast, ExecutionContext executionContext) {
+            J j = super.visitTypeCast(typeCast, executionContext);
+            if (!(j instanceof J.TypeCast)) {
+                return j;
+            }
+            typeCast = (J.TypeCast) j;
+
+            boolean matches = typeCast.getClazz().getTree() instanceof J.ArrayType
+                              && (typeCast.getType() instanceof JavaType.Class || typeCast.getType() instanceof JavaType.Parameterized)
+                              && ((JavaType.FullyQualified) typeCast.getType()).getOwningClass() == null // does not support inner class now
+                              && LIST_TO_ARRAY.matches(typeCast.getExpression())
+                              && typeCast.getExpression() instanceof J.MethodInvocation
+                              && ARRAYS_AS_LIST.matches(((J.MethodInvocation) typeCast.getExpression()).getSelect());
+            if (!matches) {
+                return typeCast;
+            }
+
+            String fullyQualifiedName = ((JavaType.FullyQualified) typeCast.getType()).getFullyQualifiedName();
+            int dimensionSize = ((J.ArrayType) typeCast.getClazz().getTree()).getDimensions().size();
+
+            if (fullyQualifiedName.equals("java.lang.Object") && dimensionSize == 1) {
+                // we don't need to fix this case because toArray() does return Object[] type
+                return typeCast;
+            }
+
+            // we don't add generic type name here because generic array creation is not allowed
+            StringBuilder newArrayString = new StringBuilder();
+            String className = fullyQualifiedName.substring(fullyQualifiedName.lastIndexOf(".") + 1);
+            newArrayString.append(className);
+            newArrayString.append("[0]");
+            for (int i = 0; i < dimensionSize - 1; i++) {
+                newArrayString.append("[]");
+            }
+
+            JavaTemplate t = JavaTemplate
+                    .builder("#{any(java.util.List)}.toArray(new " + newArrayString + ")")
+                    .imports(fullyQualifiedName)
+                    .build();
+            return t.apply(updateCursor(typeCast), typeCast.getCoordinates().replace(), ((J.MethodInvocation) typeCast.getExpression()).getSelect());
+        }
+    }
+}

src/main/resources/META-INF/rewrite/java-version-11.yml

@@ -32,6 +32,7 @@ tags:
 recipeList:
   - org.openrewrite.java.migrate.UpgradeToJava8
   - org.openrewrite.java.migrate.UseJavaUtilBase64
+  - org.openrewrite.java.migrate.CastArraysAsListToList
   # Add an explicit JAXB/JAX-WS runtime and upgrade the dependencies to Jakarta EE 8
   - org.openrewrite.java.migrate.javax.AddJaxbDependencies
   - org.openrewrite.java.migrate.javax.AddJaxwsDependencies

src/test/java/org/openrewrite/java/migrate/CastArraysAsListToListTest.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2023 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (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://www.apache.org/licenses/LICENSE-2.0
+ * <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.java.migrate;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class CastArraysAsListToListTest implements RewriteTest {
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec.recipe(new CastArraysAsListToList());
+    }
+
+    @Test
+    void positiveCases() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              import java.util.Arrays;
+              
+              class Foo {
+                  void bar() {
+                      Integer[] array1 = (Integer[]) Arrays.asList(1, 2, 3).toArray();
+                      Integer[][] array2 = (Integer[][]) Arrays.asList(new Integer[]{1}, new Integer[]{2}).toArray();
+                      Object[][] array3 = (Object[][]) Arrays.asList(new Object[]{}, new Object[]{}).toArray();
+                  }
+              }
+              """,
+            """
+              import java.util.Arrays;
+              
+              class Foo {
+                  void bar() {
+                      Integer[] array1 = Arrays.asList(1, 2, 3).toArray(new Integer[0]);
+                      Integer[][] array2 = Arrays.asList(new Integer[]{1}, new Integer[]{2}).toArray(new Integer[0][]);
+                      Object[][] array3 = Arrays.asList(new Object[]{}, new Object[]{}).toArray(new Object[0][]);
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void negativeCases() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              import java.util.Arrays;
+              import java.util.Collections;
+              
+              class Foo {
+                  void bar() {
+                      Object[] array1 = (Object[]) Arrays.asList("a","b").toArray();
+                      Integer[] array2 = (Integer[]) Collections.singletonList(1).toArray();
+                      Integer[] array3 = Arrays.asList(1, 2, 3).toArray(new Integer[0]);
+                  }
+              }
+              """
+          )
+        );
+    }
+}