Modernize collections

org.openrewrite.staticanalysis.ModernizeCollections

Replace the legacy synchronized types Hashtable, Vector, Stack, and StringBuffer with their modern unsynchronized counterparts HashMap, ArrayList, Deque/ArrayDeque, and StringBuilder. Each replacement is only applied when data flow analysis can prove the instance is a local variable that never escapes its method, so the synchronization it provided is redundant.

Tags

• RSPEC-S1149

Recipe source

GitHub: static-analysis.yml, Issue Tracker, Maven Central

info

This recipe is composed of more than one recipe. If you want to customize the set of recipes this is composed of, you can find and copy the GitHub source for the recipe from the link above.

This recipe is available under the Moderne Source Available License.

Definition

Recipe List

• Replace java.util.Hashtable with java.util.HashMap
• Replace java.util.Vector with java.util.ArrayList
• Replace java.util.Stack with java.util.Deque
• Replace java.lang.StringBuffer with java.lang.StringBuilder

Yaml Recipe List

---
type: specs.openrewrite.org/v1beta/recipe
name: org.openrewrite.staticanalysis.ModernizeCollections
displayName: Modernize collections
description: |
  Replace the legacy synchronized types `Hashtable`, `Vector`, `Stack`, and `StringBuffer` with their modern unsynchronized counterparts `HashMap`, `ArrayList`, `Deque`/`ArrayDeque`, and `StringBuilder`. Each replacement is only applied when data flow analysis can prove the instance is a local variable that never escapes its method, so the synchronization it provided is redundant.
tags:
  - RSPEC-S1149
recipeList:
  - org.openrewrite.staticanalysis.ReplaceHashtableWithHashMap
  - org.openrewrite.staticanalysis.ReplaceVectorWithArrayList
  - org.openrewrite.staticanalysis.ReplaceStackWithDeque
  - org.openrewrite.staticanalysis.ReplaceStringBufferWithStringBuilder

Usage

This recipe has no required configuration options. It can be activated by adding a dependency on `org.openrewrite.recipe:rewrite-static-analysis` in your build file or by running a shell command (in which case no build changes are needed):

Gradle

1. Add the following to your build.gradle file:
   build.gradle

   plugins {
       id("org.openrewrite.rewrite") version("latest.release")
   }
   
   rewrite {
       activeRecipe("org.openrewrite.staticanalysis.ModernizeCollections")
       setExportDatatables(true)
   }
   
   repositories {
       mavenCentral()
   }
   
   dependencies {
       rewrite("org.openrewrite.recipe:rewrite-static-analysis:2.40.0")
   }

2. Run gradle rewriteRun to run the recipe.

Gradle init script

1. Create a file named init.gradle in the root of your project.
   init.gradle

   initscript {
       repositories {
           maven { url "https://plugins.gradle.org/m2" }
       }
       dependencies { classpath("org.openrewrite:plugin:7.37.0") }
   }
   rootProject {
       plugins.apply(org.openrewrite.gradle.RewritePlugin)
       dependencies {
           rewrite("org.openrewrite.recipe:rewrite-static-analysis:2.40.0")
       }
       rewrite {
           activeRecipe("org.openrewrite.staticanalysis.ModernizeCollections")
       setExportDatatables(true)
       }
       afterEvaluate {
           if (repositories.isEmpty()) {
               repositories {
                   mavenCentral()
               }
           }
       }
   }

2. Run the recipe.
   shell

   gradle --init-script init.gradle rewriteRun

Gradle init script (Kotlin)

1. Create a file named init.gradle.kts in the root of your project.
   init.gradle.kts

   initscript {
       repositories {
           maven { url = uri("https://plugins.gradle.org/m2") }
       }
       dependencies { classpath("org.openrewrite:plugin:7.37.0") }
   }
   rootProject {
       plugins.apply(org.openrewrite.gradle.RewritePlugin::class.java)
       dependencies {
           add("rewrite", "org.openrewrite.recipe:rewrite-static-analysis:2.40.0")
       }
       extensions.configure<org.openrewrite.gradle.RewriteExtension> {
           activeRecipe("org.openrewrite.staticanalysis.ModernizeCollections")
       setExportDatatables(true)
       }
       afterEvaluate {
           if (repositories.isEmpty()) {
               repositories {
                   mavenCentral()
               }
           }
       }
   }

2. Run the recipe.
   shell

   gradle --init-script init.gradle.kts rewriteRun

Maven POM

1. Add the following to your pom.xml file:
   pom.xml

   <project>
     <build>
       <plugins>
         <plugin>
           <groupId>org.openrewrite.maven</groupId>
           <artifactId>rewrite-maven-plugin</artifactId>
           <version>6.44.0</version>
           <configuration>
             <exportDatatables>true</exportDatatables>
             <activeRecipes>
               <recipe>org.openrewrite.staticanalysis.ModernizeCollections</recipe>
             </activeRecipes>
           </configuration>
           <dependencies>
             <dependency>
               <groupId>org.openrewrite.recipe</groupId>
               <artifactId>rewrite-static-analysis</artifactId>
               <version>2.40.0</version>
             </dependency>
           </dependencies>
         </plugin>
       </plugins>
     </build>
   </project>

2. Run mvn rewrite:run to run the recipe.

Maven Command Line

You will need to have Maven installed on your machine before you can run the following command.

shell

mvn -U org.openrewrite.maven:rewrite-maven-plugin:run --define rewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-static-analysis:RELEASE --define rewrite.activeRecipes=org.openrewrite.staticanalysis.ModernizeCollections --define rewrite.exportDatatables=true

Moderne CLI

You will need to have configured the Moderne CLI on your machine before you can run the following command.

shell

mod run . --recipe ModernizeCollections

If the recipe is not available locally, then you can install it using:

mod config recipes jar install org.openrewrite.recipe:rewrite-static-analysis:2.40.0

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Data Tables

LegacySynchronizedTypesNotMigrated

Legacy synchronized types not migrated

org.openrewrite.staticanalysis.table.LegacySynchronizedTypesNotMigrated

Instances of a legacy synchronized type (Hashtable, Vector, Stack, StringBuffer) that were found but left unchanged because they could not be proven safe to modernize.

Column Name	Description
Source path	The path to the source file containing the unmigrated reference.
Class	The fully qualified name of the class containing the reference.
Unmigrated type	The fully qualified name of the legacy synchronized type that was found but not migrated.
Reason	Why the instance was left unchanged.

SourcesFileResults

Source files that had results

org.openrewrite.table.SourcesFileResults

Source files that were modified by the recipe run.

Column Name	Description
Source path before the run	The source path of the file before the run. null when a source file was created during the run.
Source path after the run	A recipe may modify the source path. This is the path after the run. null when a source file was deleted during the run.
Parent of the recipe that made changes	In a hierarchical recipe, the parent of the recipe that made a change. Empty if this is the root of a hierarchy or if the recipe is not hierarchical at all.
Recipe that made changes	The specific recipe that made a change.
Estimated time saving	An estimated effort that a developer to fix manually instead of using this recipe, in unit of seconds.
Cycle	The recipe cycle in which the change was made.

SearchResults

Source files that had search results

org.openrewrite.table.SearchResults

Search results that were found during the recipe run.

Column Name	Description
Source path of search result before the run	The source path of the file with the search result markers present.
Source path of search result after run the run	A recipe may modify the source path. This is the path after the run. null when a source file was deleted during the run.
Result	The trimmed printed tree of the LST element that the marker is attached to.
Description	The content of the description of the marker.
Recipe that added the search marker	The specific recipe that added the Search marker.

SourcesFileErrors

Source files that errored on a recipe

org.openrewrite.table.SourcesFileErrors

The details of all errors produced by a recipe run.

Column Name	Description
Source path	The file that failed to parse.
Recipe that made changes	The specific recipe that made a change.
Stack trace	The stack trace of the failure.

RecipeRunStats

Recipe performance

org.openrewrite.table.RecipeRunStats

Statistics used in analyzing the performance of recipes.

Column Name	Description
The recipe	The recipe whose stats are being measured both individually and cumulatively.
Source file count	The number of source files the recipe ran over.
Source file changed count	The number of source files which were changed in the recipe run. Includes files created, deleted, and edited.
Cumulative scanning time (ns)	The total time spent across the scanning phase of this recipe.
Max scanning time (ns)	The max time scanning any one source file.
Cumulative edit time (ns)	The total time spent across the editing phase of this recipe.
Max edit time (ns)	The max time editing any one source file.