useforeachremoveinsteadofsetremoveall.md

Replace java.util.Set#removeAll(java.util.Collection) with java.util.Collection#forEach(Set::remove)

org.openrewrite.staticanalysis.UseForEachRemoveInsteadOfSetRemoveAll

Using java.util.Collection#forEach(Set::remove) rather than java.util.Set#removeAll(java.util.Collection) may improve performance due to a possible O(n^2) complexity.

Source

GitHub, Issue Tracker, Maven Central

• groupId: org.openrewrite.recipe
• artifactId: rewrite-static-analysis
• version: 1.0.1

Example

{% tabs %} {% tab title="T.java" %}

Before

{% code title="T.java" %}

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

class T {
    static {
        Set<String> s = new HashSet<>();
        List<String> l = Collections.singletonList("a");
        s.removeAll(l);
    }

    Set<String> removeFromSet(Set<String> s, Collection<String> c) {
        s.removeAll(c);
        return s;
    }
}

{% endcode %}

After

{% code title="T.java" %}

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

class T {
    static {
        Set<String> s = new HashSet<>();
        List<String> l = Collections.singletonList("a");
        l.forEach(s::remove);
    }

    Set<String> removeFromSet(Set<String> s, Collection<String> c) {
        c.forEach(s::remove);
        return s;
    }
}

{% endcode %}

{% endtab %} {% tab title="Diff" %} {% code %}

--- T.java
+++ T.java
@@ -11,1 +11,1 @@
        Set<String> s = new HashSet<>();
        List<String> l = Collections.singletonList("a");
-       s.removeAll(l);
+       l.forEach(s::remove);
    }
@@ -15,1 +15,1 @@

    Set<String> removeFromSet(Set<String> s, Collection<String> c) {
-       s.removeAll(c);
+       c.forEach(s::remove);
        return s;

{% endcode %} {% endtab %} {% endtabs %}

Usage

This recipe has no required configuration options. It can be activated by adding a dependency on org.openrewrite.recipe:rewrite-static-analysis:1.0.1 in your build file or by running a shell command (in which case no build changes are needed): {% tabs %} {% tab title="Gradle" %} {% code title="build.gradle" %}

plugins {
    id("org.openrewrite.rewrite") version("6.1.4")
}

rewrite {
    activeRecipe("org.openrewrite.staticanalysis.UseForEachRemoveInsteadOfSetRemoveAll")
}

repositories {
    mavenCentral()
}

dependencies {
    rewrite("org.openrewrite.recipe:rewrite-static-analysis:1.0.1")
}

{% endcode %} {% endtab %} {% tab title="Maven POM" %} {% code title="pom.xml" %}

<project>
  <build>
    <plugins>
      <plugin>
        <groupId>org.openrewrite.maven</groupId>
        <artifactId>rewrite-maven-plugin</artifactId>
        <version>5.2.4</version>
        <configuration>
          <activeRecipes>
            <recipe>org.openrewrite.staticanalysis.UseForEachRemoveInsteadOfSetRemoveAll</recipe>
          </activeRecipes>
        </configuration>
        <dependencies>
          <dependency>
            <groupId>org.openrewrite.recipe</groupId>
            <artifactId>rewrite-static-analysis</artifactId>
            <version>1.0.1</version>
          </dependency>
        </dependencies>
      </plugin>
    </plugins>
  </build>
</project>

{% endcode %} {% endtab %}

{% tab title="Maven Command Line" %} {% code title="shell" %} You will need to have Maven installed on your machine before you can run the following command.

mvn -U org.openrewrite.maven:rewrite-maven-plugin:run \
  -Drewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-static-analysis:RELEASE \
  -Drewrite.activeRecipes=org.openrewrite.staticanalysis.UseForEachRemoveInsteadOfSetRemoveAll

{% endcode %} {% endtab %} {% endtabs %}

Contributors

• Patrick Way
• Knut Wannheden
• Patrick

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