stringliteralequality.md

Use String.equals() on String literals

org.openrewrite.staticanalysis.StringLiteralEquality

String.equals() should be used when checking value equality on String literals. Using == or != compares object references, not the actual value of the Strings. This only modifies code where at least one side of the binary operation (== or !=) is a String literal, such as "someString" == someVariable;. This is to prevent inadvertently changing code where referential equality is the user's intent.

Tags

• RSPEC-4973

Source

GitHub, Issue Tracker, Maven Central

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

Example

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

Before

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

import java.util.List;
class Test {
    public String getString() {
        return "stringy";
    }

    public void method(String str) {
        if (str == "test") ;
        if ("test" == str) ;
        if ("test" == "test") ;
        if ("test" == new String("test")) ;
        if ("test" == getString());
        boolean flag = (str == "test");
        while ("test" == str) {
        }
    }

    public void findPeter(List<Friend> friends) {
        friends.stream().filter(e -> e.name == "peter");
    }

    class Friend {
        String name;
    }
}

{% endcode %}

After

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

import java.util.List;
class Test {
    public String getString() {
        return "stringy";
    }

    public void method(String str) {
        if ("test".equals(str)) ;
        if ("test".equals(str)) ;
        if ("test".equals("test")) ;
        if ("test".equals(new String("test"))) ;
        if ("test".equals(getString()));
        boolean flag = ("test".equals(str));
        while ("test".equals(str)) {
        }
    }

    public void findPeter(List<Friend> friends) {
        friends.stream().filter(e -> "peter".equals(e.name));
    }

    class Friend {
        String name;
    }
}

{% endcode %}

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

--- Test.java
+++ Test.java
@@ -8,7 +8,7 @@

    public void method(String str) {
-       if (str == "test") ;
-       if ("test" == str) ;
-       if ("test" == "test") ;
-       if ("test" == new String("test")) ;
-       if ("test" == getString());
-       boolean flag = (str == "test");
-       while ("test" == str) {
+       if ("test".equals(str)) ;
+       if ("test".equals(str)) ;
+       if ("test".equals("test")) ;
+       if ("test".equals(new String("test"))) ;
+       if ("test".equals(getString()));
+       boolean flag = ("test".equals(str));
+       while ("test".equals(str)) {
        }
@@ -19,1 +19,1 @@

    public void findPeter(List<Friend> friends) {
-       friends.stream().filter(e -> e.name == "peter");
+       friends.stream().filter(e -> "peter".equals(e.name));
    }

{% 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.StringLiteralEquality")
}

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.StringLiteralEquality</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.StringLiteralEquality

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

Contributors

• Knut Wannheden
• Aaron Gershman
• Jonathan Schneider
• Sam Snyder
• Patrick

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