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Replace referential equality operators with Object equals method invocations when the operands both override Object.equals(Object obj)

org.openrewrite.staticanalysis.ReferentialEqualityToObjectEquals

Using == or != compares object references, not the equality of two objects. This modifies code where both sides of a binary operation (== or !=) override Object.equals(Object obj) except when the comparison is within an overridden Object.equals(Object obj) method declaration itself. The resulting transformation must be carefully reviewed since any modifications change the program's semantics.

Tags​

Recipe source​

GitHub, Issue Tracker, Maven Central

This recipe is available under the Moderne Source Available License.

Example​

Before​
class T {
    void doSomething() {
        A a1 = new A();
        A a2 = new A();
        if (a1 == a2) {}
    }
    class A {
        @Override
        public boolean equals(Object anObject) {return true;}
    }
}
After​
class T {
    void doSomething() {
        A a1 = new A();
        A a2 = new A();
        if (a1.equals(a2)) {}
    }
    class A {
        @Override
        public boolean equals(Object anObject) {return true;}
    }
}

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):

  1. Add the following to your build.gradle file:
build.gradle
plugins {
    id("org.openrewrite.rewrite") version("7.6.1")
}

rewrite {
    activeRecipe("org.openrewrite.staticanalysis.ReferentialEqualityToObjectEquals")
    setExportDatatables(true)
}

repositories {
    mavenCentral()
}

dependencies {
    rewrite("org.openrewrite.recipe:rewrite-static-analysis:2.9.0")
}
  1. Run gradle rewriteRun to run the recipe.

See how this recipe works across multiple open-source repositories​

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Please contact Moderne for more information about safely running the recipes on your own codebase in a private SaaS.

Data Tables​

Source files that had results​

org.openrewrite.table.SourcesFileResults

Source files that were modified by the recipe run.

Column NameDescription
Source path before the runThe source path of the file before the run. null when a source file was created during the run.
Source path after the runA 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 changesIn 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 changesThe specific recipe that made a change.
Estimated time savingAn estimated effort that a developer to fix manually instead of using this recipe, in unit of seconds.
CycleThe recipe cycle in which the change was made.

Contributors​

Patrick Way, Tim te Beek, traceyyoshima, Jonathan Schnéider, Knut Wannheden, Sam Snyder