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Remove catch for a checked exception if the try block does not throw that exception

org.openrewrite.staticanalysis.UnnecessaryCatch

A refactoring operation may result in a checked exception that is no longer thrown from a try block. This recipe will find and remove unnecessary catch blocks.

Recipe source​

GitHub, Issue Tracker, Maven Central

This recipe is available under the Moderne Source Available License.

Options​

TypeNameDescriptionExample
booleanincludeJavaLangExceptionOptional. Whether to include java.lang.Exception in the list of checked exceptions to remove. Unlike other checked exceptions, java.lang.Exception is also the superclass of unchecked exceptions. So removing catch(Exception e) may result in changed runtime behavior in the presence of unchecked exceptions. Default false
booleanincludeJavaLangThrowableOptional. Whether to include java.lang.Throwable in the list of exceptions to remove. Unlike other checked exceptions, java.lang.Throwable is also the superclass of unchecked exceptions. So removing catch(Throwable e) may result in changed runtime behavior in the presence of unchecked exceptions. Default false

Example​

Parameters​
ParameterValue
includeJavaLangExceptionfalse
includeJavaLangThrowablefalse
Before​
import java.io.IOException;

public class AnExample {
    public void method() {
        try {
            java.util.Base64.getDecoder().decode("abc".getBytes());
        } catch (IOException e) {
            System.out.println("an exception!");
        }
    }
}
After​
public class AnExample {
    public void method() {
        java.util.Base64.getDecoder().decode("abc".getBytes());
    }
}

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.UnnecessaryCatch")
    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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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​

Tyler Van Gorder, Auke Schrijnen, Sam Snyder, Jonathan Schnéider, Knut Wannheden, Tim te Beek