Open source

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

Recipe IDorg.openrewrite.staticanalysis.UnnecessaryCatch

Artifactorg.openrewrite.recipe:rewrite-static-analysis

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.

Single recipeOpenRewriteModerne Source Available License

Try in PlatformTry this recipe in the Moderne platform. Not a user yet? You’ll get a no-setup demo environment, with nothing to install or configure.

Options

2 parameters

2 optional

Parameter	Example	Type	Required
includeJavaLangException	—	boolean	Optional
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
includeJavaLangThrowable	—	boolean	Optional
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

Examples

java

Parameter	Value
includeJavaLangException	false
includeJavaLangThrowable	false

java

Before

import java.io.IOException;

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

After

class AnExample {
    void method() {
        java.util.Base64.getDecoder().decode("abc".getBytes());
    }
}

Diff

@@ -1,2 +1,0 @@
-import java.io.IOException;
-
class AnExample {
@@ -5,5 +3,1 @@
class AnExample {
    void method() {
-       try {
-           java.util.Base64.getDecoder().decode("abc".getBytes());
-       } catch (IOException e) {
-           System.out.println("an exception!");
-       }
+       java.util.Base64.getDecoder().decode("abc".getBytes());
    }

Usage

Run this recipe

This recipe has no required configuration options. Users of Moderne can run it via the 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 UnnecessaryCatch

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

mod config recipes jar install org.openrewrite.recipe:rewrite-static-analysis:2.37.0

Data tables

Source files that had results

org.openrewrite.table.SourcesFileResults

Source files that were modified by the recipe run.

Column	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.

Source files that had search results

org.openrewrite.table.SearchResults

Search results that were found during the recipe run.

Column	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.

Source files that errored on a recipe

org.openrewrite.table.SourcesFileErrors

The details of all errors produced by a recipe run.

Column	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.

Recipe performance

org.openrewrite.table.RecipeRunStats

Statistics used in analyzing the performance of recipes.

Column	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.