C#

CSHARP.STRUCT.EXCP.EEH : Empty Exception Handler (C#)

要旨

An exception handler has an empty body.

This checker controls if exception handlers might be incorrect. For instance, an exception handler with an empty body might be an unfinished snippet of code; an exception handler for a very generic exception type might end up catching too many exceptions, also some that were not meant to be caught there.

プロパティ

クラス名 Empty Exception Handler (C#)
日本語クラス名 Empty Exception Handler (C#)
クラス分類 信頼性 (reliability)
ニーモニック CSHARP.STRUCT.EXCP.EEH
カテゴリー
CWE CWE:390 Detection of Error Condition Without Action
対応言語 C# で利用可能です。
有効/無効設定 このワーニングクラスのチェックはデフォルトで有効になっています。チェックを無効にするにはプロジェクト設定ファイル （configuration file）に以下の WARNING_FILTER ルールを追加してください。 
WARNING_FILTER += discard class="Empty Exception Handler (C#)"

例 

using System;
using System.IO;


namespace DocumentationExamples
{

    public class ExceptionHandlers
    {
        public static void Main(string[] args)
        {
            StreamWriter fw = null;
            try
            {
                fw = new StreamWriter(args[0]);
                fw.Dispose();
            }
            catch (IndexOutOfRangeException e) { }  // Empty Exception Handler (C#) warning issued here
            catch (Exception e)                     // Generic Exception Handler (C#) warning issued here
            {
                Console.WriteLine("unusual");
            }
        }
    }
}

The programmer could resolve these warnings as follows. 

public static void Main(string[] args)
{
    StreamWriter fw = null;
    try
    {
        fw = new StreamWriter(args[0]);
        fw.Dispose();
    }
    catch (IndexOutOfRangeException e) {         // resolve "Empty Exception Handler (C#)" warning by printing a message to the user
        Console.WriteLine("usage: Main filename");
    } 
    catch (IOException e)                        // resolve "Generic Exception Handler (C#)" warning by catching IOException instead of Exception
    {
        Console.WriteLine("I/O error");
    }
}

解決法

Add a body to the exception handler, or narrow to the exception types.

注釈

Sometimes, an empty handler is needed since the compiler does not know that an exception will never be thrown there. If the analyzer recognizes that situation, it will not issue any warning for the empty exception handler. For instance, in the following program:

public class CloneOK implements Cloneable {
  private int f;

  public CloneOK(int f) {
    this.f = f;
  }

  @Override
  protected Object clone() {
    CloneOK result = null;

    try {
      System.out.println("Starting cloning");
      result = (CloneOK) super.clone();
      result.f = f;
      System.out.println("Finished cloning");
    }
    catch (CloneNotSupportedException e) {
    }

    return result;
  }

  public static void main(String[] args) {
    new CloneOK(13).clone();
  }
}

This checker will not issue any warning, since the call to super.clone() is applied to a cloneable object this and will consequently never throw a CloneNotSupportedException. The programmer must nevertheless write that empty handler, since otherwise the compiler will not compile the program.

関連のある設定ファイルパラメータ

設定ファイルの以下のパラメータがこのワーニングクラスのチェックに影響します。