Re: unnecessary code in Oracle example?

From:
Jim Janney <jjanney@shell.xmission.com>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 09 Oct 2013 14:21:07 -0600
Message-ID:
<ydna9iijivg.fsf@shell.xmission.com>
markspace <markspace@nospam.nospam> writes:

On 10/9/2013 12:08 PM, Jim Janney wrote:

Thanks. But that looks like a good idiom to avoid. I prefer

    MyResource r1 = openResource();
    try {
       MyResource r2 = openResource2();
       try {
         // do something
       } finally {
         r2.close();
       }
    } finally {
      r1.close();
    }

Not as pretty syntactically, perhaps, but much clearer semantically.


I don't like either one. Why not take advantage of the fact that
resources are specified to be closed in the opposite order that they
are declared in a try-with-resources?

The following demonstrates this by closing the named streams in the
order C-B-A:

package quicktest;

import java.io.IOException;
import java.io.InputStream;

public class TryResourcesTest
{
   public static void main( String[] args ) throws Exception
   {
      try(
          MyTestStream a = new MyTestStream( "A" );
          MyTestStream b = new MyTestStream( "B" );
          MyTestStream c = new MyTestStream( "C" )
      ) {
         System.out.println( a.read()+b.read()+c.read() );
      }
   }
}

class MyTestStream extends InputStream {

   private final String name;

   public MyTestStream( String name ) {
      this.name = name;
   }

   @Override
   public int read() throws IOException {
      return 42;
   }

   @Override
   public void close() {
      System.out.println( getClass().getSimpleName()+
       ":"+name+" closed." );
   }
}


Yes, in Java 7 you can have clean syntax and clean semantics. Looks
like a win all around.

--
Jim Janney

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