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From: markspace <markspace@nospam.nospam>
Newsgroups: comp.lang.java.programmer
Subject: Re: unnecessary code in Oracle example?
Date: Wed, 09 Oct 2013 12:27:29 -0700
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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." );
    }
}