Warning dead code in try-with-resources but not in try-catch-finally translation

Question

The following code uses try-with-resources , created in Java 8. occasionallyThrow () is declared to throw an OccasionalException , the Resource method close () to throw a CloseException . Eclipse (Version: Neon Release (4.6.0), Build id: 20160613-1800) adds a warning to the line marked with // dead code that the branch is dead code. Implicitly, Eclipse claims that the line marked with // live code is not dead code.

Object tryWithResources() throws OccasionalException {
    Object value = null;
    try (Resource resource = new Resource()) {
        occasionallyThrow();
        value = new Object();
    }
    catch (CloseException e) {
        if (value == null) {
            // alive code
        }
        else {
            // dead code
        }
    }
    return value;
}

. Throw() OccasionalException, try -with-resources . CloseException, OccasionalException, CloseException. , , CloseException, catch try , , null. , " " , " " . , , , , , , " " .

, , , try-with-resources, . ( , , 14.20.3.2. try-with-resources, , t , & hellip;)

Object expandedTry() throws OccasionalException {
    Object value = null;
    try {
        Resource resource = new Resource();
        Throwable $primary = null;
        try {
            occasionallyThrow();
            value = new Object();
        }
        catch (Throwable t) {
            $primary = t;
            throw t;
        }
        finally {
            if (resource != null) {
                if ($primary != null) {
                    try {
                        resource.close();
                    }
                    catch (Throwable $suppressed) {
                        $primary.addSuppressed($suppressed);
                    }
                }
                else {
                    resource.close();
                }
            }
        }
    }
    catch (CloseException e) {
        if (value == null) {
            // alive (not dead!)
        }
        else {
            // alive
        }
    }
    return value;
}

-, if-else , ?

, .

public class TestTryWithResources {

    /** Exception thrown by Resource close() method */
    @SuppressWarnings("serial")
    static class CloseException extends Exception {}

    /** AutoCloseable declared to throw a CloseException */ 
    static class Resource implements AutoCloseable {
        @Override
        public void close() throws CloseException {}
    }

    /** An occasionally thrown exception */
    @SuppressWarnings("serial")
    static class OccasionalException extends Exception {}

    /** Method declared to throw an occasional exception */
    void occasionallyThrow() throws OccasionalException {}

    /*
     * Method using try-with-resources.  Eclipse warns that the 
     * portion marked with "// dead code" is Dead code.
     */
    Object tryWithResources() throws OccasionalException {
        Object value = null;
        try (Resource resource = new Resource()) {
            occasionallyThrow();
            value = new Object();
        }
        catch (CloseException e) {
            if (value == null) {
                // alive code
            }
            else {
                // dead code
            }
        }
        return value;
    }

    /*
     * Method not using try-with-resources.  This is the translation
     * of the try-with-resources in tryWithResources, according to 
     * [14.20.3 try-with-resources][1].  Eclipse does not warn about 
     * any of the code being Dead code.
     * 
     * [1]: https://docs.oracle.com/javase/specs/jls/se7/html/jls-14.html#jls-14.20.3 
     */
    Object expandedTry() throws OccasionalException {
        Object value = null;
        try {
            Resource resource = new Resource();
            Throwable $primary = null;
            try {
                occasionallyThrow();
                value = new Object();
            }
            catch (Throwable t) {
                $primary = t;
                throw t;
            }
            finally {
                if (resource != null) {
                    if ($primary != null) {
                        try {
                            resource.close();
                        }
                        catch (Throwable $suppressed) {
                            $primary.addSuppressed($suppressed);
                        }
                    }
                    else {
                        resource.close();
                    }
                }
            }
        }
        catch (CloseException e) {
            if (value == null) {
                // alive
            }
            else {
                // alive
            }
        }
        return value;
    }
}

Amin J Eclipse. . , , , Luna, Neon:

Answer 1

- , try, .

try-with-resources , .

, , , ( ), (, Eclipse Luna).

Object tryWithResources() throws OccasionalException {
    Object value = null;
    try (Resource resource = new Resource()) {
        occasionallyThrow();
        value = new Object();
        resource.someMethod(); // using the resource, so eclipse thinks it not closed yet (correctly)
    }
    catch (CloseException e) {
        if (value == null) {
            // alive code
        }
        else {
            // dead code
        }
    }
    return value;
}

UPDATE

, ( ) .

        Object val = null;

        try (BufferedReader reader = new BufferedReader(new FileReader("C:\\file.txt"))) {
            val = new Object();
            System.out.println("got here");
            reader.readLine();
        }
        catch(IOException e){
            System.out.println("io ex");
            if ( val == null){

            }
            else{

            }
        }

Answer 2

, Eclipse , , , , . catch, , , , , , :

Object tryWithResources() throws OccasionalException {
    Object value = null;
    try (Resource resource = new Resource()) {
        occasionallyThrow();
        value = new Object();
        System.out.println(resource.toString());
    }
    catch (CloseException e) {
        catchBlock(value, e);  // call auxiliary method
    }
    return value;
}

void catchBlock(Object value, CloseException e) {
    if (value == null) {
        // then
    }
    else {
        // else
    }
}