Try-with-resources: Must I throw or catch the close() method's exceptions? [duplicate]

Answer 1

Quote from Java Language Specification ($14.20.3.2):

14.20.3.2 Extended try-with-resources

A try-with-resources statement with at least one catch clause and/or a finally clause is called an extended try-with-resources statement. The meaning of an extended try-with-resources statement:

    try ResourceSpecification
        Block
    Catches_opt
    Finally_opt

is given by the following translation to a basic try-with-resources statement (§14.20.3.1) nested inside a try-catch or try-finally or try-catch-finally statement:

    try {
        try ResourceSpecification
            Block
    }
    Catches_opt
    Finally_opt

The effect of the translation is to put the ResourceSpecification "inside" the try statement. This allows a catch clause of an extended try-with-resources statement to catch an exception due to the automatic initialization or closing of any resource.

So, basically, wrapper is already implemented

Answer 2

From the Java tutorial

A try-with-resources statement can have catch and finally blocks just like an ordinary try statement. In a try-with-resources statement, any catch or finally block is run after the resources declared have been closed.

(emphasis mine)

So you can simply do

try (BufferedReader br =
               new BufferedReader(new FileReader(path))) {
    return br.readLine();
}
catch (IOException e) {
    // handle the exception that has been thrown by readLine() OR by close().
}

Answer 3

You do not need to wrap the try-with-resources in another try-catch block, you simply add a catch block:

class Foo implements AutoCloseable {
    public void close() throws Exception {
        throw new Exception();
    }
}

public class Try {
    public static void main(final String[] args) {
        try(Foo f = new Foo()) {
            System.out.println("No op!");
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}

Answer 4

You should be able to simply add the appropriate catch (Exception e) { } clause. If you need to do special handling for a specific one, or you can simply catch Exception, if you need it much broader.

try (Statement stmt = con.createStatement()) {
    ResultSet rs = stmt.executeQuery(query);

    while (rs.next()) {
        String coffeeName = rs.getString("COF_NAME");
        int supplierID = rs.getInt("SUP_ID");
        float price = rs.getFloat("PRICE");

        System.out.println(coffeeName + ", " + supplierID + ", " + 
                           price + ", " + sales + ", " + total);
    }
} catch (Exception e) {
    System.out.println("Exception while trying to through the queries. ", e);
}

Since it's Java 7, you can actually put multiple exceptions per catch clause, or you can simply catch the outermost exception you want.