Is -1 a magic number? An anti-pattern? A code smell? Quotes and guidelines from authorities

Posted by polygenelubricants on Stack Overflow See other posts from Stack Overflow or by polygenelubricants
Published on 2010-06-13T11:03:50Z Indexed on 2010/06/13 11:12 UTC
Read the original article Hit count: 294

Filed under:

java

|

best-practices

|

magic-numbers

I've seen -1 used in various APIs, most commonly when searching into a "collection" with zero-based indices, usually to indicate the "not found" index. This "works" because -1 is never a legal index to begin with. It seems that any negative number should work, but I think -1 is almost always used, as some sort of (unwritten?) convention.

I would like to limit the scope to Java at least for now. My questions are:

What are the official words from Sun regarding using -1 as a "special" return value like this?
What quotes are there regarding this issue, from e.g. James Gosling, Josh Bloch, or even other authoritative figures outside of Java?
What were some of the notable discussions regarding this issue in the past?

© Stack Overflow or respective owner

Related posts about java

Tomcat 6: Access Control Exception?

as seen on Server Fault - Search for 'Server Fault'
I'm trying to setup a tomcat6 server, and I'm trying to match another setup someone else established. However, my deployment (default Ubuntu install) uses a policy.d/ directory structure, and the established server just uses a catalina.policy file. I've tried setting every entry in policy.d to match… >>> More
Problem in creation MDB Queue connection at Jboss StartUp

as seen on Stack Overflow - Search for 'Stack Overflow'
I am not able to create a Queue connection in JBOSS4.2.3GA Version & Java1.5, as I am using MDB as per the below details. I am putting this MDB in a jar file(named utsJar.jar) and copied it in deploy folder of JBOSS, In the test env. this MDB works well but in another env. [ env settings and… >>> More
failing to establish connection between Postgres db and gwt

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am using Postgres and gwt 2.0 for one of my applications. I am facing problem connecting to the database. When I try to connect it gives "ClassNotFoundException". Here is what I get when I try to connect to database: java.lang.ClassNotFoundException: org.postgresql.Driver at java.net… >>> More
failing to establish connection between postgre db and gwt

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, For i am using postgre and gwt 2.0 for one of my applications. I am facing problem connecting to the database. When i try to connect it gives "ClassNotFoundException". Here is what i get when i try to connect to database: java.lang.ClassNotFoundException: org.postgresql.Driver at java.net… >>> More
Migration and deployement problems JBoss 4.2.2.GA to JBoss 6.0.0.M2

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I'm trying to migrate an application running on JBoss 4.2.2.GA to JBoss 6.0.0.M2 I give you some log to explain my problem : boot.log : 2010-03-16 09:59:29,406 ERROR [org.jboss.system.server.profileservice.ProfileServiceBootstrap] (Thread-2) Failed to load profile: Summary of incomplete deployments… >>> More

Related posts about best-practices

Batch Best Practices and Technical Best Practices Updated

as seen on Oracle Blogs - Search for 'Oracle Blogs'
The Batch Best Practices for Oracle Utilities Application Framework based products (Doc Id: 836362.1) and Technical Best Practices for Oracle Utilities Application Framework Based Products (Doc Id: 560367.1) have been updated with updated and new advice for the various versions of the Oracle… >>> More
Partial template specialization of free functions - best practices

as seen on Stack Overflow - Search for 'Stack Overflow'
As most C++ programmers should know, partial template specialization of free functions is disallowed. For example, the following is illegal C++: template <class T, int N> T mul(const T& x) { return x * N; } template <class T> T mul<T, 0>(const T& x) { return T(0); } //… >>> More
Object Oriented PHP Best Practices

as seen on Stack Overflow - Search for 'Stack Overflow'
Say I have a class which represents a person, a variable within that class would be $name. Previously, In my scripts I would create an instance of the object then set the name by just using: $object->name = "x"; However, I was told this was not best practice? That I should have a function set_name()… >>> More
Good place to look for example Database Designs - Best practices

as seen on Stack Overflow - Search for 'Stack Overflow'
I have been given the task to design a database to store a lot of information for our company. Because the task is rather big and contains multiple modules where users should be able to do stuff, I'm worried about designing a good data model for this. I just don't want to end up with a badly designed… >>> More
Notification Email Best Practices--From Server Setup to Programming

as seen on Stack Overflow - Search for 'Stack Overflow'
All, I'm in the process now of building a SaaS tool that allows network admins to generate notification emails to the members of the end-users of our platform (among many many other things). I'm running into a bit of an "out of my expertise" wall, as I know there are a lot of variables involved… >>> More