Stephen Connolly stephenc

For use when you have multiple JVM providers (Apple & Oracle), you want to be able to switch between JDKs for each CLI

usejava ()
{
    local sel=$1.jdk
    if [ -x "/Library/Java/JavaVirtualMachines/jdk$sel/Contents/Home/bin/java" -a ! -x "/Library/Java/JavaVirtualMachines/$1/Contents/Home/bin/java" ]
    then
        sel=jdk$sel
    fi
    local base=/Library/Java/JavaVirtualMachines
    if [ -x "/System/Library/Java/JavaVirtualMachines/$sel/Contents/Home/bin/java" ]
    then
        base=/System/Library/Java/JavaVirtualMachines
    fi
    if [ -z "$1" -o ! -x "$base/$sel/Contents/Home/bin/java" ]
    then
        local prefix="Syntax: usejava "
        for i in /Library/Java/JavaVirtualMachines/* /System/Library/Java/JavaVirtualMachines/*
        do
            if [ -x "$i/Contents/Home/bin/java" ]
            then
                /bin/echo -n "$prefix$(basename $i | sed -e "s/^jdk//;s/\.jdk$//;")"
                prefix=" | "
            fi
        done
        /bin/echo ""
    else
        if [ -z "$JAVA_HOME" ]
        then
            export PATH=$base/$sel/Contents/Home/bin:$PATH
        else
            export PATH=$(echo $PATH|sed -e "s:$JAVA_HOME/bin:$base/$sel/Contents/Home/bin:g")
        fi
        export JAVA_HOME=$base/$sel/Contents/Home
        echo -n -e "\033]0;$(java -version 2>&1 | sed -e "s/.*\"\(.*\)\".*/Java \1/;q")\007"
    fi
}

There is additional fun to be had, given that most Java based launchers that try to fix JAVA_HOME when not set will guess the Apple JVM path… so the following Java program can help

http://j.mp/TfdoxL a link to a free online iOS app development training course that looks worth checking out

Special Symbols and Characters on the regular Mac Keyboard

These are for the British Keyboard layout

Currency Symbols

$

dollar

Shift+4

¢

cents

Option+4

£

pound

Shift+3

¥

yen

Option+y

€

Euro

Option+2

Trademark and Copyright Symbols

©

copyright

Option+g

®

registered

Option+r

™

trademark

Option+Shift+2

Apple Symbol



apple

Option+Shift+K

Math and Greek Character Symbols

±

plus-or-minus

Option+Shift+Equals

µ

micro

Option+h

π

pi

Option+l (as in L is for llama)

√

square root

Option+t

÷

divided by

Option+/ (slash is key to the left of right-hand shift key)

This is a repost of my post on the CloudBees Developers blog

TL;DR Source control injection attacks are a bigger worry than build tool injection attacks, and if you cannot trust your local filesystem, then you cannot trust anything.

A few exchanges on twitter have prompted me to write a fuller blog post on the subject of Cross-Build Injection (XBI) Attacks.

The idea of XBI is that you trick the developer and replace parts of their code with your code, thereby getting your code to be trusted by the developer.

Hamlet: … for there is nothing either good or bad, but thinking makes it so.

Hamlet Act 2, scene 2, 239–251

William Shakespeare

The Apache Software Foundation is a meritocracy. By this we mean that you gain status based on the merit of your work and actions. In fact the status that you gain is a recognition of the merit of your work and actions.

Maven is an Apache project, that means that we have to follow the Apache rules and way. One of those rules is that we cannot hand out commit access to anyone who asks for it.

Cmd+Shift+4 followed by Space is a lovely way to get a screen shot of a window on an Apple Mac…

In fact here is one such screenshot:

Notice the nice shadow effect around the screenshot? Ever wanted to add that shadow effect to your non-mac screenshots?

ImageMagick is your friend

convert NoShadowScreenshot.png ( +clone -background black -shadow 80x20+0+15 ) +swap -background transparent -layers merge +repage WithShadowScreenshot.png

There you are, nice equivalent shadow added.

With Java Generics, it can be useful to insert wildcards wherever possible, but how do you decide which wildcard is correct? When do you use ? super T, ? extends T and when should you not use a wildcard at all.

The Get and Put principle: Use an extends wildcard when you only get values from the structure. Use a super wildcard when you only put values into the structure. Don’t use a wildcard when you both get and put values from/into the structure.

Book review: “EJB 3.1 Cookbook” by Richard M. Reese

Review

The kind people at Packt gave me a copy of “EJB 3.1 Cookbook” by Richard M. Reese to review. This book should be viewed as a collection of building block recipes, not as a collection of meal plans, and not as a how to cook book that you would read from cover to cover. When I look at the book from this point of view, I think that it is well structured and put together and the content is pitched just about right. This book does not tell you when to use a specific recipe, so it would be a mistake to think that this is the only book you would need for EJB 3.1. However, when you need a “Béchamel sauce”, this is a book that you can go to, quickly find and open up the right section and read the recipe to refresh your mind and get cooking.

Java has a couple of “nice” features, specifically:

Built-in locks

Baked in support for object serialization

Now I don’t want to get into a war about how both of these are flawed (there was a reason that I put “nice” in quotes) but here is a quick note on how to make the two play nice (more as a reference to myself… but if others find this useful, well and good).

There has been this idea running around the back of my head for a while, and it’s only now that it is starting to crystalize into something that I can express.

When we look at Open Source projects, we see that there is a hierarchy of involvement. There are different levels at which you can be involved, and at each higher level, there will be less and less individuals. For now I am going to divide involvement up like this: