Over a million developers have joined DZone.

Problems debugging Java after ANT compile

DZone's Guide to

Problems debugging Java after ANT compile

· Java Zone
Free Resource

Learn how our document data model can map directly to how you program your app, and native database features like secondary indexes, geospatial and text search give you full access to your data. Brought to you in partnership with MongoDB.

Ok, this one is pretty easy but worth posting. I lost a few hours because of it and I don't want the same to happen to you! Suppose you want to be able to pass a switch into an ANT target which performs a javac to tell it to include debug information or not.

Your properties file will contain properties such as:


The ANT compile target then uses these properties:
<project default="help" name="my-proj">
 <property file="build.properties"></property>
 <target name="compile">
  <echo message="compiling code"></echo>
  <echo message="compile.debug=${compile.debug}"></echo>
  <echo message="compile.debug.level=${compile.debug.level}"></echo>
  <javac srcdir="${SRC.DIR}"

However, the debug information is not there when you are debugging.  You run
ant -v compile to get more information. You see:
     [echo] This target compiles everything.
     [echo] Compiling java classes...
     [echo] compile.debug=true
     [echo] compile.debug.level=lines,vars,source
    [javac] ...
    [javac] Compiling ...
    [javac] Using modern compiler
    [javac] Compilation arguments:
    [javac] '-deprecation'
    [javac] '-d'
    [javac] ...
    [javac] '-classpath'
    [javac] ...
    [javac] '-g:none'
    [javac] '-O'
    [javac] ...

Now, as we can see the properties are echo'd as expected.  But, the "-g:none" indicates the compile won't include debug information.  Before you tear your hair out, relax! You have just made a very silly mistake we all make at sometime. When ANT reads property files it reads all property values literally. This means there is a difference between "true" and "true ", i.e. boolean properties should not have trailing spaces otherwise they will not be read as boolean properties. This is what happened here.  Ouch!
Ouch - trailing space!

As it states in  http://ant.apache.org/manual/Tasks/property.html, regarding property files: "Trailing spaces are not stripped. It may have been what you wanted."

So rip that trailing space and re-run the ant compile target.

You should see:
[javac] '-g:lines,vars,source'

which means the compiler is going to add lines, vars and source debug information.  Happy debugging!

1. http://ant.apache.org/manual/Tasks/property.html


From http://dublintech.blogspot.com/2011/10/problems-debugging-java-after-ant.html

Discover when your data grows or your application performance demands increase, MongoDB Atlas allows you to scale out your deployment with an automated sharding process that ensures zero application downtime. Brought to you in partnership with MongoDB.


Opinions expressed by DZone contributors are their own.


Dev Resources & Solutions Straight to Your Inbox

Thanks for subscribing!

Awesome! Check your inbox to verify your email so you can start receiving the latest in tech news and resources.


{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}