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From: Steven Simpson <ss@domain.invalid>
Newsgroups: comp.lang.java.help
Subject: Re: IDE suggestion
Date: Sun, 24 Feb 2013 21:31:14 +0000
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On 24/02/13 20:23, Lew wrote:
> Lightest weight is a text editor plus Ant plus command line, which works
> just fine.

I came to the conclusion that Ant is insufficient without an 
error-detecting editor (as in an IDE).  If class Foo uses class Bar, 
class Bar could be changed in a way that causes an error in Foo, yet Ant 
will not detect that Foo needs to be recompiled in order to see the 
error, which goes unnoticed until runtime, or until Foo is re-compiled.

Is my conclusion incorrect?  Am I using Ant correctly?:

% cat build.xml
<project default="compile">
   <target name="compile">
     <mkdir dir="classes" />
     <javac srcdir="src" destdir="classes"
            listfiles="yes" includeDestClasses="true"
            includeAntRuntime="false" />
   </target>

   <target name="clean">
     <delete dir="classes" />
   </target>
</project>
% cat src/Foo.java
public class Foo {
     public static void main(String[] args) throws Exception {
         new Bar();
     }
}

% cat src/Bar.java
public class Bar { }

% ant clean
Buildfile: /scratch/simpsons/Scratch/Coding/antfail2/build.xml

clean:
    [delete] Deleting directory /scratch/simpsons/Scratch/Coding/antfail2/classes

BUILD SUCCESSFUL
Total time: 0 seconds
% ant
Buildfile: /scratch/simpsons/Scratch/Coding/antfail2/build.xml

compile:
     [mkdir] Created dir: /scratch/simpsons/Scratch/Coding/antfail2/classes
     [javac] Compiling 2 source files to /scratch/simpsons/Scratch/Coding/antfail2/classes
     [javac] /scratch/simpsons/Scratch/Coding/antfail2/src/Bar.java
     [javac] /scratch/simpsons/Scratch/Coding/antfail2/src/Foo.java

BUILD SUCCESSFUL
Total time: 0 seconds
% java -cp classes Foo
% sed -e 's/class/abstract class/' -i src/Bar.java
% cat src/Bar.java
public abstract class Bar { }

% ant
Buildfile: /scratch/simpsons/Scratch/Coding/antfail2/build.xml

compile:
     [javac] Compiling 1 source file to /scratch/simpsons/Scratch/Coding/antfail2/classes
     [javac] /scratch/simpsons/Scratch/Coding/antfail2/src/Bar.java

BUILD SUCCESSFUL
Total time: 0 seconds
% java -cp classes Foo
Exception in thread "main" java.lang.InstantiationError: Bar
         at Foo.main(Unknown Source)
% touch src/Foo.java
% ant
Buildfile: /scratch/simpsons/Scratch/Coding/antfail2/build.xml

compile:
     [javac] Compiling 1 source file to /scratch/simpsons/Scratch/Coding/antfail2/classes
     [javac] /scratch/simpsons/Scratch/Coding/antfail2/src/Foo.java
     [javac] /scratch/simpsons/Scratch/Coding/antfail2/src/Foo.java:3: error: Bar is abstract; cannot be instantiated
     [javac]     new Bar();
     [javac]     ^
     [javac] 1 error

BUILD FAILED
/scratch/simpsons/Scratch/Coding/antfail2/build.xml:6: Compile failed; see the compiler error output for details.

Total time: 0 seconds



-- 
ss at comp dot lancs dot ac dot uk