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How can I tell my netbeans build.xml where to find my servlets-api.jar?

I am trying to resurrect on old project and get it compiling in netbeans again. Previously - as in 7 years ago - it worked fine but now on a new rig I have to reconfigure everything. The part of the old project I am trying to recompile is just a small java utilities project - not even a full application by itself. The project needs the servlets-api.jar file to compile. The IDE editor works fine - it seems to find it as I get no red lines under the javax.* import line. Only when I try to compile do I get the errors like so:
error: package javax.servlet does not exist
import javax.servlet.ServletException;
My old build script is :
<?xml version="1.0"?>
<project name="javautils" default="package" basedir=".">
<property file="build.properties" />
<path id="classpath">
<pathelement path="classes"/>
<pathelement location="${jdbc.jar}"/>
<pathelement location="${lib.dir}"/>
<pathelement location="${servletjars.home}"/>
</path>
<presetdef name="javac">
<javac includeantruntime="false" />
</presetdef>
<target name="clean">
<delete dir="classes" />
</target>
<target name="prepare">
<mkdir dir="classes" />
</target>
<target name="compile" depends="prepare" description="compile classes">
<javac srcdir="${source.dir}" destdir="${build.dir}">
<classpath refid="classpath" />
</javac>
</target>
<target name="package" depends="compile" description="Packages the web archive file">
<echo message="Packaging ${app.name}'s web archive file ..."/>
<!--
<delete file="${basedir}/${app.name}.war"/>
<jar jarfile="${basedir}/${app.name}.war">
<fileset dir="${basedir}/war" includes="**"/>
</jar>
-->
<jar jarfile="${basedir}/${app.name}.jar">
<fileset dir="${basedir}/classes" includes="**"/>
</jar>
<copy todir="${specialjars.home}">
<fileset dir="${basedir}">
<include name="**/*.jar"/>
</fileset>
</copy>
<copy todir="${standardjars.home}">
<fileset dir="${basedir}">
<include name="**/*.jar"/>
</fileset>
</copy>
</target>
</project>
and my build.properties file is like so:
source.dir=src
build.dir=classes
app.name=JavaUtils
standardjars.home=f:/glassfishv3/glassfish/lib
servletjars.home=f:/glassfishv3/glassfish/modules/javax.servlet.jar
specialjars.home=f:/javaprojects/lib
I know all the servletjars.home path has to be upgraded to point to the tomcat file at C:\Program Files\Apache Software Foundation\Tomcat 8.5\lib\servlets-api.jar but when I do so the compile fails all the same.
I have read a ton of other posts from other users asking the same thing but so far no answers seem address my situation. It has been so long since I did this kind of java programming I have to relearn how to work with some of this stuff.
I am now using windows 10, netbeans 8.2, java 1.8, ant 1.10.1, tomcat 8.5 and MySQL (previously I was using Oracle XE till it crashes and I couldn't revive the DB files).
Please help!

Ant / External libraries

When I'm using external libraries (lucene) and running my java application through eclipse (run application) all works fine with the libs in the classpath.
But when I'm using Ant, i got this error here:
java.lang.ClassNotFoundException: org.apache.lucene.store.Directory
I guess this error shows up, cause of an incorrect classpath. Stange that no compilation error occurs, when ant compiles the code. This is my ant file:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project basedir="." default="build">
<path id="classpath">
<pathelement location="bin"/>
<pathelement location="GUI_P/lucene-6.2.0/lucene-6.2.0/analysis/common/lucene-analyzers-common-6.2.0.jar"/>
<pathelement location="GUI_P/lucene-6.2.0/lucene-6.2.0/core/lucene-core-6.2.0.jar"/>
<pathelement location="GUI_P/lucene-6.2.0/lucene-6.2.0/grouping/lucene-grouping-6.2.0.jar"/>
<pathelement location="GUI_P/lucene-6.2.0/lucene-6.2.0/queryparser/lucene-queryparser-6.2.0.jar"/>
<pathelement location="GUI_P/lucene-6.2.0/lucene-6.2.0/queries/lucene-queries-6.2.0.jar"/>
</path>
<target name="init">
<mkdir dir="bin"/>
<copy includeemptydirs="false" todir="bin">
<fileset dir="src">
<exclude name="**/*.launch"/>
<exclude name="**/*.java"/>
</fileset>
</copy>
</target>
<target depends="init" name="build">
<javac debug="true" destdir="bin" includeantruntime="true">
<src path="src"/>
<classpath refid="classpath"/>
</javac>
</target>
<target name="jar" depends="build">
<mkdir dir="GUI_P"/>
<jar destfile="GUI_P/GUI_P.jar" basedir="bin">
<manifest>
<attribute name="Main-Class" value="gui.Gui"/>
</manifest>
</jar>
</target>
<target name="copySamples" depends="jar">
<copy todir="GUI_P/samples">
<fileset dir="src/gui/samples"/>
</copy>
</target>
</project>
Can you please help me here out?

It's not that strange, because ClassNotFoundException arises always when trying a dynamic instantiation (through Class.forName()). So it is possible that the same classpath produces a right compilation, but it is not complete for an execution: It lacks the dynamic dependencies.
In your case, you must add to the execution classpath the lucene-core library (at least).

Need to make a ant build file for eclipse project

I have a simple game implemented in eclipse. It consists of about 8 classes.
It is for my school assignment.
In the turn in specification, there is written:
"Send me all source codes, documentation and ant build file, which allows the project to be compiled and generate javadoc documentation".
I really do not understand how ant works. I googled some tutorials, but I cannot understand them either. I tried to generate build.xml file in eclipse, but the teacher said that this doesnt work either.
Could someone give me some simple steps or give me link to some really basic tutorial? Thanks for help.
This is the eclipse generated ant (export project as antbuildfile):
And it is kind of weird, because the class BasicPaint I deleted a long time ago.
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- WARNING: Eclipse auto-generated file.
Any modifications will be overwritten.
To include a user specific buildfile here, simply create one in the same
directory with the processing instruction <?eclipse.ant.import?>
as the first entry and export the buildfile again. --><project basedir="." default="build" name="Snakes_and_Adders">
<property environment="env"/>
<property name="debuglevel" value="source,lines,vars"/>
<property name="target" value="1.8"/>
<property name="source" value="1.8"/>
<path id="Snakes_and_Adders.classpath">
<pathelement location="bin"/>
</path>
<target name="init">
<mkdir dir="bin"/>
<copy includeemptydirs="false" todir="bin">
<fileset dir="src">
<exclude name="**/*.java"/>
</fileset>
</copy>
</target>
<target name="clean">
<delete dir="bin"/>
</target>
<target depends="clean" name="cleanall"/>
<target depends="build-subprojects,build-project" name="build"/>
<target name="build-subprojects"/>
<target depends="init" name="build-project">
<echo message="${ant.project.name}: ${ant.file}"/>
<javac debug="true" debuglevel="${debuglevel}" destdir="bin" includeantruntime="false" source="${source}" target="${target}">
<src path="src"/>
<classpath refid="Snakes_and_Adders.classpath"/>
</javac>
</target>
<target description="Build all projects which reference this project. Useful to propagate changes." name="build-refprojects"/>
<target name="BasicPaint">
<java classname="snakes_and_adders.BasicPaint" failonerror="true" fork="yes">
<classpath refid="Snakes_and_Adders.classpath"/>
</java>
</target>
<target name="Game">
<java classname="snakes_and_adders.Game" failonerror="true" fork="yes">
<classpath refid="Snakes_and_Adders.classpath"/>
</java>
</target>
<target name="NewGame">
<java classname="snakes_and_adders.NewGame" failonerror="true" fork="yes">
<classpath refid="Snakes_and_Adders.classpath"/>
</java>
</target>
<target name="PaintingExample">
<java classname="snakes_and_adders.PaintingExample" failonerror="true" fork="yes">
<classpath refid="Snakes_and_Adders.classpath"/>
</java>
</target>

Ant is used to perform tasks that are useful to build applications. You have tasks like <javac> <jar> etc.. To compile your classes and put them in a jar file.
I don't see why the build.xml generated file wouldn't work.. But you can take it as an example to understand how ant works. You can also adapt that build.xml file to make it work anywhere.
This tutorial looks well explained at first sight: http://www.javaworld.com/article/2076208/java-app-dev/automate-your-build-process-using-java-and-ant.html
I find that ant can be pretty complex easily, it'll take you time to understand it well but it's really doable.

Using Cobertura in unix to generate the code coverage reports

I m using cobertura-1.9.4.1 to generate code coverage reports.First I set the classpath to cobertura.jar and to other jars in the lib folder. Then I execute cobertura-instrument.sh.
But on executing I get the error loaded information on 0 classes . I m giving the complete path to the compiled classes still it is unable to instrument the classes .
So, what am I missing or what could be the possible reasons for this.

Do you mean the error is during the instrumentation, or that after running your tests, the coverage still shows zero?
Here's an example of instrumentation (with Ant):
<target name="--coverage.instrument">
<delete file="cobertura.ser"/>
<mkdir dir="${coverage.instrumented.dir}"/>
<cobertura-instrument todir="${coverage.instrumented.dir}">
<fileset dir="${classes.main.dir}">
<include name="**/*.class"/>
<exclude name="**/*Test.class"/>
</fileset>
</cobertura-instrument>
</target>
Don't forget that you need this sysproperty when testing (eg in Ant Junit task):
<sysproperty key="net.sourceforge.cobertura.datafile" file="cobertura.ser"/>
Once Cobertura is set up an instrumentation has happened, an example of execution:
<target name="--test.unit">
<mkdir dir="${temp.dir}/unit-tests"/>
<junit forkmode="perBatch" printsummary="yes" haltonfailure="no" haltonerror="no"
failureproperty="unit.tests.failed">
<sysproperty key="net.sourceforge.cobertura.datafile" file="cobertura.ser"/>
<classpath refid="classpath.test.utest"/>
<formatter type="xml"/>
<batchtest fork="yes" todir="${temp.dir}/unit-tests">
<fileset dir="${java.src.utest.dir}" includes="**/*Test.java"/>
</batchtest>
</junit>
</target>

I believe that recent versions of Cobertura don't work well with JDK5. Strongly suggest upgrading the JDK.

Ant built does not generate class files

I'm using build.xml to build my src. However it failed to generate class files without any error message. The full script is
<?xml version="1.0"?>
<project name="auxiliary" basedir="." default="dist">
<property name="src.dir" value="../auxiliary-src/com/nextbio/drugbank"/>
<property name="dist.dir" value="dist"/>
<property name="lib.dir" value="../jboss_config/common_app_jars"/>
<property name="temp.dir" value="temp"/>
<property name="foo_dist.dir" value="../foo/dist"/>
<path id="libs-classpath">
<fileset dir="${foo_dist.dir}">
<include name="foo.jar"/>
</fileset>
</path>
<target name="dist" depends="auxiliary-dist" />
<target name="auxiliary-cleanup">
<delete dir="${temp.dir}"/>
<delete dir="${dist.dir}"/>
<echo message="cleaned up. ${temp.dir}, and ${dist.dir} have been deleted."/>
</target>
<target name ="auxiliary-dist">
<delete dir="${temp.dir}"/>
<echo message="delete ${temp.dir}" />
<mkdir dir="${temp.dir}"/>
<javac destdir="${temp.dir}" source="1.6" target="1.6" debug="on" fork="true" memorymaximumsize="1024m">
<src path="${src.dir}"/>
<classpath>
<path refid="libs-classpath"/>
</classpath>
<include name="com/car/**"/> <!-- troubled line -->
</javac>
<!--<copy overwrite="true" todir="${temp.dir}">
<fileset dir="${src.dir}">
<exclude name="**/*.java"/>
<exclude name="**/*.sql"/>
<exclude name="**/*.txt"/>
</fileset>
</copy>
<delete dir="${dist.dir}"/>
<mkdir dir="${dist.dir}"/>
<jar destfile="${dist.dir}/auxiliary.jar" basedir="${temp.dir}"/> -->
</target>
There is no class file in ${temp.dir} after this step, and no error message. I double checked it, and found it is because of the "troubled line". I tried to add some files to the classpath. I don't know why it is wrong.

The source path should point to the root of the package tree. You make it point to a specific package inside the sources : ../auxiliary-src/com/nextbio/drugbank.
And in the javac task, you ask it to compile all the files matching the pattern com/car/**. That means that it will compile the Java source files in ../auxiliary-src/com/nextbio/drugbank/com/car or in a subdirectory. If that's the case, you have very unconventional package names.

I had the same problem.
My project complilated well but the classes there weren't in nowhere and It didn't have any error message.
My problem was the classpath. The eclipse wizard added EclipseLink 2.5.1 jars.
I removed it and the problem is gone.
I suggest make a simple HelloWord and remove all jars
reference from the classpath and try again.

I encountered this "ant, javac, compile" problem related with the classpath to.
No debug or verbose message shown.
This behavior appear because in classpath exists not compatible (superior) version jar packages and that cause no output classes.