Question

I really have problem with this one.

So I have a jar with a class for handling a database connection. In that class I have put several methods. Out of this class I have created a jar using Ant.

Sometime yesterday I suddenly could not access the latest method in that db class anymore. I get:

compile:
[javac] C:\cygwin\home\user\Dev\Java\avc_alarm\build.xml:22: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
[javac] Compiling 1 source file to C:\cygwin\home\user\Dev\Java\avc_alarm\build
[javac] C:\cygwin\home\user\Dev\Java\avc_alarm\src\se\gefa\avc_alarm\Main.java:9: error: cannot find symbol
[javac] symbolAliases = db.getAlarmSymbolAlias();
[javac]                   ^
[javac]   symbol:   method getAlarmSymbolAlias()
[javac]   location: variable db of type AvcDb
[javac] 1 error

Code that tries to use this class method:

package se.gefa.avc_alarm;

import se.gefa.avc_db.AvcDb;
import java.util.ArrayList;

public class Main {
    static AvcDb db  = new AvcDb();
    static ArrayList<String> symbolAliases;

    public static void main(String args[]) throws Exception {
        db.setupConnection("jdbc:h2:tcp://localhost/C:/XXXX/xyz", "sa", "");
        symbolAliases = db.getAlarmSymbolAlias();
    }
}

And the db class (which goes into a jar):

package se.gefa.avc_db;

import java.sql.*;
import java.util.ArrayList;

public class AvcDb {

    // ---
    // Other methods that DO work
    // ---

    // The one that DO NOT work
    public ArrayList<String> getAlarmSymbolAlias() throws Exception {
        String query = "SELECT * FROM Alarm";
        Statement statement = conn.createStatement();
        ResultSet resultSet = statement.executeQuery(query);

        ArrayList<String> symbols = new ArrayList<String>();
        while (resultSet.next())
            symbols.add(resultSet.getString("symbol_alias"));

        return symbols;
    }
}

I’m using java 7, Ant 1.8.3 and Vim. When opening the db jar in IntelliJ I can see that the getAlarmSymbolAlias method exists. And as I said, I could call any other of the methods for the db class except any method added yesterday. A simple test in IntelliJ and it seems to work (but I don’t want to learn a new Editor when I got all other set up in Vim, CL and Ant.

Edit Ant script:

<project name="AvcAlarm" default="dist" basedir=".">
  <description>
    Alarm program. 
  </description>

  <property name="src" location="src"/>
  <property name="build" location="build"/>
  <property name="dist" location="dist"/>
  <property name="lib" location="lib"/>

  <path id="classpath">
    <fileset dir="${lib}" includes="**/*.jar"/>
  </path>

  <target name="init">
    <tstamp/>
    <mkdir dir="${build}"/>
    <mkdir dir="${dist}"/>
  </target>

  <target name="compile" depends="init" description="compile the source " >
    <javac srcdir="${src}" destdir="${build}" classpathref="classpath"/>
  </target>

  <target name="dist" depends="compile" description="generate the distribution" >
    <jar destfile="${dist}/gefa_alarm.jar" basedir="${build}">
        <zipgroupfileset dir="lib" includes="*.jar" />
        <manifest>
            <attribute name="Main-Class" value="se/gefa/avc_alarm/Main"/>
        </manifest>
    </jar>
  </target>

  <target name="clean" description="clean up" >
    <delete dir="${build}"/>
    <delete dir="${dist}"/>
  </target>
</project>

Answer 1

Your classpath must be wrong, or you use an invalid version of the JAR that doesn’t contain this method.

Updated after investigation with OP: another JAR in the lib folder contained a different version of the AvcDb, and was being loaded first on the classpath, so the desired method could not be found.