Jar Can't Find Main Method - Connected to main class, but can't access method.

Question

Hey everyone!

I've been working on a project in Eclipse and everything's been going smooth except for some Ant issues along the way.

My code compiles perfectly and does exactly what I want it to do, but, when it's in a jar, I get the error:

Exception in thread "main" java.lang.NoSuchMethodError: main

Main definitely exists in the file, so my guess is that it has to do with the way the file is constructed. I've been using SuperCSV to read some excel sheets I have and have constructed my main class around the example from the website: http://supercsv.sourceforge.net/codeExamples_general.html. Here's my adaptation:

ExcelFile.java

package jab.jm.main;

import jab.jm.readers.FileManager;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.net.URL;

import junit.framework.Test;

import org.supercsv.cellprocessor.constraint.StrMinMax;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanReader;
import org.supercsv.io.ICsvBeanReader;
import org.supercsv.prefs.CsvPreference;

class ReadingObjects {

    static final CellProcessor[] userProcessors = { null,
            new StrMinMax(0, 100), null, new StrMinMax(0, 100), null,
            new StrMinMax(0, 100), null, null, null, null, null, null, null,
            null, null, null, null, null, null, null, null, null, null, null,
            null, null, null, null, null, new StrMinMax(0, 100), null,
            new StrMinMax(0, 100), null, null, null, null, null, null, null,
            null, null, null, null, null, null, null, null, null, null, null,
            null, null, null, null, null, null, null, null, null };


    public static void main(String[] args) throws Exception {
        ICsvBeanReader inFile = new CsvBeanReader(
                new FileReader(
                        "C:\\Users\\Justian\\workspaces\\LNConnectionCompiler\\src\\jab\\jm\\main\\Fred_Jewell.csv"),
                CsvPreference.EXCEL_PREFERENCE);
        try {
            final String[] header = { "title", "firstName", "middleName",
                    "lastName", "suffix", "email", "email2", "email3",
                    "businessStreet", "businessStreet2", "businessStreet3",
                    "businessCity", "businessState", "businessPostalCode",
                    "businessCountry", "homeStreet", "homeStreet2",
                    "homeStreet3", "homeCity", "homeState", "homePostalCode",
                    "homeCountry", "otherStreet", "otherStreet2",
                    "otherStreet3", "otherCity", "otherState",
                    "otherPostalCode", "otherCountry", "company", "department",
                    "jobTitle", "assistantPhone", "businessFax",
                    "businessPhone", "businessPhone2", "callback", "carPhone",
                    "companyMainPhone", "homeFax", "homePhone", "homePhone2",
                    "isdn", "mobilePhone", "otherFax", "otherPhone", "pager",
                    "primaryPhone", "radioPhone", "TTYTTDPhone", "telex",
                    "assistantName", "birthday", "managerName", "notes",
                    "otherPOBox", "spouse", "webPage", "personalWebPage" };
            ExcelFile file;
            while ((file = inFile.read(ExcelFile.class, header, userProcessors)) != null) {
                if (file.getCompany().indexOf("Jabian") >= 0)
                    System.out.println(file.getFirstName() + " " + file.getLastName());
            }
        } finally {
            inFile.close();
        }

        URL location = ExcelFile.class.getProtectionDomain().getCodeSource().getLocation();
        System.out.println(location.getFile());

    }
}

public class ExcelFile {
    private String title, firstName, middleName, lastName, suffix, email,
            email2, email3, businessStreet, businessStreet2, businessStreet3,
            businessCity, businessState, businessPostalCode, businessCountry,
            homeStreet, homeStreet2, homeStreet3, homeCity, homeState,
            homePostalCode, homeCountry, otherStreet, otherStreet2,
            otherStreet3, otherCity, otherState, otherPostalCode, otherCountry,
            company, department, jobTitle, assistantPhone, businessFax,
            businessPhone, businessPhone2, callback, carPhone,
            companyMainPhone, homeFax, homePhone, homePhone2, isdn,
            mobilePhone, otherFax, otherPhone, pager, primaryPhone, radioPhone,
            TTYTTDPhone, telex, assistantName, birthday, managerName, notes,
            otherPOBox, spouse, webPage, personalWebPage;

    public String getTitle() {
        return title;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getMiddleName() {
        return middleName;
    }

    public String getLastName() {
        return lastName;
    }

    public String getSuffix() {
        return suffix;
    }

    public String getEmail() {
        return email;
    }

    public String getEmail2() {
        return email2;
    }

    public String getEmail3() {
        return email3;
    }

    public String getBusinessStreet() {
        return businessStreet;
    }

    public String getBusinessStreet2() {
        return businessStreet2;
    }

    public String getBusinessStreet3() {
        return businessStreet3;
    }

    public String getBusinessCity() {
        return businessCity;
    }

    public String getBusinessState() {
        return businessState;
    }

    public String getBusinessPostalCode() {
        return businessPostalCode;
    }

    public String getBusinessCountry() {
        return businessCountry;
    }

    public String getHomeStreet() {
        return homeStreet;
    }

    public String getHomeStreet2() {
        return homeStreet2;
    }

    public String getHomeStreet3() {
        return homeStreet3;
    }

    public String getHomeCity() {
        return homeCity;
    }

    public String getHomeState() {
        return homeState;
    }

    public String getHomePostalCode() {
        return homePostalCode;
    }

    public String getHomeCountry() {
        return homeCountry;
    }

    public String getOtherStreet() {
        return otherStreet;
    }

    public String getOtherStreet2() {
        return otherStreet2;
    }

    public String getOtherStreet3() {
        return otherStreet3;
    }

    public String getOtherCity() {
        return otherCity;
    }

    public String getOtherState() {
        return otherState;
    }

    public String getOtherPostalCode() {
        return otherPostalCode;
    }

    public String getOtherCountry() {
        return otherCountry;
    }

    public String getCompany() {
        return company;
    }

    public String getDepartment() {
        return department;
    }

    public String getJobTitle() {
        return jobTitle;
    }

    public String getAssistantPhone() {
        return assistantPhone;
    }

    public String getBusinessFax() {
        return businessFax;
    }

    public String getBusinessPhone() {
        return businessPhone;
    }

    public String getBusinessPhone2() {
        return businessPhone2;
    }

    public String getCallBack() {
        return callback;
    }

    public String getCarPhone() {
        return carPhone;
    }

    public String getCompanyMainPhone() {
        return companyMainPhone;
    }

    public String getHomeFax() {
        return homeFax;
    }

    public String getHomePhone() {
        return homePhone;
    }

    public String getHomePhone2() {
        return homePhone2;
    }

    public String getISDN() {
        return isdn;
    }

    public String getMobilePhone() {
        return mobilePhone;
    }

    public String getOtherFax() {
        return otherFax;
    }

    public String getOtherPhone() {
        return otherPhone;
    }

    public String getPager() {
        return pager;
    }

    public String getPrimaryPhone() {
        return primaryPhone;
    }

    public String getRadioPhone() {
        return radioPhone;
    }

    public String getTTYTTDPhone() {
        return TTYTTDPhone;
    }

    public String getTelex() {
        return telex;
    }

    public String getAssistantName() {
        return assistantName;
    }

    public String getBirthday() {
        return birthday;
    }

    public String getManagerName() {
        return managerName;
    }

    public String getNotes() {
        return notes;
    }

    public String getOtherPOBox() {
        return otherPOBox;
    }

    public String getSpouse() {
        return spouse;
    }

    public String getWebPage() {
        return webPage;
    }

    public String getPersonalWebPage() {
        return personalWebPage;
    }

    public void setTitle(final String title) {
        this.title = title;
    }

    public void setFirstName(final String firstName) {
        this.firstName = firstName;
    }

    public void setMiddleName(final String middleName) {
        this.middleName = middleName;
    }

    public void setLastName(final String lastName) {
        this.lastName = lastName;
    }

    public void setSuffix(final String suffix) {
        this.suffix = suffix;
    }

    public void setEmail(final String email) {
        this.email = email;
    }

    public void setEmail2(final String email2) {
        this.email2 = email2;
    }

    public void setEmail3(final String email3) {
        this.email3 = email3;
    }

    public void setBusinessStreet(final String businessStreet) {
        this.businessStreet = businessStreet;
    }

    public void setBusinessStreet2(final String businessStreet2) {
        this.businessStreet2 = businessStreet2;
    }

    public void setBusinessStreet3(final String businessStreet3) {
        this.businessStreet3 = businessStreet3;
    }

    public void setBusinessCity(final String businessCity) {
        this.businessCity = businessCity;
    }

    public void setBusinessState(final String businessState) {
        this.businessState = businessState;
    }

    public void setBusinessPostalCode(final String businessPostalCode) {
        this.businessPostalCode = businessPostalCode;
    }

    public void setBusinessCountry(final String businessCountry) {
        this.businessCountry = businessCountry;
    }

    public void setHomeStreet(final String homeStreet) {
        this.homeStreet = homeStreet;
    }

    public void setHomeStreet2(final String homeStreet2) {
        this.homeStreet2 = homeStreet2;
    }

    public void setHomeStreet3(final String homeStreet3) {
        this.homeStreet3 = homeStreet3;
    }

    public void setHomeCity(final String homeCity) {
        this.homeCity = homeCity;
    }

    public void setHomeState(final String homeState) {
        this.homeState = homeState;
    }

    public void setHomePostalCode(final String homePostalCode) {
        this.homePostalCode = homePostalCode;
    }

    public void setHomeCountry(final String homeCountry) {
        this.homeCountry = homeCountry;
    }

    public void setOtherStreet(final String otherStreet) {
        this.otherStreet = otherStreet;
    }

    public void setOtherStreet2(final String otherStreet2) {
        this.otherStreet2 = otherStreet2;
    }

    public void setOtherStreet3(final String otherStreet3) {
        this.otherStreet3 = otherStreet3;
    }

    public void setOtherCity(final String otherCity) {
        this.otherCity = otherCity;
    }

    public void setOtherState(final String otherState) {
        this.otherState = otherState;
    }

    public void setOtherPostalCode(final String otherPostalCode) {
        this.otherPostalCode = otherPostalCode;
    }

    public void setOtherCountry(final String otherCountry) {
        this.otherCountry = otherCountry;
    }

    public void setCompany(final String company) {
        this.company = company;
    }

    public void setDepartment(final String department) {
        this.department = department;
    }

    public void setJobTitle(final String jobTitle) {
        this.jobTitle = jobTitle;
    }

    public void setAssistantPhone(final String assistantPhone) {
        this.assistantPhone = assistantPhone;
    }

    public void setBusinessFax(final String businessFax) {
        this.businessFax = businessFax;
    }

    public void setBusinessPhone(final String businessPhone) {
        this.businessPhone = businessPhone;
    }

    public void setBusinessPhone2(final String businessPhone2) {
        this.businessPhone2 = businessPhone2;
    }

    public void setCallback(final String callback) {
        this.callback = callback;
    }

    public void setCarPhone(final String carPhone) {
        this.carPhone = carPhone;
    }

    public void setCompanyMainPhone(final String companyMainPhone) {
        this.companyMainPhone = companyMainPhone;
    }

    public void setHomeFax(final String homeFax) {
        this.homeFax = homeFax;
    }

    public void setHomePhone(final String homePhone) {
        this.homePhone = homePhone;
    }

    public void setHomePhone2(final String homePhone2) {
        this.homePhone2 = homePhone2;
    }

    public void setIsdn(final String isdn) {
        this.isdn = isdn;
    }

    public void setMobilePhone(final String mobilePhone) {
        this.mobilePhone = mobilePhone;
    }

    public void setOtherFax(final String otherFax) {
        this.otherFax = otherFax;
    }

    public void setOtherPhone(final String otherPhone) {
        this.otherPhone = otherPhone;
    }

    public void setPager(final String pager) {
        this.pager = pager;
    }

    public void setPrimaryPhone(final String primaryPhone) {
        this.primaryPhone = primaryPhone;
    }

    public void setRadioPhone(final String radioPhone) {
        this.radioPhone = radioPhone;
    }

    public void setTTYTTDPhone(final String TTYTTDPhone) {
        this.TTYTTDPhone = TTYTTDPhone;
    }

    public void setTelex(final String telex) {
        this.telex = telex;
    }

    public void setAssistantName(final String assistantName) {
        this.assistantName = assistantName;
    }

    public void setBirthday(final String birthday) {
        this.birthday = birthday;
    }

    public void setManagerName(final String managerName) {
        this.managerName = managerName;
    }

    public void setNotes(final String notes) {
        this.notes = notes;
    }

    public void setOtherPOBox(final String otherPOBox) {
        this.otherPOBox = otherPOBox;
    }

    public void setSpouse(final String spouse) {
        this.spouse = spouse;
    }

    public void setWebPage(final String webPage) {
        this.webPage = webPage;
    }

    public void setPersonalWebPage(final String personalWebPage) {
        this.personalWebPage = personalWebPage;
    }

}

This, in my mind, is a poor construction, but it is entirely possible and that's why I don't run into any issues compiling. Of course, because it's such an unusual construction, Ant may be having trouble trying to access it.

Note that ExcelFile.Java contains the non-public class ReadingObjects, which contains the main method. My theory is that, because ExcelFile.java isn't necessarily THE class that contains the main method, I'm running into issues

Let me know what you guys think. I'm willing to give things a shot.

Many thanks in advance!

-Justian

EDIT: Here is my build file:

<?xml version="1.0" ?>

<project name="ServerJar" default="dist" basedir=".">
    <description>
        Builds client files into .jar
    </description>
    <!-- [build variables] -->
    <property name="src" location="src" />
    <property name="build" location="build" />
    <property name="dist" location="dist" />
    <property name="lib" location="lib" />
    <!-- [path to packages] -->
    <path id="master-classpath">
        <fileset dir="${lib}">
            <include name="*.jar"/>
        </fileset>
    </path>


    <target name="init">
        <!-- makes time stamp to be used in jar name -->
        <tstamp />
        <!-- creates build directory structure -->
        <mkdir dir="${build}" />
    </target>

    <target name="compile" depends="init" description="Compiles the source">
        <!-- compiles the java code from ${src} into ${build} -->
        <!-- <javac srcdir="${src}" destdir="${build}" /> -->
        <javac destdir= "${build}">
            <src path="${src}"/>
            <classpath refid="master-classpath"/>
        </javac>
    </target>

    <target name="dist" depends="compile" description="Generates distributable">
    <!-- creates the distribution directory -->
        <mkdir dir="${dist}/lib" />

        <!-- puts everything in ${build} into the jar file -->
        <jar jarfile="${dist}/lib/CC-${DSTAMP}.jar" basedir="${build}">
            <manifest>
                <attribute name="Main-Class" value="jab.jm.main.ExcelFile" />
            </manifest>
        </jar>

        <!-- makes a jar file for quick test execution -->
        <jar jarfile="${dist}/lib/CC.jar" basedir="${build}">
            <manifest>
                <attribute name="Main-Class" value="jab.jm.main.ExcelFile" />
            </manifest>
        </jar>
    </target>

    <target name="clean" description="Cleans up the extra build files">
        <!-- deletes the ${build} and ${dist} directories -->
        <delete dir="${build}" />
        <delete dir="${dist}" />
    </target>
</project>

EDIT: No Luck on anything. Maybe we can look into reorganizing my one file into two?

I'm a little nervous about that because I don't know what kind of format SuperCSV requires.

Answer 1

Make sure you have the following entry in your Manifest file:

Main-Class: com.yourcompany.ReadingObjects

After that, you will need to run you program like this:

$ java -jar nameofyourjar.jar

Other possibility includes running your program like this (with no need of Manifest change):

$ java -cp nameofyourjar.jar com.yourcompany.ReadingObjects

Regards.

Answer 2

However you are building, you will end up with a META-INF/MANIFEST.MF in your JAR. That file – extract it to see what it contains – needs to have a Main-Class entry in it for the JAR to be executable (so java can know what class to start executing from, of course). The class that is marked as a main class can have any visibility – I tend to prefer to make them public – and the method must be both public and static.

Now for the other, important gotcha. You need to package all your dependencies in your executable JAR file as you can't put things located outside the JAR on the classpath. (You could use another class-loader and dynamic loading tricks, but that's an entirely different level of hairiness.) It's when you start to get into this sort of thing that Maven starts to look a little less overwhelming…

Answer 3

your main method is actually on the ReadingObjects class, and that class needs to be public as well. the manifest line should be:

Main-Class: package jab.jm.main.ReadingObjects

Here are detailed instructions and a working ANT file to do just what you are trying to do. Build an Executable .jar file

After studying your code again, I think the source file should be called ReadingObjects.java, ReadingObjects Class should be public and everything will work as you want it.

Answer 4

The -cp (and -classpath) arguments are ignored when using -jar argument. You need to specify it in the Class-Path attribute of JAR's MANIFEST.MF file.

My ant is a bit rusty, but it's something like those lines:

<attribute name="Class-Path" value="${dist.classpath}"/>

---

Update as per your comments you'd like to know how to do this directly with Eclipse instead of hassling with Ant. First, you need to run the proposed main() method using Ctrl+F11 and then rightclick the project, choose Export > Runnable JAR file (note "Runnable" part, this is important!). Then, in the Wizard you have to choose the same Launch configuration from the list (and if necessary choose library handling) and then click Finish. This way Eclipse will take the buildpath details automagically into account when generating the MANIFEST file.

Answer 5

You could also create a runnable jar in eclipse rather than an Ant build, it will ask you which file holds the main, it usually finds the correct one. You should then select, if I remember correctly, package contents into .jar file.