NoClassDefFoundError when trying to run DaoGenerator for GreenDAO

问题

I have an Android Project, using Android Studio 2.3, which uses GreenDAO to generate the classes to interact with the SQLite database. The DaoGenerator project always worked before... but today I just needed to add 2 columns/properties to an Entity and whenever I try to run the generator project, I get the following error:

Exception in thread "main" java.lang.NoClassDefFoundError: org/greenrobot/greendao/generator/Schema
    at com.company.daogenerator.ProjectDaoGenerator.main(ProjectDaoGenerator.java:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
Caused by: java.lang.ClassNotFoundException: org.greenrobot.greendao.generator.Schema
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

I'm using GreenDAO 3.2.0 in my application's Gradle file:

compile 'org.greenrobot:greendao:3.2.0'

Also, in DaoGenerator's Gradle file:

apply plugin: 'java'

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'org.greenrobot:greendao-generator:3.2.0'
}

My ProjectDaoGenerator.java file:

package com.company.daogenerator;

import org.greenrobot.greendao.generator.DaoGenerator;
import org.greenrobot.greendao.generator.Entity;
import org.greenrobot.greendao.generator.Property;
import org.greenrobot.greendao.generator.Schema;

public class ProjectDaoGenerator {
    private static Entity primaryKeyEntity;
    private static Entity itemTypeEntity;

    public static void main(String args[]) throws Exception {
        Schema schema = new Schema(1, "com.company.project.datamodel");
        schema.enableKeepSectionsByDefault();

        // Define entities
        Entity primaryKey = schema.addEntity("CDPrimaryKey");
        Entity installation = schema.addEntity("CDInstallation");

        // Z_PRIMARYKEY
        primaryKeyEntity = primaryKey;
        primaryKey.setTableName("Z_PRIMARYKEY");
        primaryKey.addLongProperty("ENT").columnName("Z_ENT").primaryKey();
        primaryKey.addIntProperty("MAX").columnName("Z_MAX");
        primaryKey.addStringProperty("NAME").columnName("Z_NAME");
        primaryKey.addIntProperty("SUPER").columnName("Z_INT");

        // CDInstallation
        installation.setTableName("ZCDINSTALLATION");
        installation.addLongProperty("packageDate").columnName("ZPACKAGEDATE");

        (...) // Other Properties

        // **** Generate Schema ****
        new DaoGenerator().generateAll(schema, "app/src/main/java");
    }
}

It's as if it couldn't find org.greenrobot.greendao.generator.Schema.

回答1:

Set the build.gradle file for your generator like this (especially note the mainClassName):

Then click the "Gradle" tab in the right sidebar of Android Studio and select the "run" task of your daogenerator like this:

It's worked for me , more details check link : https://github.com/greenrobot/greenDAO/issues/619 http://greenrobot.org/greendao/documentation/generator/#Triggering_generation

回答2:

Apart from what @Jesto Paul mentioned, I changed the following in the Generator class

new DaoGenerator().generateAll(schema, "./app/src/main/java"); - shows Path not exist.

new DaoGenerator().generateAll(schema, "../app/src/main/java");

(added double dot for the path). After doing this the generator create the tables to the folder.

回答3:

For some reason, I ran into the same problem after updating android buildToolsVersion.

After some time of searching, i've accidentally checked "Run > Edit Configurations..." for the DaoGenerator-Application.

In the list of JRE "Android API 25 Platform" was selected. So I changed it back to the external Java running on my computer (e.g. "1.8", did it before some days ago). That solved it for me.

Edit: in this project I use GreenDAO 2.1.0

Edit 2:

https://github.com/greenrobot/greenDAO/issues/619 - http://greenrobot.org/greendao/documentation/generator/#Triggering_generation

来源：https://stackoverflow.com/questions/42843031/noclassdeffounderror-when-trying-to-run-daogenerator-for-greendao

标签

android

sqlite

android-studio

greendao