json - NoClassDefFoundError using Jackson 2.2.x on Android with Gradle

Question

For my Android project I set up Gradle with Jackson 2.2.x as follows:

// build.gradle
buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.6.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 18
    buildToolsVersion "18.1.0"

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 18
    }
}

dependencies {
    compile 'com.android.support:appcompat-v7:18.0.0'
    compile 'com.android.support:support-v4:18.0.0'
    compile 'com.google.android.gms:play-services:3.1.36'
    compile 'com.fasterxml.jackson.core:jackson-databind:2.2.+'
    compile 'com.fasterxml.jackson.core:jackson-core:2.2.+'
    compile 'com.fasterxml.jackson.core:jackson-annotations:2.2.+'
}

I simply use the ObjectMapper here:

import com.fasterxml.jackson.databind.ObjectMapper;

// ...

ObjectMapper objectMapper = new ObjectMapper();
try {
    Content content = objectMapper.readValue(inputStream, Content.class);
} catch (IOException e) {
    e.printStackTrace();
}

When I run gradle installDebug and launch the relevant part of the application it crashes:

java.lang.NoClassDefFoundError: com.fasterxml.jackson.databind.ObjectMapper

---

Thoughts:

• I noticed that in the error message com.fasterxml.jackson... is mentioned while com.fasterxml.jackson.core is defined in build.gradle. Is there a mismatch causing the problem?
• I temporarily moved the dependencies block into the android block since I found other build.gradle configurations structured this way. However it seems to make no difference.

Answer 1

Gradle and Android don't always place nicely with dependencies(yet). Running

 gradle clean

seems to fix most problems for me.

Note: If that didn't work, you can run

dexdump classes.dex | grep 'Class descriptor'

on the classes.dex file in the APK. That will check to see if the class is included in the classes.dex file. (Sometimes it's useful if you want to double check whats going on).