As of now (May 2014) if you use the default generated project it is actually amazingly simple (though difficult to find instructions!

Open the second level build.gradle, and add the following line to the dependencies {:

compile "commons-io:commons-io:+"

That will get the latest version of commons-io. My complete file looks like this:

apply plugin: 'android'

android {
    compileSdkVersion 19
    buildToolsVersion "19.0.0"

    defaultConfig {
        minSdkVersion 18
        targetSdkVersion 19
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            runProguard false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

dependencies {
    compile "commons-io:commons-io:+"
}

I don't see any problems with your Gradle script, so at first glance, I'm thinking of two possible explanations:

• you import a class that cannot be found in the artifact (e.g. a previous version of commons-io deprecated it and now they removed it)
• your project's structure is set up incorrectly

I copied the exact contents of your script in a build.gradle file, created a src/main/java directory structure in the same directory, and wrote a small application Main.java under that directory with the following:

import org.apache.commons.io.IOCase;

public class Main {
    public static void main(String[] args) {
        System.out.println(IOCase.SENSITIVE.checkEndsWith("abcd1234", "1234"));
    }
}

The code compiles successfully, so I need more context to troubleshoot your problem.