Unable to build apk: The number of method references cannot exceed 64K
<p>I have been trying to build the apk file for my app, however, I am getting the error: The number of method references cannot exceed 64K.</p>

<p>Here are the errors,</p>

<p>Error:The number of method references in a .dex file cannot exceed 64K.
Learn how to resolve this issue at <a href="https://developer.android.com/tools/building/multidex.html" rel="noreferrer">https://developer.android.com/tools/building/multidex.html</a></p>

<p>Error:Execution failed for task ':app:transformClassesWithDexForDebug'.</p>

<blockquote>
  <p>com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.7.0_15\bin\java.exe'' finished with non-zero exit value 2</p>
</blockquote>

<p>This is my gradle file,</p>

<pre><code>apply plugin: 'com.android.application'

android {
compileSdkVersion 23
buildToolsVersion "23.0.3"

defaultConfig {
    applicationId "nikhilraghavendra.hopper"
    minSdkVersion 21
    targetSdkVersion 23
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        shrinkResources true
        minifyEnabled true
        useProguard true
        proguardFiles getDefaultProguardFile('proguard-android.txt'),
                'proguard-rules.pro'
    }
}
packagingOptions {
    exclude 'META-INF/LICENSE'
    exclude 'META-INF/LICENSE-FIREBASE.txt'
    exclude 'META-INF/NOTICE'
}
}

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.2.1'
compile 'com.android.support:design:23.2.1'
compile 'com.google.android.gms:play-services-identity:8.4.0'
compile 'com.firebase:firebase-client-android:2.3.1'
compile 'com.android.support:cardview-v7:23.2.1'
compile 'com.google.android.gms:play-services:8.4.0'
}
</code></pre>

<p>I want to build the apk file and deploy it without any issues, how do I do it?</p>

<p><strong>Update</strong></p>

<p>I also tried the following</p>

<pre><code>apply plugin: 'com.android.application'

android {
compileSdkVersion 23
buildToolsVersion "23.0.3"

dexOptions {
    maxProcessCount = 4 // this is the default value
}

dataBinding{
    enabled = true
}

defaultConfig {
    applicationId "nikhilraghavendra.hopper"
    minSdkVersion 21
    targetSdkVersion 23
    resConfigs "en", "fr"
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        shrinkResources true
        minifyEnabled true
        useProguard true
        proguardFiles getDefaultProguardFile('proguard-android.txt'),
                'proguard-rules.pro'
    }
    debug {
        minifyEnabled true
        useProguard false
    }
}
packagingOptions {
    exclude 'META-INF/LICENSE'
    exclude 'META-INF/LICENSE-FIREBASE.txt'
    exclude 'META-INF/NOTICE'
}
}

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.2.1'
compile 'com.android.support:design:23.2.1'
compile 'com.google.android.gms:play-services-identity:8.4.0'
compile 'com.firebase:firebase-client-android:2.3.1'
compile 'com.android.support:cardview-v7:23.2.1'
compile 'com.google.android.gms:play-services:8.4.0'
}
</code></pre>

<p>This is producing the message:</p>

<p>Error:Execution failed for task ':app:transformClassesWithNewClassShrinkerForDebug'.</p>

<blockquote>
  <p>Warnings found during shrinking, please use -dontwarn or -ignorewarnings to suppress them.</p>
</blockquote>

<p>How do I deal with this and build a proper apk? Please Help.</p>