Gradle - Error Could not find method implementation() for arguments

Know the implementation method

You'll find the implementation() function as an upgrade over 'compile'. It was introduced in the Gradle 3.0.0 plugin. Always use it in the build.gradle file typically located at android/app/build.gradle. This move fosters rapid build performance and on-the-fly resource loading.

With the advent of 'implementation', the 'compile' keyword was marked deprecated and is scheduled for removal after 2018. Witnessing this error means your project needs an upgrade.

Leveraging the java-library plugin

For Java libraries, engaging the "java-library" plugin introduces added functionality. This plugin distinguishes API versus implementation dependencies, optimizing your build process. See the plugin addition to your build.gradle here:

apply plugin: 'java-library'  // Hitching a free ride with extra features! 
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Nest your dependencies with 'api' or 'implementation' based on your exposure needs. You'll uncover more by visiting the plugin's documentation.

Syncing your project

After above adjustments, ensure a quick project sync with Gradle files. In some cases, your project level build.gradle might require 'classpath' update to mirror the new Gradle plugin version:

buildscript {
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.0' // The 'New Normal' for Gradle!
    }
}
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If your Gradle version is old, updating it in the gradle-wrapper.properties works magic:

distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip
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Handling version disagreements

You may encounter version conflicts following an upgrade. Here, the resolutionStrategy feature of Gradle shines. It helps enforce certain library versions:

configurations.all {
    resolutionStrategy.force 'com.android.support:support-v4:27.1.0' // When you mean business!
}
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Also, ensure version alignment of your support libraries. A appcompat-v7:26.0.0 for instance should coincide with other support libraries versions.

Dealing with caching issues

At times after updating, Gradle clings to the old configuration owing to caching. Clearing the cache remedially paves the way:

./gradlew cleanBuildCache  // Goodbye old, hello new!
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Now, outdated dependencies step aside for current versions.

Tuning Gradle properties

Power users can enhance performance by tuning gradle.properties. For instance, enabling the daemon can reduce build times, or tweaking Java's memory settings can induce optimization:

org.gradle.daemon=true    // The speedy Gonzales of Gradle!
org.gradle.jvmargs=-Xmx1536m  // Feed the 'memory monster' right!
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Mixed-language project considerations

For mixed Kotlin and Java code projects, ensure both java and kotlin-android plugins are applied. This guarantees smooth interoperability and gradle project sync process:

apply plugin: 'java'
apply plugin: 'kotlin-android'  // Cosmic couple for Android devs!
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