React Native Android Duplicate file error when generating apk

Remove the files you might have on:

android/app/src/main/res/drawable-mdpi/
android/app/src/main/res/drawable-xhdpi/
android/app/src/main/res/drawable-xxhdpi/

Run Build again, This fixed the issue for me.

Give some tips for you, hope it's work.

Update with "react": "16.7.0", "react-native": "0.57.8"

Custom node_modules/react-native/react.gradle to solve the Duplicate file error perfectly. Add following code into currentBundleTask's creation block (after doFirst block)

doLast {
    def moveFunc = { resSuffix ->
        File originalDir = file("${resourcesDir}/drawable-${resSuffix}");
        if (originalDir.exists()) {
            File destDir = file("$buildDir/../src/main/res/drawable-${resSuffix}");
            ant.move(file: originalDir, tofile: destDir);
        }
    }
    moveFunc.curry("ldpi").call()
    moveFunc.curry("mdpi").call()
    moveFunc.curry("hdpi").call()
    moveFunc.curry("xhdpi").call()
    moveFunc.curry("xxhdpi").call()
    moveFunc.curry("xxxhdpi").call()
}

---

You can create script to do it automatically.

1. Create android-react-gradle-fix file
2. Create script android-release-gradle-fix.js file

3. Update package.json file:

   "scripts": { "postinstall": "node ./android-release-gradle-fix.js" },

That's it! Run npm install to get awesome.

Note: If you run npm install on ci like jenkins, you may get error: postinstall: cannot run in wd %s %s (wd=%s) node => just use npm install --unsafe-perm instead

At the time of writing, the more recent versions of React Native (>0.57.0) have increased the Gradle wrapper level to 4.4 and Gradle plugin to 3.1.4, as indicated by the changelog. This has the effect of making the Gradle build process store the results of AAPT, which are now required, within a different directory than previously.

In terms of Nhan Cao's awesome workaround, we need to make a slight modification to prevent duplicate resource collisions, since it looks to be pointed at the old directory and not the app's generated directory. By changing the target directory where these duplicate files are merged together after the resources have been generated, we can still dedup the resources.

The existing react.gradle refers to the path below:

$buildDir === <project-working-directory>/android/app/build

The duplicate file paths can appear between:

file("$buildDir/../src/main/res/drawable-${resSuffix}")
file("$buildDir/generated/res/react/release/drawable-${resSuffix}")

As a workaround, we can update Nhan's solution as follows (be sure to include this within the currentBundleTask after the declaration of doFirst in react.gradle:

doLast {
    def moveFunc = { resSuffix ->
        File originalDir = file("$buildDir/generated/res/react/release/drawable-${resSuffix}");
        if (originalDir.exists()) {
            File destDir = file("$buildDir/../src/main/res/drawable-${resSuffix}");
            ant.move(file: originalDir, tofile: destDir);
        }
    }
    moveFunc.curry("ldpi").call()
    moveFunc.curry("mdpi").call()
    moveFunc.curry("hdpi").call()
    moveFunc.curry("xhdpi").call()
    moveFunc.curry("xxhdpi").call()
    moveFunc.curry("xxxhdpi").call()
}

If your app depends on /raw assets too, the method outlined below should help you:

doLast {
    def moveFunc = { resSuffix ->
        File originalDir = file("$buildDir/generated/res/react/release/${resSuffix}");
        if (originalDir.exists()) {
            File destDir = file("$buildDir/../src/main/res/${resSuffix}");
            ant.move(file: originalDir, tofile: destDir);
        }
     }
     moveFunc.curry("drawable-ldpi").call()
     moveFunc.curry("drawable-mdpi").call()
     moveFunc.curry("drawable-hdpi").call()
     moveFunc.curry("drawable-xhdpi").call()
     moveFunc.curry("drawable-xxhdpi").call()
     moveFunc.curry("drawable-xxxhdpi").call()
     moveFunc.curry("raw").call()
}

If your app also uses custom "build types" other than release, such as preRelease or stagingRelease(Android Gradle Plugin allows you to define them in build.gradle), you should change originalDir variable like below:

# from
File originalDir = file("$buildDir/generated/res/react/release/drawable-${resSuffix}");
# to 
File originalDir = file("$buildDir/generated/res/react/${targetName}/drawable-${resSuffix}");