Cannot create APK with Android Studio when using ProGuard minification

Question

I have a problem creating the APK of my apps.

If I debug / run the application, it works fine. But when I try to generate the corresponding APK, Android Studio gives me a lot of warnings and one error:

Note: there were 159 duplicate class definitions. (http://proguard.sourceforge.net/manual/troubleshooting.html#duplicateclass) Warning:com.thoughtworks.xstream.converters.reflection.CGLIBEnhancedConverter$ReverseEngineeredCallbackFilter: can't find superclass or interface net.sf.cglib.proxy.CallbackFilter Warning:org.apache.harmony.awt.datatransfer.DataProxy: can't find superclass or interface java.awt.datatransfer.Transferable Warning:org.apache.harmony.awt.datatransfer.NativeClipboard: can't find superclass or interface java.awt.datatransfer.Clipboard Warning:library class android.content.res.XmlResourceParser extends or implements program class org.xmlpull.v1.XmlPullParser Warning:library class org.apache.http.auth.AuthenticationException extends or implements program class org.apache.http.ProtocolException [...] Warning:library class org.apache.http.impl.conn.LoggingSessionOutputBuffer extends or implements program class org.apache.http.io.SessionOutputBuffer Warning:com.itextpdf.testutils.ITextTest: can't find referenced class javax.management.OperationsException Warning:com.itextpdf.text.pdf.BarcodeCodabar: can't find referenced class java.awt.Color [...] Warning:com.itextpdf.text.pdf.security.MakeXmlSignature: can't find referenced class javax.xml.crypto.dsig.spec.C14NMethodParameterSpec [...] Warning:com.sun.mail.handlers.image_gif: can't find referenced class java.awt.datatransfer.DataFlavor [...] Warning:com.sun.mail.imap.protocol.IMAPSaslAuthenticator: can't find referenced class javax.security.sasl.Sasl [...] Warning:com.thoughtworks.xstream.converters.extended.ColorConverter: can't find referenced class java.awt.Color [...] Warning:org.apache.harmony.awt.ContextStorage: can't find referenced class java.awt.Toolkit [...] Warning:org.spongycastle.jce.provider.X509LDAPCertStoreSpi: can't find referenced class javax.naming.directory.InitialDirContext [...] Warning:library class android.content.Intent depends on program class org.xmlpull.v1.XmlPullParser [...] Warning:library class org.apache.http.client.HttpClient depends on program class org.apache.http.HttpResponse [...] Warning:library class org.xmlpull.v1.XmlPullParserFactory depends on program class org.xmlpull.v1.XmlPullParser Warning:there were 1077 unresolved references to classes or interfaces. You may need to add missing library jars or update their versions. If your code works fine without the missing classes, you can suppress the warnings with '-dontwarn' options. (http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedclass) Warning:there were 141 instances of library classes depending on program classes. You must avoid such dependencies, since the program classes will be processed, while the library classes will remain unchanged. (http://proguard.sourceforge.net/manual/troubleshooting.html#dependency) Warning:there were 5 unresolved references to program class members. Your input classes appear to be inconsistent. You may need to recompile the code. (http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedprogramclassmember) :vet:proguardInternalRelease FAILED Error:Execution failed for task ':PROJECTNAME:proguardInternalRelease'. > java.io.IOException: Please correct the above warnings first. Information:BUILD FAILED Information:Total time: 13.878 secs Information:1 error Information:679 warnings Information:See complete output in console 

A project is formed from a library project imported as an external project, similar to this in settings.gradle :

 include ':library' project(':library').projectDir = new File(settingsDir, '../Library/library') 

with all the dependencies.

build.gradle library

 apply plugin: 'com.android.library' android { compileSdkVersion 21 buildToolsVersion "21.1.2" defaultConfig { minSdkVersion 15 targetSdkVersion 21 multiDexEnabled true } packagingOptions { exclude 'META-INF/DEPENDENCIES' exclude 'META-INF/NOTICE' exclude 'META-INF/LICENSE' exclude 'META-INF/LICENSE.txt' exclude 'META-INF/NOTICE.txt' } } dependencies { compile 'com.google.android.gms:play-services:+' compile 'com.android.support:support-v13:21.0.+' compile 'com.android.support:multidex:1.0.0' compile('ch.acra:acra:4.5.0') { exclude group: 'org.json' } compile 'org.apache.httpcomponents:httpcore:4.3' compile('org.apache.httpcomponents:httpmime:4.3.1') { exclude group: 'org.apache.httpcomponents', module: 'httpcore' exclude group: 'org.apache.httpcomponents', module: 'httpclient' } compile('javax.mail:mail:1.4.7') { exclude module: 'activation' } compile 'com.madgag.spongycastle:pkix:1.50.0.0' compile 'org.ccil.cowan.tagsoup:tagsoup:1.2.1' compile ('com.itextpdf.tool:xmlworker:5.5.1'){ exclude module: 'itextpdf' } compile('com.thoughtworks.xstream:xstream:1.4.4') { exclude group: 'xmlpull', module: 'xmlpull' } compile 'com.google.zxing:core:3.0.1' compile files('libs/activation.jar') compile files('libs/additionnal.jar') compile files('libs/miniTemplator.jar') compile files('libs/itextg-5.5.1.jar') } 

and the build.gradle project is

 apply plugin: 'com.android.application' android { compileSdkVersion 21 buildToolsVersion "21.1.2" defaultConfig { applicationId "my.package.name" minSdkVersion 15 targetSdkVersion 21 multiDexEnabled true } buildTypes { release { minifyEnabled true proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } productFlavors { def BOOLEAN = "boolean" def TRUE = "true" def FALSE = "false" def A_FIELD= "A_FIELD" internal { buildConfigField BOOLEAN, A_FIELD, FALSE } official { buildConfigField BOOLEAN, A_FIELD, TRUE } } packagingOptions { exclude 'META-INF/DEPENDENCIES' exclude 'META-INF/NOTICE' exclude 'META-INF/LICENSE' exclude 'META-INF/LICENSE.txt' exclude 'META-INF/NOTICE.txt' } } dependencies { compile project(':library') } afterEvaluate { tasks.matching { it.name.startsWith('dex') }.each { dx -> if (dx.additionalParameters == null) { dx.additionalParameters = [] } dx.additionalParameters += '--multi-dex' } } 

How to do this so that the APK can be compiled?

EDIT: after adding a lot of -dontwarn options to proguard-rules.pro, I still got an error, and I cannot resolve these warnings ( There are some tips here, but not for these warnings ...):

 Warning:com.itextpdf.text.pdf.security.PdfPKCS7: can't find referenced method 'ASN1Integer(int)' in program class org.spongycastle.asn1.ASN1Integer Warning:com.sun.activation.viewers.ImageViewer: can't find referenced method 'java.awt.Component add(java.awt.Component)' in program class com.sun.activation.viewers.ImageViewer Warning:com.sun.activation.viewers.ImageViewer: can't find referenced method 'java.awt.Toolkit getToolkit()' in program class com.sun.activation.viewers.ImageViewer Warning:com.sun.activation.viewers.ImageViewer: can't find referenced method 'void invalidate()' in program class com.sun.activation.viewers.ImageViewer Warning:com.sun.activation.viewers.ImageViewer: can't find referenced method 'void validate()' in program class com.sun.activation.viewers.ImageViewer Warning:com.sun.activation.viewers.ImageViewer: can't find referenced method 'void doLayout()' in program class com.sun.activation.viewers.ImageViewer Warning:com.sun.activation.viewers.ImageViewerCanvas: can't find referenced method 'void invalidate()' in program class com.sun.activation.viewers.ImageViewerCanvas Warning:com.sun.activation.viewers.ImageViewerCanvas: can't find referenced method 'void repaint()' in program class com.sun.activation.viewers.ImageViewerCanvas Warning:com.sun.activation.viewers.TextEditor: can't find referenced method 'void setLayout(java.awt.LayoutManager)' in program class com.sun.activation.viewers.TextEditor Warning:com.sun.activation.viewers.TextEditor: can't find referenced method 'void invalidate()' in program class com.sun.activation.viewers.TextEditor Warning:com.sun.activation.viewers.TextViewer: can't find referenced method 'void setLayout(java.awt.LayoutManager)' in program class com.sun.activation.viewers.TextViewer Warning:com.sun.activation.viewers.TextViewer: can't find referenced method 'java.awt.Component add(java.awt.Component)' in program class com.sun.activation.viewers.TextViewer Warning:com.sun.activation.viewers.TextViewer: can't find referenced method 'void invalidate()' in program class com.sun.activation.viewers.TextViewer Warning:javax.activation.ActivationDataFlavor: can't find referenced method 'boolean isMimeTypeEqual(java.awt.datatransfer.DataFlavor)' in program class javax.activation.ActivationDataFlavor Warning:there were 14 unresolved references to program class members. Your input classes appear to be inconsistent. You may need to recompile the code. (http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedprogramclassmember) :vet:proguardInternalRelease FAILED Error:Execution failed for task ':vet:proguardInternalRelease'. > java.io.IOException: Please correct the above warnings first. 

Answer 1

It is disgusting to clean. Better libraries now include their settings in the library package, but older (or more lazy) ones are still not. Following is the following process:

In development:

• Whenever a new library is included, be sure to check its documentation for the ProGuard settings it offers. (If you are diligent with this, it will save a lot of confusion and dig up later.)
• If the author of the library offers an AAR package (for example, adding '@aar' to the end of the gradle dependency line to get the full AAR instead of a simpler JAR), they could even include the necessary ProGuard exceptions in there for you, which will automatically get picked up. (But, in my experience, most authors still do not take this extra step.)
• Whenever a new namespace / class is added to custom code that requires dynamic introspection, for example, when using dependency injection containers or JSON parsers, make sure ProGuard is configured to select them depending on their package name or add their own class for time.

After creating and receiving errors:

• Start with all lines starting with the prefix error: then warning: (lines note: will not stop the build).
• Check the namespace that appears on each line. Find a linked library (e.g. com.newrelic.SomeClass , probably for the New Relic library). If you can't find it, try a Google search to see if the namespace can help you track down github README or something else that can determine which library this namespace is in. Or browse the list of Android Studio> Project> Packages> Libraries (it takes some time to display for the first time) and track the namespace there. We hope that the source code will be available and will contain information about the library in the comments of the file header.
• See the documentation for this library. Hopefully he mentioned the necessary changes to ProGuard.
• Rebuild.

All changes made to the docs library are found, but still receive warnings:

• Start adding -dontwarn lines. For example: -dontwarn com.newrelic.** (Do not forget the double asterisk to ignore the entire tree under this namespace, otherwise one star will ignore only direct child namespaces.)
• If you start using the dontwarn instructions , you must test your compiled application (APK)! . Because now it is very likely that it will crash for you, although debugging (non-ProGuard) works fine. Be sure to check all the libraries that you used, check the logcat messages and make sure that you execute all the code paths / classes that you blindly skip with dontwarn !

Screw it, my boss said I should let this thing go already:

• Disable ProGuard: - (

Either use the project properties dialog in Android Studio, or edit the build.gradle file and change android { buildTypes { release { minifyEnabled true } } } and set it to false .

You won’t get ProGuard optimization, the APK will be much larger and the code will not be confused. But if your boss just needs it now, and you don’t have time to debug, this is not the end of the world to turn it off.

Although you really should use ProGuard. Maybe it's time to talk with the boss about giving developers more time to do the boring technical things we need.