Android：NoClassDefoundError仅在发布版本上

Question

我正在Android Studio上尝试在发布模式下构建我的项目。
在调试模式下一切正常，但是在发布模式下会出现以下错误...

08-26 17:59:05.599  31696-31931/? W/System.err﹕ java.lang.NoClassDefFoundError: a.a.b.l
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at java.lang.Class.classForName(Native Method)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at java.lang.Class.forName(Class.java:308)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at java.lang.Class.forName(Class.java:272)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at com.a.a.a.a(Unknown Source)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at com.a.a.a.a(Unknown Source)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at com.a.a.e.b(Unknown Source)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at com.a.a.e.a(Unknown Source)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at com.a.e.a.uncaughtException(Unknown Source)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:693)
08-26 17:59:05.599  31696-31931/? W/System.err﹕ at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:690)
08-26 17:59:05.600  31696-31931/? E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #2
    Process: com.soonoo.mobilecampus, PID: 31696
    java.lang.RuntimeException: An error occured while executing doInBackground()
            at android.os.AsyncTask$3.done(AsyncTask.java:300)
            at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
            at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
            at java.util.concurrent.FutureTask.run(FutureTask.java:242)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:818)
     Caused by: java.lang.ExceptionInInitializerError
            at a.a.b.l.a(Unknown Source)
            at a.a.b.m.<clinit>(Unknown Source)
            at a.a.b.f.<init>(Unknown Source)
            at a.a.b.e.<init>(Unknown Source)
            at a.a.c.di.b(Unknown Source)
            at a.a.c.di.a(Unknown Source)
            at a.a.c.b.a(Unknown Source)
            at a.a.c.ae.b(Unknown Source)
            at a.a.a.a(Unknown Source)
            at com.soonoo.mobilecampus.mainlist.h.a(Unknown Source)
            at com.soonoo.mobilecampus.mainlist.h.doInBackground(Unknown Source)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:818)
     Caused by: java.lang.NullPointerException: in == null
            at java.util.Properties.load(Properties.java:246)
            at a.a.b.l.d(Unknown Source)
            at a.a.b.l.<clinit>(Unknown Source)
            at a.a.b.l.a(Unknown Source)
            at a.a.b.m.<clinit>(Unknown Source)
            at a.a.b.f.<init>(Unknown Source)
            at a.a.b.e.<init>(Unknown Source)
            at a.a.c.di.b(Unknown Source)
            at a.a.c.di.a(Unknown Source)
            at a.a.c.b.a(Unknown Source)
            at a.a.c.ae.b(Unknown Source)
            at a.a.a.a(Unknown Source)
            at com.soonoo.mobilecampus.mainlist.h.a(Unknown Source)
            at com.soonoo.mobilecampus.mainlist.h.doInBackground(Unknown Source)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:818)

问题是异常消息不显示发生错误的类和方法的名称。
我在项目中使用的所有第三方库都是在build.gradle中指定的。
如何解决此问题？

Answer 1

问题基本上是这样的：

buildTypes {
        release {
            **minifyEnabled false**
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

如果您将minifyEnabled设置为false，它应该可以解决您的问题。如果您想使用minify特性，那么您可以将progaurd规则添加到您的build.gradle中。例如，对于Butterknife库，您必须添加以下内容：

-keep class butterknife.** { *; }
-dontwarn butterknife.internal.**
-keep class **$$ViewBinder { *; }

-keepclasseswithmembernames class * {
    @butterknife.* <fields>;
}

-keepclasseswithmembernames class * {
    @butterknife.* <methods>;
}

很高兴我能帮上忙