app crashes when proguard is enabled

Question

Getting this when proguard is enabled, if I set minify enabled false, it runs perfectly, don't know what I missed, please help. I think I have missed something to add in proguard, but I don't understand then studio built an apk successfully?

java.lang.NullPointerException at co.crowdie.a.b.a(Unknown Source)
    at co.crowdie.a.b.a(Unknown Source)
    at android.support.v7.widget.RecyclerView$a.a(Unknown Source)
    at android.support.v7.widget.RecyclerView$a.b(Unknown Source)
    at android.support.v7.widget.RecyclerView$n.a(Unknown Source)
    at android.support.v7.widget.RecyclerView$n.c(Unknown Source)
    at android.support.v7.widget.LinearLayoutManager$c.a(Unknown Source)
    at android.support.v7.widget.LinearLayoutManager.a(Unknown Source)
    at android.support.v7.widget.LinearLayoutManager.a(Unknown Source)
    at android.support.v7.widget.LinearLayoutManager.c(Unknown Source)
    at android.support.v7.widget.RecyclerView.J(Unknown Source)
    at android.support.v7.widget.RecyclerView.k(Unknown Source)
    at android.support.v7.widget.RecyclerView.onLayout(Unknown Source)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.support.design.widget.m.b(Unknown Source)
    at android.support.design.widget.aa.a(Unknown Source)
    at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.a(Unknown
    Source)                                                        at
    android.support.design.widget.CoordinatorLayout.onLayout(Unknown Source)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1160)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:515)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:450)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1888)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1742)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1651)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:515)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:450)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1888)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1742)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1651)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:515)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:450)
    at android.view.View.layout(View.java:15125)
    at android.view.ViewGroup.layout(ViewGroup.java:4862)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2317)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2023)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1189)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6223)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:788)
    at android.view.Choreographer.doCallbacks(Choreographer.java:591)
    at android.view.Choreographer.doFrame(Choreographer.java:560)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java
    :774)                                                        at
    android.os.Handler.handleCallback(Handler.java:808)
    at android.os.Handler.dispatchMessage(Handler.java:103)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:5292)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:
    828)
    at
    com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
    at dalvik.system.NativeStart.main(Native Method)

Answer 1

add these lines to your proguard rules file and try again:

-dontwarn android.support.design.**
-keep class android.support.design.** { *; }
-keep interface android.support.design.** { *; }
-keep public class android.support.design.R$* { *; }

-keep public class android.support.v7.widget.** { *; }
-keep public class android.support.v7.internal.widget.** { *; }
-keep public class android.support.v7.internal.view.menu.** { *; }

-keep public class * extends android.support.v4.view.ActionProvider {
public <init>(android.content.Context);
}

also these are the defualt things that you better have in your proguard rules:

-keep public class * extends android.app.Activity
-keep public class * extends android.app.Application
-keep public class * extends android.app.Service
-keep public class * extends android.content.BroadcastReceiver
-keep public class * extends android.content.ContentProvider

-keep public class * extends android.view.View {
public <init>(android.content.Context);
public <init>(android.content.Context, android.util.AttributeSet);
public <init>(android.content.Context, android.util.AttributeSet, int);
public void set*(...);
}

-keepclasseswithmembers class * {
public <init>(android.content.Context, android.util.AttributeSet);
}

-keepclasseswithmembers class * {
public <init>(android.content.Context, android.util.AttributeSet, int);
}

-keepclassmembers class * extends android.content.Context {
public void *(android.view.View);
public void *(android.view.MenuItem);
}

-keepclassmembers class * implements android.os.Parcelable {
static ** CREATOR;
}

-keepclassmembers class **.R$* {
public static <fields>;
}

-keepclassmembers class * {
@android.webkit.JavascriptInterface <methods>;
}

-dontwarn android.support.**