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android – Proguard issue while using GSON

Posted by: admin June 15, 2020 Leave a comment


I am using Gson in my application and for that, i am using some classes with name as same as the one in using Json. My application works well, But while writing proguard, application crashes, I guess some of the classes are shrinking.
my error is :

java.lang.ClassCastException: com.google.gson.internal.StringMap cannot be cast to com.sample.package.GsonClass

How to&Answers:

You need to add these lines to your proguard so that gson class is kept while signing your app..

##---------------Begin: proguard configuration for Gson  ----------
# Gson uses generic type information stored in a class file when working with fields. Proguard
# removes such information by default, so configure it to keep all of it.
-keepattributes Signature

# Gson specific classes
-keep class sun.misc.Unsafe { *; }
#-keep class com.google.gson.stream.** { *; }

# Application classes that will be serialized/deserialized over Gson
-keep class com.google.gson.examples.android.model.** { *; }

##---------------End: proguard configuration for Gson  ----------


Another reason is: before use

List<T> list = gson.fromJson(jsonString, type);

you should construct the correct typeToken, like this:

Type type = new TypeToken<List<T>>(){}.getType();
List<T> list = gson.fromJson(jsonString,type)