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ProGuard for Android and Retrofit2 Converter Gson?

Posted by: admin May 14, 2020 Leave a comment

Questions:

i am using ProGuard in my project but its giving wrong data in new Gson().toJson(Request);

i am getting out put

{"a":"manage","b":"689184d4418b6d975d9a8e53105d3382","c":"10","d":"76"}

instead of

{"username":"manage","password":"689184d4418b6d975d9a8e53105d3382","value":"10","store":"76"}

My ProGuard rule

-dontwarn okio.**
-dontwarn retrofit2.Platform$Java8
-dontwarn sun.misc.Unsafe
-dontwarn org.w3c.dom.bootstrap.DOMImplementationRegistry
-dontwarn retrofit2.**
-keep class retrofit2.** { *; }
-keepattributes Signature
-keepattributes Exceptions
-keepclassmembers class rx.internal.util.unsafe.** {
    long producerIndex;
    long consumerIndex;
}

-keepclasseswithmembers class * {
    @retrofit2.http.* <methods>;
}
-keep class com.google.gson.** { *; }
-keep class com.google.inject.** { *; }

and i am using

 compile 'com.squareup.retrofit2:converter-gson:2.0.0'

is there a new recommended ProGuard configuration for retrofit2:converter-gson in Android?

How to&Answers:

you either want to keep the class you are using with gson or use @SerializedName annotation.

option 1 (keep class)

// all classes in a package
-keep class com.example.app.json.** { *; }
// or a specific class
-keep class com.example.app.json.SpecificClass { *; }

option 2 (use @SerializedName):

public class YourJsonClass{
   @SerializedName("name") String username;

   public MyClass(String username) {
     this.username = username;
   }
 }

with the second option proguard still obfuscates the class and field names but gosn can use the annotation to get the correct name for each field

Answer:

Annotate your JSON model classes with @Keep.

Answer:

Use android @Keep annotation on you desired class like authToken

@Keep
data class AuthToken(
    var access_token: String,
    var token_type: String,
    var expires_in: String,
    var userName: String,
    var issued: String,
    var expires: String) {}

And then in ProGuard add below line:
If using androidx

-keep @androidx.annotation.Keep public class *

Else

 -keep @android.support.annotation.Keep public class *

Answer:

In my case, I was using Moshi for JSON with Retrofit, but the problem was the same. It worked in debug, but after building with ProGuard, the RecyclerView that used the model crashed with a NullPointerException, because the list was full of empty model objects, since Moshi didn’t recognize any of the fields. I think the exact same thing happens with Gson.

One solution is to annotate every field with its corresponding serialized name:

@Json(name="username") String username;

That way ProGuard can obfuscate the variable names without breaking the conversion.

The other solution is adding a “keep” option like Dodge suggested, in the proguard-rules.pro file

-keep public class com.example.model.User