Realm-java: Problem with Jackson and RxJava

[leisim]

Goal

Use Realm and Jackson without RxJava dependency.

Actual Results

The Realm docs suggest to add empty Observable and Flowable classes but Realm checks the existence of io.reactivex.Flowable to determine if rx is available and crashes.
Here is the relevant line.

java.lang.NoClassDefFoundError: Failed resolution of: Lio/reactivex/BackpressureStrategy;
at io.realm.rx.RealmObservableFactory.<clinit>(RealmObservableFactory.java:79)
at io.realm.RealmConfiguration$Builder.build(RealmConfiguration.java:806)
at io.realm.Realm.init(Realm.java:247)
...

Version of Realm and tooling

Realm version(s): 4.1.0

[Zhuinden]

I guess you also need to add the dummy class for io.reactivex.BackpressureStrategy

[leisim]

This does not solve the problem since Realm assumes Rx is present. I get the following exception:

java.lang.NoSuchFieldError: No static field LATEST of type Lio/reactivex/BackpressureStrategy; in class Lio/reactivex/BackpressureStrategy; or its superclasses (declaration of 'io.reactivex.BackpressureStrategy' appears in /data/app/de.mycompany.myapp-2/base.apk:classes3.dex)
at io.realm.rx.RealmObservableFactory.<clinit>(RealmObservableFactory.java:79)
at io.realm.RealmConfiguration$Builder.build(RealmConfiguration.java:806)
at io.realm.Realm.init(Realm.java:247)

[Zhuinden]

Well, we are getting there :smile:

I guess the solution will be

package io.reactivex;

class Observable {
}

and

package io.reactivex;

class Flowable {
}

and

package io.reactivex;

enum BackpressureStrategy {
    LATEST;
}

And then it should work.

[nhachicha]

we should update the doc to reflect these changes

[mimoccc]

Does not work :
java.lang.IllegalAccessError: Illegal class access: 'io.realm.rx.RealmObservableFactory' attempting to access 'io.reactivex.BackpressureStrategy' (declaration of 'io.realm.rx.RealmObservableFactory' appears in /data/app/eu.mjdev.mediaplayer.debug-1/base.apk)
at io.realm.rx.RealmObservableFactory.(RealmObservableFactory.java:79)
at io.realm.RealmConfiguration$Builder.build(RealmConfiguration.java:805)
at io.realm.Realm.init(Realm.java:248)
at eu.mjdev.mediaplayer.application.Application.onCreate(Application.java:16)
at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1012)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4586)
at android.app.ActivityThread.access$1600(ActivityThread.java:154)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1378)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5296)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:707)

[mimoccc]

Why realm want programmers use RX??? Only cause of observable? They can not write their class?

[mimoccc]

In most of my apps I use realm only to store json serialized object, as other way does not work.
No HashMap support...
No real ArrayList support...
No simple inner object support...
Only single objects with int, double, string & etc, You call it database?
It is really fast but...
May be this should be better to escape before Rx re-implementation...

[Zhuinden]

Read https://stackoverflow.com/a/47062181/2413303

[Armenm]

Doesn't work
java.lang.IllegalAccessError: Illegal class access: 'io.realm.rx.RealmObservableFactory' attempting to access 'io.reactivex.BackpressureStrategy' (declaration of 'io.realm.rx.RealmObservableFactory' appears in /data/app/io.sendtask-1/base.apk:classes2.dex) at io.realm.rx.RealmObservableFactory.<clinit>(RealmObservableFactory.java:79) at io.realm.RealmConfiguration$Builder.build(RealmConfiguration.java:805) at io.realm.Realm.init(Realm.java:248) at io.sendtask.application.MainApplication.onCreate(MainApplication.java:41) at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1014) at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4869) at android.app.ActivityThread.access$1800(ActivityThread.java:154) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1457) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5582) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

[Zhuinden]

@armenm did you try the second half of the answer I provided in https://stackoverflow.com/a/47062181/2413303

[Armenm]

Yes, I have created 3 classes in io.reactivex package. jackson-databind section in Realm docs
I use classpath "io.realm:realm-gradle-plugin:4.2.0".
I have also added this to multidex-config.txt
io/reactivex/BackpressureStrategy.class
io/reactivex/Flowable.class
io/reactivex/Observable.class

[Zhuinden]

@armenm

I have never seen that before but i guess you could bring over the whole enum

public enum BackpressureStrategy {
    MISSING,
    ERROR,
    BUFFER,
    DROP,
    LATEST
}