Sonar "Make transient or serializable" error

Question

I have the following serializable class (implements serializable):

public class Test implements Serializable{

private String id;

private Map<String,Object> otherProperties;

}

However , it seems like this property is causing some problems with serialization :

How can I solve this problem ?

Also , is there any downside in not making this transient or serializable ? Will I be able to serialize this class fully ?

Scrutable

rules.sonarsource.com/java/RSPEC-1948 – Semitropical

Answer 1

The Map interface does not extend the Serializable interface, which is why Sonar is warning you.

When serializing an instance of Test, you must choose whether or not you want otherProperties to be serialized.

If you don't want to serialize otherProperties, then the field should be marked as transient:

private transient Map<String, Object> otherProperties;

Otherwise, you can change the type of otherProperties to an implementation of Map that implements Serializable, such as HashMap.

Trousseau

If we change the otherProperties to the type HashMap or anyother implementation of Map interface, sonar will raise another issue to force us to use the Interface type in variables. – Syndesmosis

if we do this then in Criteria Mata model that filed will be deleted . – Insomnia

Added HashMap but this still does not work for me since Sonar does not know if Object is serializable. – Lockhart

Answer 2

Add this 2 methods to your class:

 private void writeObject(java.io.ObjectOutputStream stream)
        throws IOException {
    stream.defaultWriteObject();
}

private void readObject(java.io.ObjectInputStream stream)
        throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
}

Ombudsman

This, and plus annotation on those methods: @Serial – Scapegrace

Answer 3

Change Object to Serializable and then Sonar should be happy.

private Map<String, Serializable> otherProperties;

Since your class is Serializable its fields also should be Serializable.

Faxon

If you're injecting a list of types implementing an interface you can't just replace your types by Serializable though – Femmine

Answer 4

If it's an option (for instance, if you are using Jackson to (de)serialize your class), remove the Serializable marker from your Test class. The serialization will still work and you will get rid of the warning in Sonar.

Declamation

Answer 5

I was having a similar issue but in contrast to Nexussim Lements I've been using an interface that gets serialized but still SonarLint showed me a warning:

public class BasicCheck implements Serializable { ... }

public class Case implements Serializable {
   private BasicCheck basicCheck; // Sonarlint throws warning here
   ...
}

Luckily I've found FAlfeao's solution to be working. All I had to do was to add these two methods to my Case-class:

private void writeObject(java.io.ObjectOutputStream stream)
        throws IOException {
    stream.defaultWriteObject();
}

private void readObject(java.io.ObjectInputStream stream)
        throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
}

Thoroughwort

Answer 6

Map value type should be specified to extends Serialzable:

public class Test<T extends Serializable> implements Serializable{

private String id;

private Map<String,T> otherProperties;

}

Deafanddumb