When using an android bundle, why does a serialised stack deserialise as an ArrayList?

Question

Serialisation:

Bundle activityArguments = new Bundle();
Stack<Class<? extends WizardStep>> wizardSteps = new Stack<Class<? extends WizardStep>>();
wizardSteps.push(CreateAlarmStep5View.class);
wizardSteps.push(CreateAlarmStep4View.class);
wizardSteps.push(CreateAlarmStep3View.class);
wizardSteps.push(CreateAlarmStep2View.class);
wizardSteps.push(CreateAlarmStep1View.class);
        
activityArguments.putSerializable("WizardSteps", wizardSteps);

Deserialisation:

Stack<Class<? extends WizardStep>> wizardSteps = 
(Stack<Class<? extends WizardStep>>) getIntent().getExtras().getSerializable("WizardSteps");

Exception:

12-20 23:19:45.698: E/AndroidRuntime(12145): Caused by: java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.util.Stack

Answer 1

Its known bug. I surprise that it still exists.

Use generic container like:

public class SerializableHolder implements Serializable {
private Serializable content;
public Serializable get() {
    return content;
}
public SerializableHolder(Serializable content) {
    this.content = content;
 }
}

If you use GSON library, convert your Stack to String and use as single String for Bundle without Serialize. It should work.

Answer 2

Just cast the serializable you retrieved from the bundle to a List, create a new Stack, and then add all the List items to the stack:

Serializable serializable = savedInstanceState.getSerializable("key");
List<Something> list = (List<Something>) serializable;
Stack<Something> stack = new Stack<Something>();
stack.addAll(list);

Why cast to List and not ArrayList you ask? Because if this is fixed in some Android version, you won't have a ClassCastException again.