Confusion over UnderInitialization

[Jon Schewe]

I'm having some issues understanding the errors about initialization. I've read over the section in the manual a couple of times and I thought I had it figured out, but the compiler doesn't agree with me.

I have the following class:

public class DefaultBean implements Bean, Serializable {

  /**

   * Base constructor. Source is {@code this}.

   */

  public DefaultBean() {

    this.propertyListener = new PropertyChangeSupport(this);

}

  private final PropertyChangeSupport propertyListener;

}

I understand that "this" is under initialization when it's passed to the constructor for PropertyChangeSupport. I believe that the appropriate annotation is @UnderInitialization(Object.class).

    @SafeEffect

    public PropertyChangeSupport(@UnderInitialization(Object.class) @PolyUI Object sourceBean) {

...

}

However I'm still getting errors. In addition to the specified class, I'm not clear on when to use ".class" and when not to in these annotations.

/home/jpschewe/projects/infra/working-dir/src/main/java/net/mtu/eggplant/util/DefaultBean.java:42: warning: [assignment.type.incompatible] incompatible types in assignment.

    this.propertyListener = new PropertyChangeSupport(this);

                            ^

  found   : @UnderInitialization(java.beans.PropertyChangeSupport.class) @NonNull PropertyChangeSupport

  required: @Initialized @NonNull PropertyChangeSupport

/home/jpschewe/projects/infra/working-dir/src/main/java/net/mtu/eggplant/util/DefaultBean.java:42: warning: [argument.type.incompatible] incompatible argument for parameter sourceBean of <init>.

    this.propertyListener = new PropertyChangeSupport(this);

                                                      ^

  found   : @UnderInitialization @NonNull DefaultBean

  required: @Initialized @NonNull Object

Thanks,

Jon

[Michael Ernst]

Jon-

Please see section 3.8.6, "Initialization of circular data structures", in the Checker Framework manual.

If you write "@NotOnlyInitialized" on the propertyListener field, then the Nullness Checker will approve your code.

Below is a complete example.

Mike

import org.checkerframework.checker.initialization.qual.NotOnlyInitialized;
import org.checkerframework.checker.initialization.qual.UnknownInitialization;

class DefaultBean {
  @NotOnlyInitialized private final PropertyChangeSupport propertyListener;

  public DefaultBean() {
    this.propertyListener = new PropertyChangeSupport(this);
  }
}

class PropertyChangeSupport {
  public PropertyChangeSupport(@UnknownInitialization(Object.class) Object sourceBean) {}
}

[Jon Schewe]

Mike,

Thanks for the pointer. However it doesn't appear to be working for me. I needed to add @NotOnlyInitialized to PropertyChangeListener.source as well.

public class DefaultBean implements Bean, Serializable {

  /**

   * Base constructor. Source is {@code this}.

   */

  public DefaultBean() {

    this.propertyListener = new PropertyChangeSupport(this);

  }

  private final @NotOnlyInitialized PropertyChangeSupport propertyListener;

}

@PolyUIType

public @UsesObjectEquals class PropertyChangeSupport implements Serializable {

 @SafeEffect

    public PropertyChangeSupport(@PolyUI @UnknownInitialization(Object.class) Object sourceBean) {

        if (sourceBean == null) {

            throw new NullPointerException();

        }

        source = sourceBean;

    }

    private @NotOnlyInitialized Object source;

}

Without @NotOnlyInitialized on PropertyChangeSupport.source I get the error below.

/home/jpschewe/projects/infra/working-dir/src/main/java/net/mtu/eggplant/util/DefaultBean.java:45: warning: [argument.type.incompatible] incompatible argument for parameter sourceBean of <init>.

    this.propertyListener = new PropertyChangeSupport(this);

                                                      ^

  found   : @UnderInitialization(java.lang.Object.class) @NonNull DefaultBean

  required: @Initialized @NonNull Object