google app engine - I need help parsing this statement from the GAE/Java documentation on data classes -


This section is killing me, I appreciate if someone can help me understand it.

If the area is not a faucet worth the value type, then without exception, it throws an exception by loading an entity. This will not happen if this unit was created from the same JDO class. , Which was used to reuse this example, but if the JDO class may change, then

  1. What is a worthless value type?
  2. How can you load an entity without this property?
  3. What does this mean: "This will not happen if this unit was created from the same JDO class, for example?"
  4. When you say "but JDO class changes So maybe ", how can a JDO class change?

    1. An object type is taped primitives (such as Intel or Boolean) blank Can not be
    2. An older version of the class could not be an asset and therefore, data will not have the property in the datastore, and when you try to match it with the new category, then it will have to clear the property.
    3. Because (2) can only happen when class has changed.
    4. When you update your code and apply a new version.

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