How to protect from Nulls...
Each public method in each class rejects any null values with an IllegalArgumentException.
This is enforced by test cases - each test case extends from a common TestCase that checks public methods by ensuring they throw exception when null is passed in.
- No objects exist with nulls as values.
- All classes have default values (objects) that can be persisted to the Database. Have default values like "". Or optional values (like something not yet done) are separate relations.
http://www.javalobby.org/java/forums/t17491.html
class Xxx {
public static EMPTY_XXX = new Xxx();
...
private Object readResolve() {
return EMPTY_XXX;
}
}
You should write code that checks that == works - as a suite of tests too. Like AssertSerialization.
Null-safe operators in Java 7:
