equals and hashCode

Whenever we override the equals() method in any class, we must also override the hashCode() method.

if(o1.equals(o2))

then

o1.hashCode() == o2.hashCode()
must also be true.

For more details - http://www.ibm.com/developerworks/java/library/j-jtp05273.html

Creating Booleans

FindBugs suggests that we should not instntiate Boolean objects like this

Boolean b = new Boolean(false);

instead we must use the creational method

Boolean b = Boolean.valueOf(false);

This is better for performance, since the Boolean object caches 2 immutable Booelan objects for true and false values.