Since equal objects must have equal hash codes, overriding equals requires overriding hashCode for the methods to remain consistent and in compliance. Example: if your goal is to provide update the ...

If only override hashCode, then after reaching the same hash bucket (when do contains (obj)), java will not know they are equal or not as equals is not redefined. I guess that the default equals ...

If you are fortunate enough to be using JDK 7, the newly available Objects class is the obvious (at least to me) choice for implementing the “common” Java object methods such as equals (Object ...