This is complete Tutorial of Observer Design Pattern . Feel Free to add something useful to it .
As the name suggests you can see Observer Design Pattern as something in which an observer observes some observable entity and changes its state according to that . So we can say that Observer design pattern is useful when you are interested in the state of an object and want to get notified whenever there is any change. In observer pattern, the object that watch on the state of another object are called Observer and the object that is being watched is called Subject.
To give you more insight of this pattern let’s consider an example .
Suppose we have a weather station which is responsible for giving the complete information about temperature change , humidity etc. and we have some services which makes use of the information given by weather station . So now we can clearly see that weather station is something that is being observed and services are observers as services are the one that change their state as the information in weather station is updated .
To know more plaese follow this link -: https://medium.com/@ngneha090/observer-design-pattern-weather-station-design-c54f5d23bae9
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