Java Basic (6) - Objects containing objects, Passing an object to a method

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Objects containing objects

• Object can contain any type including the object type (itself)

Person object contains a type of itself 

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Passing an object to a method

• Java always passes a copy of the variable to a method, not the variable itself
• When passing a primitive type, a copy of the value is passed to the method
• When passing an object, a copy of the reference is passed to the method

 

x is just a copy of the value that was passed to the method

x in main is still 5

 

Let's apply this to objects

 

Modifying where it point to does not affect the initial reference that was passed to the method. However,

p here is still accessing the same object in memory, so calling an instance method will affect the object.

haveBirthday method

 

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