java - Copying object fields -

what best way of copying classes when need have 2 independent variables? have simple class:

public class myclass  { boolean = false; string b= "not empty"; } 

do need make method :

assign(myclass data ) { a= data.a; b= data.b; } 

is there automatic method copy (duplicate) objects in java?

do need make method :

pretty close. instead of making method, should make constructor. such constructors called copy constructor, , create them this:

myclass(myclass data) {       = data.a;     b = data.b; } 

and create copy of instance, use constructor this:

myclass obj1 = new myclass(); myclass obj2 = new myclass(obj1); 

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copy constructor can tedious:

using copy constructor create deep-copy can tedious, when class has mutable fields. in case, assignment create copy of reference, , not object itself. have create copy of fields (if want deep copy). can go recursive.

a better way create deep copy serialize , deserialize object.

why not use clone()?

addition of clone() method in object class big mistake, imo. should avoid using cloning objects.

• for one, use method, have implement cloneable interface, surprise doesn't have clone() method. in fact, it's marker interface.
• return type of object#clone() method object. so, means can return instance of unrelated class, leading code potential classcastexception @ runtime.

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see also:

• how make deep copy of object in java?
• what difference between deep copy , shallow copy?
• josh bloch on design - copy constructor versus cloning