java - What is the use of recursive type bound in this case -


i have following piece of code

public static <t extends comparable<t>> t max(list<t> list){     iterator<t> iter = list.iterator();     ...     // code finding max element in list     ...  }

my question is, need recursive type bound in case? far understanding, t extends comparable < t > means that, t can compared t itself. comes fact that, class 't' implements comparable<t> , so, 

class myclass implements comparable<myclass>{ }

if wrong here, feel free correct me.

so coming actual doubt, why need specify < t extends comparable < t > > ? ways argument list<t> list going contain elements of same type. i.e., suppose pass parameter of type list < myclass2 > , elements going of same type, i.e. myclass2..

so implication of recursive type bound? in advance.

why need specify <t extends comparable<t>>? because comparable not require implementing class comparable itself. in theory write like

class circle extends shape implements comparable<integer> {     ... }

since comparable not make restriction, have on end when writing function. however, given bound more restrictive need be. make call 

public static <t extends comparable<? super t>> t max(list<t> list) {     ... }

that mean t comparable superclass of itself. reason want given in fruit example of rgettman. t still comparable itself, comparable not have defined respect t itself.


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