java - How to pass Object object in functional interface/lambda call -


so, have piece of code goes like

public static void printstuff(object[] stuffs, function<?, string> func) {     for(object stuff : stuffs) {         string stringstuff = func.apply(stuff);         system.out.println(stringstuff);         // or whatever, done string not relevant     }     // ...

this method called arrays of different types, , corresponding func value, example:

printstuff(arrayofclasses, (class<?> c) -> c.getsimplename()); printstuff(arrayofstrings, (string s) -> '"' + s + '"'); printstuff(arrayofobjects, o -> o.tostring());

so need stuffs object[], because first common superclass of different types amongst method's calls.

and on compilation, get:

myclass.java:6: error: incompatible types: object cannot converted cap#1         string stringstuff = func.apply(stuff);                                         ^   cap#1 fresh type-variable:     cap#1 extends object capture of ?

my guess javac rants parameter give function<?, string> call, type, object, not extend object.

so question is, how can pass object parameter function<?, string>?

i can change interface types <object, string>, breaks others calls (with class[], string[], etc) , imply losing pretty whole point of genericity, wouldn't it?

unless there way change stuffs type <? extends object>[], or generic type, , i'm pretty sure it's not possible.

thanks in advance, folks.

edit:

if change method generic one, i.e.:

public static <u> void printstuff(object[] stuffs, function<u, string> func) {

i still compilation error :

myclass.java:6: error: method apply in interface function<t,r> cannot applied given types;             string stringstuff = func.apply(stuff);                                      ^   required: u   found: object   reason: argument mismatch; object cannot converted u

one solution use:

public static <t> void printstuff(t[] stuffs, function<t, string> func) {     for(t stuff : stuffs) {         // ....

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