java - How do I ask for a parameter to be a mutable Map? -

i have function accepts map of parameters, adds them before using them:

public string dorequest(string endpoint, map<string, string> parameters) {     parameters.put("limit", "50");     ... } 

it's convenient create map using guava's immutablemap.of():

dorequest("/comments", immutablemap.of("filter", "true")); 

however, throws java.lang.unsupportedoperationexception @ runtime.

two questions:

1) can declare dorequest in way example hashmap , treemap fine using immutablemap compile time error?

2) inside dorequest, how detect it's immutablemap, run params = maps.newhashmap(params)?

1) can declare dorequest in way example hashmap , treemap fine using immutablemap compile time error?

no. immutablemap implements map, can't compile time error. problem map.put, allows throw. it'd better have map without put , mutablemap interface... there's nothing in java software around relies on it.

2) inside dorequest, how detect it's immutablemap, run params = maps.newhashmap(params)?

you'd better there's collections.unmodifiablemap , implement map refusing put.

if you're concerned performance, you'll need instanceof check.