java - Sorting through ArrayList of Objects, Add given Instance to ArrayList of given instances issue -

i'm getting error

no suitable method found add(object), method collected.add(student not applicable)

when try following code. swear i've done way before? confused. appreciate insights. cheers

    //sort , display list of student objects sortby (surname or id) public static void sortanddisplaystudents(string sortby, arraylist<object> objlist) {     arraylist<student> students = new arraylist<>();      //add objcets in objlist student     for(object s: objlist) {         if(s instanceof student) {             students.add(s);         }     } } 

just avoid errors, change way construct array list:

arraylist<student> students = new arraylist<>();  arraylist<student> students = new arraylist<student>(); 

as add method, want cast passing object otherwise jvm not know object being passed instanceof student:

students.add((student) s); 

also, should ide, solve these problems before happen.

wiki