final - What steps can you make to make a java object with a setter to be immutable? -

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• how final keyword works 17 answers

what can make object such immutable? concerned solving public void somemethod(someobject someobject) { } <== case

for example:

public class someobject {    private string somestring;     public void setsomestring(string somestring) {       this.somestring = somestring;    }    public void getsomestring() {       return somestring;    } }   public void somemethod() {    final someobject someobject = new someobject();    someobject.set("want prevent this"); // <-- someobject mutable in case }  public void somemethod(someobject someobject) {    someobject.set("and prevent this!"); // <-- , } 

you right, declaring object final not make immutable. preventing final variable being re-assigned new object, object assigned mutated if mutating methods available.

you can give object interface immutable, , program interface:

interface immutablecar {     string getmake();     string getmodel(); } class car implements immutablecar {     public car(string make, string model) {         this.make = make;         this.model = model;     }     private string make;     private string model;     public string getmake() { return make; }     public void setmake(string m) { make = m; }     public string getmodel() { return model; }     public void setmodel(string m) { model = m; } } 

if this

immutablecar car = new car("vw", "bora"); 

you not able access mutating methods without explicit cast. of course not make object immutable, because casting remain possibility, 1 argue other immutable objects can changed going through reflection, approach lets expose immutable behavior.