bonjour je ne sais pk la methode tostring ne marche pas

public class personne{


			private String nom;
			private String prenom;
			private int age;
			public personne(){
				this.nom="ahmed";
				this.prenom="sami";
				this.age=20;
				
			}
			public personne(String nom,String prenom,int age){
				this.nom=nom;
				this.prenom=prenom;
				this.age=age;
			}
			
			public String getName(String  nom){
		return nom;	
			}
			public String getPrenom(String  nom){
				return prenom;	
		}
			public int getAge(int age){
				return age;
			}
			 public void setPrenom(String P){ 
				    this.prenom=P; 
				  } 
				  public void setNom(String N){ 
				    this.nom=N; 
				  } 
				  public void setAge(int age){ 
				    this.age=age; 
				  }
public String toString(String nom,String prenom,int age){
	return ("+nom+","+nom+","+age+");
}
public static void main(String[]args){
	personne p=new personne("ahmed","sami",15);
	System.out.println(p.toString());
}
	}