ObjectInputStream dove sbaglio?

[superPoseidon]

mi potete dire perche non melo stampa sulla console gli oggetti che li carico da file primo_file.dat, alla fine del programma mi stampa : error nel spertura di file
// classe people
package person;

imprt java.io.Serializable;
public class people implements Serializable{
protected String name;
protected String surname;
protected int age;
protected String address;

public people(String nome, String cognome, int eta){
this.name = new String(nome);
this.surname = new String(cognome);
this.age = eta;
}

public void adress(String indirizzo){
this.address = new String(indirizzo);
}
public void stampaPeople(){
System.out.println("nome: " + this.name + " cognome: " + this.surname + " la sua eta: " + this.age + " il suo indirizzo: " + this.address);
}
public String toString(){
return this.name + this.surname + this.age + this.address;
}
}

// classe student
package person;
import java.io.Serializable;
public class student extends people implements Serializable{
protected int matricola;
protected String facolta;
protected String corso;
protected int year;



public student (String nome, String cognome, int eta, int mat){
super(nome,cognome,eta);
this.matricola= mat;

}

public void infoCorso(String fac, String cor, int anno){
this.facolta = new String(fac);
this.corso = new String(cor);
this.year = anno;
}

public void stampaStudent(){
super.stampaPeople();
System.out.println( "la matricola del studente : "+ this.matricola + "\n fa il corso: "+
this.corso + " della sua facolta: "+ this.facolta + " \nl'anno del corso: "+ this.year );

}

public String toString(){
return super.toString() + this.matricola + this.facolta + this.corso + this.year;
}

}
//classe readfile
package person;
import java.io.*;
import java.util.ArrayList;
public class readFile {


protected File f;

public readFile(String name){
this.f = new File(name);

}

public ArrayList <student> letturaFile(){
ArrayList <student> stu = new ArrayList<student>();

try{
student s;
FileInputStream fis = new FileInputStream(this.f);
ObjectInputStream ois = new ObjectInputStream(fis);


while((s=(student)ois.readObject()) !=null){
s.stampaStudent();
stu.add(s);
}
ois.close();
fis.close();
}
catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
catch(IOException e){
System.out.println("errore nel apertura di file");
}
return stu;
}
}

// clase writefile
package person;
import java.io.*;
import java.util.ArrayList;
public class writeFile {

File f;

public writeFile(String name){
this.f = new File(name);
}

public void insertOutput(ArrayList<student> stu){
try{
FileOutputStream fs = new FileOutputStream(this.f);
//DataOutputStream dos = new DataOutputStream(fs);
ObjectOutputStream oos = new ObjectOutputStream(fs);
for (student temp : stu){
oos.writeObject(temp);
}

oos.close();
fs.close();
}
catch(IOException e){
System.out.println("errore di scrittura nel file:"+ this.f.getName());
}

}
public void insertOutput(student s){
try{
FileOutputStream fs = new FileOutputStream(this.f);
//DataOutputStream dos = new DataOutputStream(fs);
ObjectOutputStream oos = new ObjectOutputStream(fs);
oos.writeObject(s);
oos.close();
fs.close();
}
catch(IOException e){
System.out.println("errore di scrittura nel file:"+ this.f.getName());
}

}

}

//classe main
package person;
import java.util.ArrayList;
import java.util.Scanner;
public class mainClass {


public static void main(String args[]){

/* Scanner scan = new Scanner(System.in);
ArrayList <student> stu = new ArrayList <student>();
for ( int i =0; i < 3; i++){
String tempNome, tempCognome;
int tempEta, tempMat;
System.out.println("inseriisci nel ordine nome cognome eta mat: ");
tempNome =scan.nextLine();
tempCognome = scan.nextLine();
tempEta= scan.nextInt();
tempMat = scan.nextInt();
student temp = new student(tempNome, tempCognome, tempEta, tempMat);

System.out.println("inserisic informazione del corso nel ordine: facolta, corso ,anno: ");
String tempFac =new String();
String tempCor = new String();
tempFac = scan.nextLine();
scan.nextLine();
tempCor = scan.nextLine();
int tempAnno;
tempAnno = scan.nextInt();
scan.nextLine();
temp.infoCorso(tempFac, tempCor, tempAnno);

System.out.println("inserisci indirizzo del studente : ");
String tempAdre;
tempAdre = scan.nextLine();
temp.adress(tempAdre);
stu.add(temp);
}

for (student item : stu){
item.stampaStudent();
}
writeFile wf = new writeFile("/home/neptune/Scrivania/primo_file.dat");
wf.insertOutput(stu);
*/
ArrayList <student> stu = new ArrayList<student>();
readFile rf = new readFile("/home/neptune/Scrivania/primo_file.dat");
stu=rf.letturaFile();
for (student item : stu){
item.stampaStudent();
}

}
}