Assessment Test Question 16

Question List

Question: Which lines can the of the following program print out?

  1 import java.io.*;
  2 class Channel implements Serializable {}
  3 public class TV implements Serializable {
  4   private String brand;
  5   private transient int year;
  6   private Channel channel;
  7   public String getBrand() {return this.brand;}
  8   public void setBrand(String brand) {this.brand = brand;}
  9   public int getYear() { return year;}
 10   public void setYear(int year) { this.year = year;}
 11   public Channel getChannel() { return channel;}
 12   public void setChannel(Channel channel) {this.channel = channel;}
 13   public static void main(String[] args) throws Exception {
 14     try(ObjectOutputStream out = new ObjectOutputStream(
 15       new BufferedOutputStream(new FileOutputStream("tv.dat")))){
 16       TV tv = new TV();
 17       tv.setBrand("jee");
 18       tv.setYear(2009);
 19       tv.setChannel(new Channel());
 20       out.writeObject(tv);}
 21     try(ObjectInputStream in = new ObjectInputStream(
 22       new BufferedInputStream(new FileInputStream("tv.dat")))){
 23       TV tv = (TV)in.readObject();
 24       System.out.println(tv.getBrand());
 25       System.out.println(tv.getYear());
 26       System.out.println(tv.getChannel());
 27     }}}

Choice:
A. jee
B. empty line
C. 2009
D. 0
E. Channel@1540e19d
F. null
G. The code does not compile
H. The code compiles but throw exceptions at runtime



Next Question

Answer: A, D, E

Explain: The code compiles and runs without problem. Variable year is marked as transient. transient means the value won't be included in the serialization process, so year won't be in the serialized file. During deserialization, fields marked with transient will be ignored, no class constructor or default initializations are used. The year get default value 0.

Study: Use BufferedReader, BufferedWriter, File, FileReader, FileWriter, FileInputStream, FileOutputStream, ObjectOutputStream, ObjectInputStream, and PrintWriter in the java.iopackage.