Saving Object to File and then retrieving it agian

[ConnorSG1]

I am trying to save an object named car1 of a class named car(only contains one String valiable Colour) to file and then retrieve it again however this is what i get:

java.io.NotSerializableException: SaveEntireObjectToFile.Car
at java.io.ObjectOutputStream.writeObject0(ObjectOutp utStream.java:1180)
at java.io.ObjectOutputStream.writeObject(ObjectOutpu tStream.java:346)
at SaveEntireObjectToFile.Main.writeObject(Main.java: 41)
at SaveEntireObjectToFile.Main.main(Main.java:121)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.intellij.rt.execution.application.AppMain.main (AppMain.java:120)

Exception in thread "main" java.lang.NullPointerException
at SaveEntireObjectToFile.Main.readObject(Main.java:1 08)
at SaveEntireObjectToFile.Main.main(Main.java:124)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.intellij.rt.execution.application.AppMain.main (AppMain.java:120)


I think the problem lies with retrieving the object. Thanks for any help, my code is below:

public class Main
{
   //create an instance of the Car class named car1;
   static Car car1;
   static Car car2;



   public static void writeObject()
   {

      //start a fileOutputStream object;
      FileOutputStream saveFile = null;

      //start a ObjectOutputStream object;
      ObjectOutputStream saveObject = null;

      //store the name of the file to save to in myObjectFile;
      String myObjectFile = "ObjectFile.txt";

      try
      {
         //create a fileOutPutStream to link to a file to write to, named objectFile.txt
         saveFile = new FileOutputStream("object.txt");

         //create an objectOutputStream to place objects into save file
         saveObject = new ObjectOutputStream(saveFile);

         //write a complete object to objectOutputStream using writeObject() method;
         saveObject.writeObject(car1);
      } //end of try;

      catch (FileNotFoundException ex)
      {
         System.out.println("Sorry file not found");
      } //end of catch;

      catch(IOException ex)
      {
         ex.printStackTrace();
      } //end of catch;

      //everything in the following will always be executed regardless;
      finally
      {
         try
         {
            //if there is something in the file to send;
            if (saveObject !=null)
            {
               //flush the output stream before closing the file;
               saveObject.flush();
               //close the door behind me;
               saveObject.close();
            }//end of if statement;
         } //end of try statement;

         catch(IOException ex)
         {
            ex.printStackTrace();
         } //end of catch statement;

      } //end of finally statement;

   } //end of method;




   public static void readObject()
   {
      FileInputStream readFile = null;

      ObjectInputStream getObject = null;

      try
      {
         //open file to read from, named ObjectFile.txt;
         readFile = new FileInputStream("ObjectFile.txt");

         //create an ObjectInputStream to get objects from readFile;
         getObject = new ObjectInputStream(readFile);

         car2 = (Car)getObject.readObject();

         //close File (This also closes saveFile);
         getObject.close();

      }//end of try;

      catch(Exception exc)
      {
         System.out.println("Sorry there was an error");
      }//end of catch;


      System.out.println(car2.toString());

   }//end of method;





   public static void main(String[] args)
   {
       car1 = new Car("Red");

      //write it to a file;
      writeObject();

      //read the complete object back in from the new Car object;
      readObject();

   }//main
}//class

[bigsonny]

How are you "retrieving" it without a return statement?

Also, would you paste the class Car?

[Tolls]

The first exception says what the problem is.
You cannot write an object anywhere unless the class is Serializable (ie implements Serializable).