Write serializable object from Array

Question

I have a little problem with this thing. I tried to make an array where the user enters data, and the data needs to be saved in an object.obj file.

This is my code:

  import java.util.*;

  public class insertData implements java.io.Serializable 
{
      Scanner keyboard=new Scanner(System.in);
      private String One;
      private String Two;


      public void new()
      {
          System.out.println("How many lines do you want to insert?");
          int p=keyboard.nextInt();

          for (int i = 0; i < p; i++) 
          {
              One=keyboard.next();
              Two=keyboard.next();
          }
      }

      public String toString()
      {
        new();
        String text=One+"\t"+Two;
        return text;
      }

}

And the File class will be:

  import java.io.*;

  public class fileA 
  {
      insertData iD = new insertData()
      String a;
      ObjectOutputStream oos;
      ObjectInputStream ois;

      public void writeFile(File file)
     {
         try 
         {
              oos=new ObjectOutputStream(new FileOutputStream(file1));
              a=iD.toString();
              oos.writeObject(a);
              oos.close();

         } 
         catch (FileNotFoundException e) 
         {
             e.printStackTrace();
         } 
         catch (IOException e) 
         {
             e.printStackTrace();
         }
     }

     public void readFile(File file1)
     {
          try  
          {
                ois=new ObjectInputStream(new FileInputStream(file1));
                String str=(String)ois.readObject();
                System.out.println(str);
                ois.close();
          }
          catch (IOException ex) 
          {
            System.err.println(ex);
          }
          catch (ClassNotFoundException ex) 
          {
            System.err.println(ex);
          }

    }
  }

The problem is that this saves only the last line of data entered. The results should be:

Text1     Text2
aaaaa     bbbbb
ccccc     ddddd

@Eng.Fouad is right. You can't use java reserved keywords as method name. Which raises a doubt on how you could execute the program in the first place. You must have got compiler errors. — Ravi Trivedi
– Ravi Trivedi, Commented May 16, 2013 at 0:49
(Off-topic, but some friendly Java advice: you should use UppercaseStartingCamelCase for class names (eg FileA not fileA and InsertData not insertData). Your method names follow the correct conventional already). — Greg Kopff
– Greg Kopff, Commented May 16, 2013 at 0:51

greedybuddha · Accepted Answer · 2013-05-16 01:04:36Z

1

The issue is that you only have one One and Two so when you go over this loop.

for (int i = 0; i < p; i++) 
{
    One=keyboard.next();
    Two=keyboard.next();
}

you are overwriting the values. So that is why you are only getting the last values.

What you need to do is either store these elements in a collection.

List<String> ones = new ArrayList<String>();
List<String> twos = new ArrayList<String>();
...
for (int i = 0; i < p; i++) 
{
    ones.add(keyboard.next());
    twos.add(keyboard.next());
}

or you can append to a buffer.

StringBuilder sb = new StringBuilder();
...
for (int i = 0; i < p; i++) 
{
    sb.append(keyboard.next()+"    " +keyboard.next()+"\n");
}

Then just write out to the file appropriately

answered May 16, 2013 at 1:04

greedybuddha

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2 Comments

user2328079 Over a year ago

Thanks for your answer @greedybuddha. I finally get to solve the problem. I was an "+=" problem for append the text. PS: main class was omitted on purpose because the problem couldn't be there and new() it was just an example... ;-) Thanks again for your help. Problem solved!

greedybuddha Over a year ago

No problem, the += is a solution that works as well. It's doing the same thing as the StringBuilder but directy, (and a bit less efficiently ;) ).

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