title: whats wrong?(NumberFormatException: null)
body: <pre><code>    import java.io.*;
      class AccountInfo {
  
      private String lastName;
      private String firstName;
      private int age;
      private float accountBalance;
      protected AccountInfo(final String last,final String first,final int ag,final float balance) throws IOException{
  
          lastName=last;
          firstName=first;
          age=ag;
          accountBalance=balance;
      }
      public void saveState(final OutputStream stream){try{
  
          OutputStreamWriter osw=new OutputStreamWriter(stream);
          BufferedWriter bw=new BufferedWriter(osw);
          bw.write(lastName);
          bw.newLine();
          bw.write(firstName);
          bw.write(age);
          bw.write(Float.toString(accountBalance));
          bw.close();}
          catch(IOException e){
              System.out.println (e);
          }
      } 
      public void restoreState(final InputStream stream)throws IOException{
          try{
  
  
              InputStreamReader isr=new InputStreamReader(stream);
              BufferedReader br=new BufferedReader(isr);
              lastName=br.readLine();
              firstName=br.readLine();
              age=Integer.parseInt(br.readLine());
              accountBalance=Float.parseFloat(br.readLine());
              br.close();}
              catch(IOException e){
                  System.out.println (e);
          }
  
      }
  
  }
      class accounto{
          public static void main (String[] args) {try{
  
  
  
              AccountInfo obj=new AccountInfo("chaturvedi","aayush",18,18);
              FileInputStream fis=new FileInputStream("Account.txt");
              FileOutputStream fos=new FileOutputStream("Account,txt");
              obj.saveState(fos);
              obj.restoreState(fis);}
              catch(IOException e){
                  System.out.println (e);
          }
      }
  }
  </code></pre>
  
  <p>im getting the following error: Exception in thread "main" java.lang.NumberFormatException: null
      at java.lang.Integer.parseInt(Integer.java:454)
      at java.lang.Integer.parseInt(Integer.java:527)
      at AccountInfo.restoreState(accounto.java:43)
      at accounto.main(accounto.java:60)</p>