title: Java - How to save an ArrayList into a file and open it?
body: <p>I made a class called Subject. The class consists of these lines:</p>
  
  <pre><code>    class Subject {
      int serial;
      Double credit, gpa, tgpa = 0.0;
  
      public Subject(int serial, Double credit, Double gpa, Double tgpa) {
          this.serial = serial;
          this.credit = credit;
          this.gpa = gpa;
          this.tgpa = tgpa;
      }
  
      public int getSerial() {
          return serial;
      }
  
      public void setSerial(int serial) {
          this.serial = serial;
      }
  
      public Double getCredit() {
          return credit;
      }
  
      public void setCredit(Double credit) {
          this.credit = credit;
      }
  
      public Double getGpa() {
          return gpa;
      }
  
      public void setGpa(Double gpa) {
          this.gpa = gpa;
      }
  
      public Double getTgpa() {
          return tgpa;
      }
  
      public void setTgpa(Double tgpa) {
          this.tgpa = tgpa;
      }
  }
  </code></pre>
  
  <p>I'm trying to create two methods for Saving the ArrayList of Subject into a file and Reopen it as an ArrayList of Subject.
  Any solution?</p>