Can't store and load an arraylist in an object file

Can't store and load an arraylist in an object file

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Can't store and load an arraylist in an object file
Tag : java , By : user107506
Date : November 27 2020, 04:01 AM

I hope this helps you . Instead of writing the whole array to a file, write each element to a file. You have the right idea with the toString() override.
I would change the toString() as follows
public String toString() {
  return String.format("%s:%s:%f", nome, estado, montanteMax);
public void writeToFile(List<Aluno> objectList) {
   String data = objectList
                   .map(obj -> obj.toString())

public List<Aluno> readFile() throws IOException {
   List<Aluno> list = Files.readAllLines(Paths.get("utilizadores_objetos.txt"))
                      .filter(s -> !s.trim().isEmpty())
                      .map(s -> new Aluno(s))
   return list;
public Aluno(String data) {
   String items = data.split(":");
   nome = items[0];
   estado = items[1];
   montanteMax = Float.parseFloat(items[2]);

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How to store ArrayList<ArrayList<Object>> with Parcelable interface between Activities

Tag : android , By : adbanginwar
Date : March 29 2020, 07:55 AM
wish helps you You can iterate through ArrayList objects in its enclosing ArrayList and for each of this ArrayList objects you should use putParcelableArrayListExtra separately using different keys for each of them.

Read file, store content to an object, storing object in ArrayList causes java.lang.NullPointerException

Tag : java , By : Keonne Rodriguez
Date : March 29 2020, 07:55 AM
To fix this issue Your exception says that your error is located at tibianic.spy.system.FileHandler.addVipToList(FileHandler.java:81)
and based on your code it is thrown in the following method.
private void addVipToList(String name, String note) {
    Vip guy = new Vip(name,note);
public void setVipList(ArrayList<Vip> newList) {
    this.vip = newList;

JavaFX - Load Song object fields from text file into an ArrayList of Songs

Tag : java , By : n3txpert
Date : March 29 2020, 07:55 AM
like below fixes the issue The problems I was running into had to do with the fact that I was trying to implement code directly inside the Controller class. I need to implement all code inside some sort of method for the JavaFX controller.

How to load a csv file to an ArrayList <Object Type> while the other array is of strings?

Tag : java , By : pacorro2000
Date : March 29 2020, 07:55 AM
Hope this helps As explained in the comments, CSV-parsing is far from trivial, and should be delegated to a proven library.
This problem (reading, parsing, and data-binding) seems a perfect fit for Jackson's CSV Data format module:

how to load classes from a jar file and store it in an arraylist

Tag : java , By : appdelivery
Date : March 29 2020, 07:55 AM
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