How to store the value of a variable in java after the end of the program?

Question

How to store the value of a variable in java after the end of the program

Answer 1

For this, you can use a Serializable .

In this case, you must create a file to store the information you want to save.

Here’s a simple example of how to record and retrieve an object.

This file will be saved to the application root.

Follows:

private static final File FILE= new File("MyObject.obj");


    /**
     * Salva um Serializable
     * @param object
     * @throws IOException
     */
    public static void save(MyObject object) throws IOException{
        final FileOutputStream fileOutputStream = new FileOutputStream(FILE);
        final ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
        objectOutputStream.writeObject(object);
        objectOutputStream.close();
        fileOutputStream.close();
    }

    /*
     * Carrega o Serializable 
     */
    public static MyObject load() throws IOException, ClassNotFoundException{
        final FileInputStream fileInputStream = new FileInputStream(FILE);
        final ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
        MyObject object = (MyObject)objectInputStream.readObject();
        objectInputStream.close();
        fileInputStream.close();
        return object;
    }




    /**
     * Objeto de exemplo, para que seja salvo é necessário implementar um Serializable
     */

    static class MyObject implements Serializable{
        /**
         * Serial é o identifica a versão da classe que será usada no processo de serializacão 
         */
        private static final long serialVersionUID = 1L;
        private String value;
        public String getValue() {
            return value;
        }
        public void setValue(String value) {
            this.value = value;
        }
    }