Demo object1 = new Demo(100,"saran");
Demo object2 = new Demo(20 ,"nivas");

ArrayList<Demo> list=new ArrayList<>();
try {
    FileOutputStream file=new FileOutputStream("C:\Users\SARANNIVAS\Documents\file\obj");
    ObjectOutputStream out=new ObjectOutputStream(file);
    list.add(object1);
    list.add(object2);
    out.writeObject(list);

    out.close();
    file.close();

    System.out.println("object has been serialized");

} catch(IOException ex)
{
     ex.printStackTrace();
    System.out.println("exception is caught");
}


try {
    FileInputStream file=new FileInputStream("C:\Users\SARANNIVAS\Documents\file\obj");
    ObjectInputStream in=new ObjectInputStream(file);
    ArrayList<Demo> list1=new ArrayList<>();
    list1=(ArrayList<Demo>)in.readObject();

    for(Demo d:list1) {
        System.out.println(d.a);
        System.out.println(d.b);
    }

} catch(IOException ex) {
    System.out.println("IOException is caught");
}

public static void main(String... args) {
    Demo object1 = new Demo(100, "saran");
    Demo object2 = new Demo(20, "nivas");

    serialize(object1, object2);

    List<Demo> collections = load();

    //search
    List<Demo> result = search(collections, "saran");
    //match result
    if (Objects.nonNull(result))
        result.stream().forEach(System.out::println);

}

public static List<Demo> search(List<Demo> collections, String name) {
    if (Objects.isNull(collections) || collections.isEmpty()) return null;
    return collections.stream().filter(itm -> itm.b.equals(name)).collect(Collectors.toList());
}

public static void serialize(Demo... objects) {
    try {
        FileOutputStream file = new FileOutputStream("/home/jst/obj");
        ObjectOutputStream out = new ObjectOutputStream(file);
        if (Objects.nonNull(objects)) {
            List<Demo> collect = Arrays.stream(objects).collect(Collectors.toList());
            out.writeObject(collect);
            out.close();
            file.close();
            System.out.println("object has been serialized");
        }
    } catch (
            IOException ex) {
        ex.printStackTrace();
        System.out.println("exception is caught");
    }
}

public static List<Demo> load() {
    try {
        FileInputStream file = new FileInputStream("/home/jst/obj");
        ObjectInputStream in = new ObjectInputStream(file);
        return (ArrayList<Demo>) in.readObject();
    } catch (Exception ex) {
        System.out.println("IOException is caught");
        return null;
    }
}


public static class Demo implements Serializable {
    private int a;
    private String b;

    public Demo(int a, String b) {
        this.a = a;
        this.b = b;
    }

    public int getA() {
        return a;
    }

    public void setA(int a) {
        this.a = a;
    }

    public String getB() {
        return b;
    }

    public void setB(String b) {
        this.b = b;
    }

    @Override
    public String toString() {
        return "Demo{" +
                "a=" + a +
                ", b='" + b + ''' +
                '}';
    }
}