How to add objects to HashSet from file using ObjectInputStream?





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I have an empty file.txt with users and I am using ObjectOutputStream for write object into file after that I want to add this element into HashSet. How can I do it?
This is my method for add element:



    Set<User> users = new HashSet<User>();
try {
Scanner scanner = new Scanner(file);
while (scanner.hasNext()){
String line = scanner.nextLine();
Scanner lineScanner = new Scanner(line);
lineScanner.useDelimiter("\|");

String name = lineScanner.next();
String password = lineScanner.next();
String email = lineScanner.next();
String nameSurname = lineScanner.next();

User user = new User(name, password, email, nameSurname);
users.add(user);









share|improve this question























  • You rewrite the HashSet again to your file (which is not a txt file, but a binary file), to overwrite the old serialized HashSet by the new one

    – JB Nizet
    Nov 23 '18 at 11:05




















0















I have an empty file.txt with users and I am using ObjectOutputStream for write object into file after that I want to add this element into HashSet. How can I do it?
This is my method for add element:



    Set<User> users = new HashSet<User>();
try {
Scanner scanner = new Scanner(file);
while (scanner.hasNext()){
String line = scanner.nextLine();
Scanner lineScanner = new Scanner(line);
lineScanner.useDelimiter("\|");

String name = lineScanner.next();
String password = lineScanner.next();
String email = lineScanner.next();
String nameSurname = lineScanner.next();

User user = new User(name, password, email, nameSurname);
users.add(user);









share|improve this question























  • You rewrite the HashSet again to your file (which is not a txt file, but a binary file), to overwrite the old serialized HashSet by the new one

    – JB Nizet
    Nov 23 '18 at 11:05
















0












0








0








I have an empty file.txt with users and I am using ObjectOutputStream for write object into file after that I want to add this element into HashSet. How can I do it?
This is my method for add element:



    Set<User> users = new HashSet<User>();
try {
Scanner scanner = new Scanner(file);
while (scanner.hasNext()){
String line = scanner.nextLine();
Scanner lineScanner = new Scanner(line);
lineScanner.useDelimiter("\|");

String name = lineScanner.next();
String password = lineScanner.next();
String email = lineScanner.next();
String nameSurname = lineScanner.next();

User user = new User(name, password, email, nameSurname);
users.add(user);









share|improve this question














I have an empty file.txt with users and I am using ObjectOutputStream for write object into file after that I want to add this element into HashSet. How can I do it?
This is my method for add element:



    Set<User> users = new HashSet<User>();
try {
Scanner scanner = new Scanner(file);
while (scanner.hasNext()){
String line = scanner.nextLine();
Scanner lineScanner = new Scanner(line);
lineScanner.useDelimiter("\|");

String name = lineScanner.next();
String password = lineScanner.next();
String email = lineScanner.next();
String nameSurname = lineScanner.next();

User user = new User(name, password, email, nameSurname);
users.add(user);






java io set






share|improve this question













share|improve this question











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asked Nov 23 '18 at 11:01









Far112Far112

1




1













  • You rewrite the HashSet again to your file (which is not a txt file, but a binary file), to overwrite the old serialized HashSet by the new one

    – JB Nizet
    Nov 23 '18 at 11:05





















  • You rewrite the HashSet again to your file (which is not a txt file, but a binary file), to overwrite the old serialized HashSet by the new one

    – JB Nizet
    Nov 23 '18 at 11:05



















You rewrite the HashSet again to your file (which is not a txt file, but a binary file), to overwrite the old serialized HashSet by the new one

– JB Nizet
Nov 23 '18 at 11:05







You rewrite the HashSet again to your file (which is not a txt file, but a binary file), to overwrite the old serialized HashSet by the new one

– JB Nizet
Nov 23 '18 at 11:05














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