JAVA Streams and Writers:

FILE HANDLING INTRODUCTION

Provided "input.csv" which has User details. Read all the user information stored in CSV format and create a user object by parsing the line. Add all the user objects to the ArrayList. At last, display the user list.

Output format:

Use "%-15s %-20s %-15s %s\n" to print statements for the heading of the details in the Main method.

Sample Output :

Name            Email                Username        Password
William             will@gmail.com        william             will123
john           john@gmail.com     john           abc

CODE:

public class User{
    
    private String name;
    private String email;
    private String username;
    private String password;

    public User(){}
    
public User(String name, String email, String username, String password) {
        super();
        this.name = name;
        this.email = email;
        this.username = username;
        this.password = password;   
}
    
public String getName() {
    return name;
}
    
public void setName(String name) {
    this.name = name;
}
    
public String getEmail() {
    return email;
}
    
public void setEmail(String email) {
    this.email = email;
}
    
public String getUsername() {
    return username;
}
    
public void setUsername(String username) {
    this.username = username;
}
    
public String getPassword() {
    return password;
}
    
public void setPassword(String password) {
    this.password=password;
}
}

import java.io.*;
import java.util.*;

public class UserBO {
    List<User> list = new ArrayList<User>();
String str = new String();

public List<User> readFromFile(BufferedReader br) throws IOException {
while ((str = br.readLine()) != null) {
// str=str+br.readLine();
String records[] = str.split("\n");
for (int i = 0; i < records.length; i++) {
String values[] = (records[i]).split(",");
// System.out.println(values[0]);
User user = new User();
user.setName(values[0]);
user.setEmail(values[1]);
user.setUsername(values[2]);
user.setPassword(values[3]);
list.add(user);
values = null;

}
}
return list;
}

public void display(List<User> list) {
for(User user: list) {
System.out.printf("%-15s %-20s %-15s %s\n", user.getName(), user.getEmail(), user.getUsername(), user.getPassword());
}
}
}

import java.io.BufferedReader;
//import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void main(String[] args) throws IOException {
List<User> userList = null;
FileReader fr = new FileReader("input.csv");
BufferedReader br = new BufferedReader(fr);
UserBO ub = new UserBO();
try {
userList = ub.readFromFile(br);
//System.out.println(userList.size());
} catch (Exception e) {
System.out.println(e);
}finally {
br.close();
}
if(userList.isEmpty()) {
System.out.println("The list is empty");
}else {
String name = "Name", email="Email", username="Username", password="Password";
System.out.printf("%-15s %-20s %-15s %s\n", name, email, username, password);
ub.display(userList);
}
}
}

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