Question

Write a Java Program, that opens the file "students.txt"

• The program must read the file line by line
• The program parses each line that it reads
• For example, for this line:

1:mohamed:ali:0504123456:cs102:cs202

• The program must print
•    >ID = 1
•    >First Name = Mohamed
•   >Last Name = Ali
•   >Mobie = 0504123456
•   >Courses = cs102, cs202
• In addition, it adds the mobile phone number into an ArrayList called studentPhoneList
• Print the content and the size of studentPhoneList

Show your results and provide your code.

txt file contain this

1:mohamed:ali:0504123456:cs102:cs202:cs330
2:ahmed:hamdi:0507415985:cs460:cs320
3:kamel:salem:0503245714:cs140
4:Mohsen:Mohamed:0503245714:cs140:cs150

simple code

Answer 1

Note the directory structure. I have a

Project
|->src
|->FileManupulation.java
|->students.txt

The java file and the text file are in same dierctory

FileManpulation.Java

package file.manupulation;

import java.io.IOException; //contains exceptions the input output exception handling
import java.nio.file.Files; //java.nio.file is the API to handle input output operation.It was included in JAVA 7
import java.nio.file.Path; //Contains operations for file paths
import java.nio.file.Paths; //Contains operation for file paths
import java.util.ArrayList; //to use the ArrayList
import java.util.List; // to use the List interface

class Student{ //student class stores individual student information
   public String id;
   public String firstName;
   public String lastName;
   public String mobile;
   public List<String> courses;
   public Student(String id,String firstName,String lastName,String mobile) { //the constructor. We don't add the courses through it
       this.id = id;
       this.firstName = firstName;
       this.lastName = lastName;
       this.mobile = mobile;
       this.courses = new ArrayList<String>();
   }  
}

public class FileManupulation {
   public static void main(String[] args) throws IOException {
       Path pathOfFile = Paths.get("./src/students.txt");           //"./src/students.txt" is relative path to the students.txt file. You can mention the absolute path instead.
       List<String> lines = Files.readAllLines(pathOfFile);        //stores all the content of the file as list of strings
       List<Student> students = new ArrayList<Student>();         //List of all the students
       List<String> studentPhoneList = new ArrayList<String>();    //this the list for storing the phone numbers
       for(String details:lines) {
           String[] components = details.split(":");                                               //we take out different components of the students using ":" as delimiter
           String firstName = components[1].substring(0, 1).toUpperCase() + components[1].substring(1);     //to make the first name start with upper case
           String lastName = components[2].substring(0, 1).toUpperCase() + components[2].substring(1);       //to make the last name start with upper case
           Student student = new Student(components[0],firstName,lastName,components[3]);                   //stores id,first name,last name,mobile
           studentPhoneList.add(components[3]);                               //store the phone number in studentPhoneList                      
           students.add(student);
           for(int i=4;i<components.length;i++)                   //adding the courses
               student.courses.add(components[i]);
       }
       /*printing all the student details*/
       for(Student student:students) {
           System.out.println(">Id = "+ student.id + "\n>First Name = " + student.firstName + "\n>Last Name = " + student.lastName + "\n>Mobile = " + student.mobile );
           System.out.print(">Courses = " + student.courses.get(0));
           for(int i=1;i<student.courses.size();i++)
               System.out.print(","+ student.courses.get(i));
           System.out.println("\n");
       }
          
      
   }
}

Refer to the below images for proper indentaion and output