File Handling in java

File Handling
In Java, file handling means working with files like creating them, reading data, writing data or deleting them. It helps a program save and use information permanently on the computer.

Main.java

package com.payilagam.controller;
import java.util.ArrayList;
import com.payilagam.service.Studentservice;
import com.payilagam.entity.Student;
import java.io.File;
import java.io.IOException;
import java.io.FileReader;
import java.io.FileNotFoundException;
public class Main{
public static void main(String[] args){
 File location = new File("/home/ezhil-abinaya-k/prp/java");

        File[] files = location.listFiles();

        for (File file : files) {
            System.out.println(file.getName());
        }
        for (File file : files) {
    if (file.isFile()) {
        System.out.println("File: " + file.getName());
    } else {
        System.out.println("Folder: " + file.getName());
    }
}
File file=new File("Ezhil.csv");
try{
  boolean created =file.createNewFile();
  System.out.println("created file");
  }catch(IOException io){
  System.out.println("Exception error");
}
try{
   FileReader reader=new FileReader(file);
   int i =reader.read();
   while(i!=-1){
  System.out.print((char)i);
  i=reader.read();
  }


}catch(FileNotFoundException obj){
    System.out.println("error-obj");
}
catch(IOException io){
  System.out.println("error-io");
}

}
}
Output:
Main.java
Supermarket.java
Studentservice.java
Student.class
Home.class
com
Studentservice.class
Main.class
Supermarket.class
Home.java
.git
Ezhil.csv
Student.java
File: Main.java
File: Supermarket.java
File: Studentservice.java
File: Student.class
File: Home.class
Folder: com
File: Studentservice.class
File: Main.class
File: Supermarket.class
File: Home.java
Folder: .git
File: Ezhil.csv
File: Student.java
created file
id,name,mark,course
1, Ezhil,java,90
2, Saru, python, 90
3, Kamali, react,88

Student.java

package com.payilagam.entity;
public class Student{
private int id;
private String name;
private String course;
private int mark;
public Student (int id, String name, String course, int mark){
 this.id=id;
 this.name=name;
 this.course=course;
 this.mark=mark;
}
public static void main(String[] args){

}
public int getId(){
return id;
}
public void setId(int id){
this.id=id;
}
public String getName(){
return name;
}
public void setName(String name){
this.name=name;
}
public String getCourse(){
return course;
}
public void setCourse(String course){
this.course=course;
}
public int getMark(){
return mark;
}
public void setMark(int mark){
this.mark=mark;
}
}

Studentservice.java

package com.payilagam.service;
import java.util.ArrayList;
import com.payilagam.entity.Student;
public class Studentservice {

    ArrayList<Student> students = new ArrayList<>();

    // Add Student
    public void addStudent(Student stud) {
        boolean addStatus=students.add(stud);
        if (addStatus){
        System.out.println("added success");
        } else{
        System.out.println("something went wrong");
        }
    }

    // View Students
    public ArrayList<Student> viewStudent() {
    for(Student student:students){
System.out.println(student.getId()+"-"+student.getName()+"-"+student.getCourse()+"-"+student.getMark());
 }
 return students;
 }

    // Search Student
    public void searchStudent(int id) {
    boolean found=false;
    for(Student student:students){
    if(student.getId()==id){
    System.out.println(student.getId()+"-"+student.getName()+"-"+student.getCourse()+"-"+student.getMark());found=true;
    }
    }if(found==false){
    System.out.println("not found...");
    }

        }



    // Update Student Mark
   public void updateStudent(int id, int newMark) {
    for(Student student : students) {
        if(student.getId() == id) {
            student.setMark(newMark);
            System.out.println("student updated successfully");
            return;
        }
    }
    System.out.println("student not found...");
}

    // Delete Student
    public void deleteStudent(int id) {
    boolean found=false;
    for (Student student:students){
    if(student.getId()==id){
    students.remove(student);
    System.out.println("student deleted successfully");
    found=true;
    break;
    }
    } 
    if(found==false){
    System.out.println("student not found...");
    }

    }


}

Reference
https://www.geeksforgeeks.org/java/file-handling-in-java/