File Handling Concept in Java

File :-

File is a collection of records ,if we want to store program output permanently under computer hardisk then we prefer file handling program.

java provide io package to implement File Operation.


                                        File
 
    Text File                                            Binary File

.txt,.doc.xlsx,.pdf                                    .jpg,.png,.mp3,.mp4 etc


FileWriter                                             FileOutputStream
FileReader                                            FileInputStream
BufferedWriter                                   
BufferedReader


To Write  Data in File:-

public class FileHandlingProgram {
    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
        float p=12000;
        float r=2.2F;
        float t=2;
        float si= (p*r*t)/100;
     
        File f = new File("E://hello.txt");
        FileWriter fw = new FileWriter(f,true);
        BufferedWriter bw = new BufferedWriter(fw);
        bw.write("result is "+si);
        bw.newLine();
        System.out.println("Enter Content");
        String d = sc.nextLine();
        bw.write(d);
        bw.close();
     
    }
 
}

Read Operation in File:-

public class FileHandlingProgram {

    public static void main(String[] args) throws IOException {

     

        

        File f = new File("E://hello.txt");

        FileReader fw = new FileReader(f);

        BufferedReader bw = new BufferedReader(fw);

        String s="";

        String data="";

        while((s=bw.readLine())!=null)

        {

             data+=s;

            

        }

        System.out.println(data);

        bw.close();

        

    }

    

}

................................................................................................................................................

File Input/Output Example using Binary file:-

public class FileHandlingProgram {
    public static void main(String[] args) throws IOException {
   
        Scanner sc = new Scanner(System.in);
        File f = new File("E://hello.txt");
        FileOutputStream fout = new FileOutputStream(f);
        System.out.println("Enter data");
        String data = sc.nextLine();
        byte arr[] = data.getBytes();  //string to byte conversion
        fout.write(arr);
        fout.close();
       
    }
   
}

Program to Read Data From File:-

public class FileHandlingProgram {
    public static void main(String[] args) throws IOException {
   
        Scanner sc = new Scanner(System.in);
        File f = new File("E://hello.txt");
        FileInputStream fi = new FileInputStream(f);
       
        String data = " ";
        byte arr[] = new byte[1000];
        int x;
        while((x = fi.read(arr))!=-1)
        {
            String s = new String(arr);
            System.out.print(s);
        }
       
       
    }
   
}