Programming

How Are CRUD Operations Used for File Handling in

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Java is a high-level language. Java programs generally execute on a terminal that is not stored; some programs need some source to store information fetched from the program that is in the form of a file. CRUD operations stand for Create, Read, Update and Delete.

As said, some Java programs need some files to store information fetched from the program. A file stores different types of information, including text, images, videos, and more.

We can perform many operations on File:

  •  Creation
  •  Opening
  •  Reading
  •  Writing
  •  Moving
  •  Closing

Let us discuss CRUD operations in a better way by using example codes.

CRUD Operations

CRUD stands for Create, Read/ Retrieve, Update and Delete; these are used in file handling in Java. Creation of a file is done using POST, Reading of the file is done using GET, Updating the file using PUT, and for deleting a file, we use DELETE.

Now let us discuss each of the operations with an example using Java. 

Firstly, Let us discuss the Creation of the file:

  •  For creating a file in Java, we use the createNewFile() method.
  •  It returns a boolean value that is TRUE if the file is created successfully; else returns FALSE.

Code:

import java.io.File;  

import java.io.IOException;   

 class cfile {  

               public static void main(String args[]) {  

               try {  

                       File file = new File("C:JavaPrograms/sample.txt");   

                       if (file.createNewFile()) {  

                                  System.out.println("File " + file.getName() + " is created successfully.");  

                       } else {  

                                  System.out.println("File is already exists");  

                       }  

                     } catch (IOException exception) {  

                              System.out.println("Exception Occurred");  

                  }   

        }  

} 

Output: 

File sample.txt is created successfully.

Let us create another file for better understanding.

import java.io.File;  

import java.io.IOException;   

 class cfile1 {  

               public static void main(String args[]) {  

               try {  

                       File file = new File("C:JavaPrograms/sample1.txt");   

                       if (file.createNewFile()) {  

                                  System.out.println("File " + file.getName() + " is created successfully.");  

                       } else {  

                                  System.out.println("File is already exists");  

                       }  

                     } catch (IOException exception) {  

                              System.out.println("Exception Occurred");  

                  }   

        }  

} 

Output: 

File sample1.txt is created successfully.

Now, let us discuss Reading or Retrieving the file.

For reading or retrieving a file in Java, we use the Scanner class and which helps to read the contents of the file.

Code:

import java.io.File;   

import java.io.FileNotFoundException;   

import java.util.Scanner;   

class rfile {  

    public static void main(String[] args) {  

        try {  

            File file = new File("C:JavaPrograms/sample.txt");    

            Scanner dataReader = new Scanner(file);  

            while (dataReader.hasNextLine()) {  

                String fileData = dataReader.nextLine();  

                System.out.println(fileData);  

            }  

            dataReader.close();  

        } catch (FileNotFoundException exception) {  

            System.out.println("Exception Occurred");    

        }  

    }  

}  

Output: 

#Reads file from the mentioned location.

This is a Java file used as a sample!

One more example for reading sample1.text file.

Code:

import java.io.File;   

import java.io.FileNotFoundException;   

import java.util.Scanner;   

class rfile1 {  

    public static void main(String[] args) {  

        try {  

            File file = new File("C:JavaPrograms/sample1.txt");    

            Scanner dataReader = new Scanner(file);  

            while (dataReader.hasNextLine()) {  

                String fileData = dataReader.nextLine();  

                System.out.println(fileData);  

            }  

            dataReader.close();  

        } catch (FileNotFoundException exception) {  

            System.out.println("Exception Occurred");    

        }  

    }  

}  

Output: 

#Reads file from the mentioned location.

This is a Java file, used as a sample1, for better understanding!

Now, let us discuss writing or Updating the file,

For writing or updating a file in Java, we use the FileWriter class with the write() method and use it to write or update some content to the file.

Code:

import java.io.FileWriter;   

import java.io.IOException;   

class ufile {  

    public static void main(String[] args) {  

    try {  

        FileWriter fwrite = new FileWriter("C:JavaPrograms/sample.txt");  

        fwrite.write("I’m updating the file with this statement!");   

        fwrite.close();   

        System.out.println("Content is successfully wrote to the file.");  

    } catch (IOException e) {  

            System.out.println("Exception Occurred");     

        }  

    }  

}  

Output: 

#Updates file from the mentioned location.

I’m updating the file with this statement!

Now Updating the sample1.txt file,

import java.io.FileWriter;   

import java.io.IOException;   

class ufile {  

    public static void main(String[] args) {  

    try {  

        FileWriter fwrite = new FileWriter("C:JavaPrograms/sample.txt");  

        fwrite.write("I’m updating the file with this statement!");   

        fwrite.close();   

        System.out.println("Content is successfully wrote to the file.");  

    } catch (IOException e) {  

            System.out.println("Exception Occurred");     

        }  

    }  

}  

Output: 

#Updates file from the mentioned location.

I’m updating the sample1 file with this statement!

Now, let us discuss deleting the file.

For deleting a file in Java, we use the delete() method, which is used to delete files.

Code:

import java.io.File;   

class DeleteFile {  

  public static void main(String[] args) {   

    File file= new File("C:JavaPrograms/sample.txt");   

    if (file.delete()) {   

      System.out.println(file.getName()+ " file is deleted successfully.");  

    } else {  

            System.out.println("Error Occurred");    

 

    }   

  }   

}  

Output: 

#Deletes file from the mentioned location.

sample.txt file is deleted successfully.

Now let us delete the sample1.txt file from the JavaPrograms folder in the C drive.

Code:

import java.io.File;   

class DeleteFile {  

  public static void main(String[] args) {   

    File file= new File("C:JavaPrograms/sample1.txt");   

    if (file.delete()) {   

      System.out.println(file.getName()+ " file is deleted successfully.");  

    } else {  

            System.out.println("Error Occurred");    

 

    }   

  }   

}  

Output: 

#Deletes file from the mentioned location.

sample1 .txt file is deleted successfully.

File Handling in Java

We have some streams in Java used for performing input-output operations on files. Stream is nothing but the sequence of data.

Here we have two types of streams in Java:

  1. Input Stream
  2. Output Stream

In Java, we also have some file class methods like createNewFile(), canRead(), canWrite(), delete(), and more.

Conclusion

  1. We discussed how CRUD operations are used in Java.
  2. Also discussed why CRUD operations are used in Java.
  3. CRUD operations are Create, Read, Update and Delete.
  4. Basically, CRUD operations are used to handle files in Java.
  5. C for Creating a file is used for creating a file using Java.
  6. R for Reading or Retrieving a file for reading a file using Java.
  7. U for Updating the file using Java.
  8. D for Deleting the file using Java.
  9. We can perform many other operations on files using Java.
  10. We discussed the different examples using Java Programs for a better understanding of concepts. 

I hope this blog was informative.



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