Day-78 Java File Handling

#webdev #programming #java

File handling in Java allows us to create, read, update, and delete files through built-in classes. Java provides powerful APIs to work with files and directories in the java.io package.

1. The File Class in Java

The File class (in java.io package) is used to represent file and directory pathnames. It does not directly deal with the content of files; instead, it provides methods to create, delete, and get file information.

2. Common Methods in the File Class

createNewFile() – Creates a new file
delete() – Deletes the file
canExecute() – Checks if file is executable
canRead() – Checks if file is readable
canWrite() – Checks if file is writable
exists() – Checks if file exists
getAbsolutePath() – Returns absolute path
getName() – Returns file name
isDirectory() – Checks if path is directory
isFile() – Checks if path is file
isHidden() – Checks if file is hidden
lastModified() – Returns last modified time
renameTo(File Name) – Renames file
setExecutable(boolean) – Sets executable permission
setReadable(boolean) – Sets readable permission
setWritable(boolean) – Sets writable permission
listFiles() – Lists files in a directory

3. File Reading and Writing

FileWriter and BufferedWriter

FileWriter is used to write characters to a file.
BufferedWriter provides efficient writing by buffering data.

FileReader and BufferedReader

FileReader reads characters from a file.
BufferedReader reads text efficiently and allows reading line by line.

4. Key Points

Always close streams or use try-with-resources for automatic closing.
BufferedReader and BufferedWriter improve performance.
File class is for metadata and file management, not content reading/writing.

5. Example Program

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class FileDemo {
    public static void main(String[] args) {
        File myFile = new File("D:\\Tamil\\Hi.txt");
        try {
            myFile.createNewFile();
            System.out.println("File created successfully.");

            FileWriter writer = new FileWriter(myFile, true);
            BufferedWriter bw = new BufferedWriter(writer);

            bw.write("Tamilselvan K");
            bw.newLine();
            bw.write("hii");
            bw.close();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

DEV Community