Java > File Permissions

File Permissions in Java

Java provides methods in the File class to check and modify file permissions such as read and write access. These methods help ensure security and control over file access.

Common File Permission Methods

Operation	Package	Class	Method
Check Read Access	java.io	File	canRead()
Check Write Access	java.io	File	canWrite()
Set Readable	java.io	File	setReadable(boolean)
Set Writable	java.io	File	setWritable(boolean)

Checking File Permissions

The canRead() and canWrite() methods check if a file is readable or writable, respectively.

Example: Checking File Permissions

package com.vvsk.fullstack.files;

import java.io.File;

public class CheckPermissionsExample {
    public static void main(String[] args) {
        File file = new File("example.txt");

        if (file.exists()) {
            System.out.println("Readable: " + file.canRead());
            System.out.println("Writable: " + file.canWrite());
        } else {
            System.out.println("File does not exist.");
        }
    }
}

Modifying File Permissions

The setReadable() and setWritable() methods modify file permissions.

Example: Modifying File Permissions

package com.vvsk.fullstack.files;

import java.io.File;
import java.io.IOException;

public class ModifyPermissionsExample {
    public static void main(String[] args) throws IOException {
        File file = new File("example.txt");
        
        // Create the file if it does not exist
        if (file.createNewFile()) {
            System.out.println("File created successfully.");
        }

        // Set read-only
        if (file.setReadable(true) && file.setWritable(false)) {
            System.out.println("File set to read-only mode.");
        } else {
            System.out.println("Failed to set permissions.");
        }

        // Revert to writable mode
        if (file.setWritable(true)) {
            System.out.println("File set back to writable mode.");
        } else {
            System.out.println("Failed to restore write permissions.");
        }
    }
}

Best Practices for File Permissions

✅ Always verify if a file exists before checking or modifying permissions.
✅ Use permissions carefully in security-sensitive applications.
✅ When setting permissions, consider platform-specific behavior for compatibility.

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