In Java How to make a File ReadOnly or Writable? How to create new file? How to check if file is Writable or not?

In Java how to make file Read only or Writable? Also, how to check if file is Writable or not?

In this tutorial we will go over below different File Operations.

• file.createNewFile()
• file.canWrite()
• file.setWritable(true)
• file.setReadOnly()

If you have any of below questions then you are at right place.

• Why can we change the file attributes of a read-only file in Java?
• How to change file permission to Read-Only in Linux or MacOS?
• Can I set a file to read-only in Java?
• How to open a file as read-only with java?

Create Java class: CrunchifyFileReadOnlyWritable.java

package crunchify.com.java.tutorials;

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

/**
 * @author Crunchify.com
 * In Java How to make a File ReadOnly or Writable? How to check if file is Writable or not?
 */

public class CrunchifyFileReadOnlyWritable {
        
        public static void main(String[] args) throws IOException {
                
                try {
                        
                        // Let's make file Read Only
                        crunchifyReadOnly();
                        Thread.sleep(10000);
                        
                        // Let's double check if file is Writable or not?
                        crunchifyIsFileWritable();
                        Thread.sleep(10000);
                        
                        // Let's make file Writable
                        crunchifyMakeWritable();
                        Thread.sleep(10000);
                        
                        // Let's double check if file is Writable or not?
                        crunchifyIsFileWritable();
                        
                        // Extra code to create new file in Java. By default it will be writable.
                        File file = new File("/Users/app/Download/newCrunchify.txt");
                        try {
                                
                                // createNewFile() - Atomically creates a new, empty file named by this abstract pathname if and only if a file with this name does not yet exist.
                                // The check for the existence of the file and the creation of the file if it does not exist are a single
                                // operation that is atomic with respect to all other filesystem activities that might affect the file.
                                // Note: this method should not be used for file-locking, as the resulting protocol cannot be made to work reliably. The FileLock facility should be used instead.
                                boolean newCrunchifyFile = file.createNewFile();
                        } catch (IOException e) {
                                e.printStackTrace();
                        }
                        
                } catch (InterruptedException e) {
                        e.printStackTrace();
                }
                
        }
        
        private static void crunchifyReadOnly() {
                File crunchifyFile = new File("/Users/app/Download/crunchify.txt");
                
                // setReadOnly90 - Marks the file or directory named by this abstract pathname so that only read operations are allowed.
                // After invoking this method the file or directory will not change until it is either deleted or marked to allow write access.
                // On some platforms it may be possible to start the Java virtual machine with special privileges that allow it to modify files that are marked read-only.
                // Whether or not a read-only file or directory may be deleted depends upon the underlying system.
                
                //      Let's make file ReadOnly.
                boolean crunchifyCheck = crunchifyFile.setReadOnly();
                
                if (crunchifyCheck) {
                        crunchifyPrint("Aaha.. File is ReadOnly now..");
                        
                } else {
                        
                        crunchifyPrint("Oops.. setReadOnly() operation failed..");
                }
        }
        
        private static void crunchifyIsFileWritable() {
                File crunchifyFile = new File("/Users/app/Download/crunchify.txt");
                
                // canWrite() -  Tests whether the application can modify the file denoted by this abstract pathname.
                // On some platforms it may be possible to start the Java virtual machine with special privileges that allow it to modify files that are marked read-only.
                // Consequently this method may return true even though the file is marked read-only.
                
                //      Let's check if file is Writable or not.
                boolean crunchifyCheck = crunchifyFile.canWrite();
                
                if (crunchifyCheck) {
                        crunchifyPrint("Checking.. Aaha.. File is writable now..");
                        
                } else {
                        
                        crunchifyPrint("Checking.. Oops.. File is readonly :(");
                }
        }
        
        private static void crunchifyMakeWritable() {
                File crunchifyFile = new File("/Users/app/Download/crunchify.txt");
                
                // setWritable() - A convenience method to set the owner's write permission for this abstract pathname.
                // On some platforms it may be possible to start the Java virtual machine with special privileges that allow it to modify files that disallow write operations.
                // An invocation of this method of the form file.setWritable(arg) behaves in exactly the same way as the invocation.
                
                //  Let's make file Writable.
                boolean crunchifyCheck = crunchifyFile.setWritable(true);
                
                if (crunchifyCheck) {
                        crunchifyPrint("File is writable now..");
                        
                } else {
                        
                        crunchifyPrint("Oops.. File is readonly..");
                }
        }
        
        // Crunchify's simple Print utility.
        private static void crunchifyPrint(String s) {
                System.out.println(s);
        }
}

Here is a list of all Java File() Operations:

Just run above program as a Java Application and you will see IntelliJ console result as below.

Console result:

Aaha.. File is ReadOnly now..
Checking.. Oops.. File is readonly..

File is writable now..
Checking.. Aaha.. File is writable..

Process finished with exit code 0

Let me know if you face any issue running above Java Program.

---

Example-2.

Another simple Java program to make file readonly. This program creates a File object representing a file called “crunchify.json” in the current directory.

It first checks if the file exists, and if it does, it makes the file read-only using the setReadOnly() method.

If the operation is successful, it prints “File is now read-only.” Otherwise, it prints “Failed to make file read-only.” Please note that depending on the file system, the readonly property may not be supported or may be ignored.

package crunchify.com.java.tutorials;

import java.io.File;

public class CrunchifyFileReadOnly {
    public static void main(String[] args) {
        File crunchifyFile = new File("/Users/app/Downloads/crunchify.json");

        // Check if the crunchifyFile exists
        if (!crunchifyFile.exists()) {
            System.out.println("File does not exist.");
            return;
        }

        // Make the crunchifyFile read-only
        if (crunchifyFile.setReadOnly()) {
            System.out.println("File is now read-only.");
        } else {
            System.out.println("Failed to make crunchifyFile read-only.");
        }
    }
}

IntelliJ IDEA console result

File is now read-only.

Process finished with exit code 0

Let me know if you face any issue running this code.

The post In Java How to make a File ReadOnly or Writable? How to create new file? How to check if file is Writable or not? appeared first on Crunchify.