New version of the article

core-java-modules/core-java-nio-2/README.md

@@ -8,4 +8,5 @@ This module contains articles about core Java non-blocking input and output (IO)
 - [Create a Symbolic Link with Java](https://www.baeldung.com/java-symlink)
 - [Introduction to the Java NIO Selector](https://www.baeldung.com/java-nio-selector)
 - [Using Java MappedByteBuffer](https://www.baeldung.com/java-mapped-byte-buffer)
+- [How to Lock a File in Java](https://www.baeldung.com/how-to-lock-a-file-in-java)
 - [[<-- Prev]](/core-java-modules/core-java-nio)

core-java-modules/core-java-nio-2/pom.xml

@@ -14,22 +14,5 @@
         <version>0.0.1-SNAPSHOT</version>
         <relativePath>../../parent-java</relativePath>
     </parent>
-    
-    <dependencies>
-    	<!-- https://mvnrepository.com/artifact/com.github.jnr/jnr-ffi -->
-		<dependency>
-		    <groupId>com.github.jnr</groupId>
-		    <artifactId>jnr-ffi</artifactId>
-		    <version>2.1.11</version>
-		</dependency>
-		    	
-		<!-- https://mvnrepository.com/artifact/com.github.jnr/jnr-constants -->
-		<dependency>
-		    <groupId>com.github.jnr</groupId>
-		    <artifactId>jnr-constants</artifactId>
-		    <version>0.9.14</version>
-		</dependency>
-				
-    </dependencies>
 
 </project>

core-java-modules/core-java-nio-2/src/main/java/com/baeldung/lock/com_baeldung_lock_FileLocks.h

@@ -1,21 +0,0 @@
-/* DO NOT EDIT THIS FILE - it is machine generated */
-#include <jni.h>
-/* Header for class com_baeldung_lock_FileLocks */
-
-#ifndef _Included_com_baeldung_lock_FileLocks
-#define _Included_com_baeldung_lock_FileLocks
-#ifdef __cplusplus
-extern "C" {
-#endif
-/*
- * Class:     com_baeldung_lock_FileLocks
- * Method:    getpid
- * Signature: ()J
- */
-JNIEXPORT jlong JNICALL Java_com_baeldung_lock_FileLocks_getpid
-  (JNIEnv *, jclass);
-
-#ifdef __cplusplus
-}
-#endif
-#endif

core-java-modules/core-java-nio-2/src/test/java/com/baeldung/lock/FileLocksTest.java

@@ -0,0 +1,78 @@
+package com.baeldung.lock;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.nio.channels.FileLock;
+import java.nio.channels.NonReadableChannelException;
+import java.nio.channels.NonWritableChannelException;
+
+import org.junit.jupiter.api.Test;
+
+class FileLocksTest {
+
+	// Exclusive locks
+	/**
+	 * Getting an exclusive (write) lock on the entire file.
+	 * Fails when getting the lock from a FileChannel obtained through a FileInputStream.
+	 */
+	@Test
+	void givenAnInputStream_whenGetWriteLock_throwNonWritableChannelException() {
+		assertThrows(NonWritableChannelException.class, 
+				() -> FileLocks.getExclusiveLockFromInputStream());
+	}
+	
+	/**
+	 * Getting and exclusive lock from a RandomAccessFile
+	 * @throws IOException
+	 */
+	@Test
+	void givenARandomAccessFileWithReadWriteAccess_whenGetWriteLock_lock() throws IOException {
+		FileLock lock = FileLocks.getExclusiveLockFromRandomAccessFile(0, 10);
+		assertNotNull(lock);
+		assertFalse(lock.isShared());
+	}
+	
+	/**
+	 * Getting an exclusive lock from FileChannel::open
+	 * @throws IOException
+	 */
+	@Test
+	void givenAPath_whenGetExclusiveLock_lock() throws IOException {
+		FileLock lock = FileLocks.getExclusiveLockFromFileChannelOpen(0, 10);
+		assertNotNull(lock);
+		assertFalse(lock.isShared());
+	}
+	
+	
+	/**
+	 * Getting a shared (read) lock works fine when getting the lock from a FileChannel obtained through a FileInputStream.
+	 * @throws IOException
+	 */
+	@Test
+	void givenAnInputStream_whenGetSharedLock_lock() throws IOException {
+		FileLock lock = FileLocks.getReadLockFromInputStream(0, 10);
+		assertNotNull(lock);
+		assertTrue(lock.isShared());
+		
+	}
+	
+	
+	@Test
+	void givenAFileOutputStream_whenGetSharedLock_throwNonReadableChannelException() {
+		assertThrows(NonReadableChannelException.class, 
+				() -> FileLocks.getReadLockFromOutputStream(0, 10));
+	}
+	
+	@Test
+	void givenARandomAccessFile_whenGetSharedLock_lock() throws IOException {
+		FileLock lock = FileLocks.getReadLockFromRandomAccessFile(0,  10);
+		assertNotNull(lock);
+		assertTrue(lock.isShared());
+		
+	}
+
+}