some refactorings and prevent possible nullpointer exception

pom.xml

@@ -74,6 +74,7 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<java.version>1.7</java.version>
+		<spring-javaformat-maven-plugin.version>0.0.9</spring-javaformat-maven-plugin.version>
 	</properties>
 
 	<build>
@@ -89,6 +90,11 @@
                   <failOnNoGitDirectory>false</failOnNoGitDirectory>
                 </configuration>
 			</plugin>
+			<plugin>
+				<groupId>io.spring.javaformat</groupId>
+				<artifactId>spring-javaformat-maven-plugin</artifactId>
+				<version>${spring-javaformat-maven-plugin.version}</version>
+			</plugin>
 		</plugins>
 	</build>
 

src/main/java/locksdemo/JdbcLockService.java

@@ -32,7 +32,6 @@
 
 /**
  * @author Dave Syer
- *
  */
 public class JdbcLockService implements LockService {
 
@@ -42,10 +41,15 @@ public class JdbcLockService implements LockService {
 	private long expiry = 30000; // 30 seconds
 
 	private RowMapper<Lock> rowMapper = new LockRowMapper();
+
 	private String findAllQuery = "SELECT NAME,VALUE,EXPIRES FROM LOCKS";
+
 	private String createQuery = "INSERT INTO LOCKS (NAME,VALUE,EXPIRES) VALUES (?,?,?)";
+
 	private String deleteQuery = "DELETE FROM LOCKS WHERE NAME=? AND VALUE=?";
+
 	private String refreshQuery = "UPDATE LOCKS SET EXPIRES=? WHERE NAME=? AND VALUE=?";
+
 	private String findOneByNameQuery = "SELECT NAME,VALUE,EXPIRES FROM LOCKS WHERE NAME=?";
 
 	public JdbcLockService(DataSource dataSource) {
@@ -69,8 +73,8 @@ public Lock create(String name) throws LockExistsException {
 				throw new LockExistsException();
 			}
 		}
-		lock = new Lock(name, UUID.randomUUID().toString(), new Date(
-				System.currentTimeMillis() + expiry));
+		lock = new Lock(name, UUID.randomUUID().toString(),
+				new Date(System.currentTimeMillis() + expiry));
 		jdbcTemplate.update(createQuery, lock.getName(), lock.getValue(),
 				lock.getExpires());
 		return lock;
@@ -80,34 +84,37 @@ public Lock create(String name) throws LockExistsException {
 	@Transactional(isolation = Isolation.REPEATABLE_READ)
 	public boolean release(String name, String value) throws LockNotHeldException {
 		Lock lock = getLock(name);
-		if (lock!=null) {
+		if (lock != null) {
 			if (!lock.getValue().equals(value)) {
 				throw new LockNotHeldException();
 			}
 			if (lock.isExpired()) {
 				throw new LockNotHeldException();
 			}
+			int changes = jdbcTemplate.update(deleteQuery, lock.getName(),
+					lock.getValue());
+			return changes > 0;
 		}
-		int changes = jdbcTemplate.update(deleteQuery, lock.getName(), lock.getValue());
-		return changes > 0;
+		return false;
 	}
 
 	@Override
 	@Transactional(isolation = Isolation.REPEATABLE_READ)
 	public Lock refresh(String name, String value) throws LockNotHeldException {
 		Lock lock = getLock(name);
-		if (lock!=null) {
+		if (lock != null) {
 			if (!lock.getValue().equals(value)) {
 				throw new LockNotHeldException();
 			}
 			if (lock.isExpired()) {
 				throw new LockNotHeldException();
 			}
-		}
-		int changes = jdbcTemplate.update(refreshQuery, lock.getExpires(),
-				lock.getName(), lock.getValue());
-		if (changes > 0) {
-			return lock;
+
+			int changes = jdbcTemplate.update(refreshQuery, lock.getExpires(),
+					lock.getName(), lock.getValue());
+			if (changes > 0) {
+				return lock;
+			}
 		}
 		throw new LockNotHeldException();
 	}

src/main/java/locksdemo/Lock.java

@@ -22,6 +22,7 @@
 
 /**
  * A value object representing a named lock, with a globally unique value and an expiry.
+ *
  * @author Dave Syer
  *
  */
@@ -33,16 +34,18 @@ public class Lock implements Comparable<Lock> {
 	 * The name of the lock.
 	 */
 	private final String name;
+
 	/**
 	 * The value of the lock (globally unique, or at least different for locks with the
 	 * same name and different expiry).
 	 */
 	private final String value;
+
 	/**
 	 * The expiry of the lock expressed as a point in time.
 	 */
 	private final Date expires;
-	
+
 	public boolean isExpired() {
 		return expires.before(new Date());
 	}

src/main/java/locksdemo/LockService.java

@@ -24,15 +24,14 @@
  * holder to prove that he holds the lock. The value is thus unique per lock and per
  * expiry period (i.e. 2 locks held at different times with the same name will have
  * different values)..
- * 
+ *
  * @author Dave Syer
  *
  */
 public interface LockService {
 
 	/**
 	 * Iterate the existing locks.
-	 * 
 	 * @return an iterable of all locks
 	 */
 	Iterable<Lock> findAll();
@@ -42,7 +41,6 @@ public interface LockService {
 	 * hold the lock with this name at any given time. Locks expire and can also be
 	 * released by the owner, so after either of those events the lock can be acquired by
 	 * the same or a different process.
-	 * 
 	 * @param name the name identifying the lock
 	 * @return a Lock containing a value that can be used to release or refresh the lock
 	 * @throws LockExistsException
@@ -52,7 +50,6 @@ public interface LockService {
 	/**
 	 * Release a lock before it expires. Only the holder of a lock can release it, and the
 	 * holder must have the correct unique value to prove that he holds it.
-	 * 
 	 * @param name the name of the lock
 	 * @param value the value of the lock (which has to match the value when it was
 	 * acquired)
@@ -66,7 +63,6 @@ public interface LockService {
 	 * hold the lock there will be an exception, but the implementation may not be able to
 	 * tell if it was because he formerly held the lock and it expired, or if it simply
 	 * was never held.
-	 * 
 	 * @param name the name of the lock
 	 * @param value the value of the lock (which has to match the value when it was
 	 * acquired)

src/main/java/locksdemo/LocksApplication.java

@@ -20,42 +20,49 @@ public class LocksApplication extends WebMvcConfigurerAdapter {
 	public static void main(String[] args) {
 		SpringApplication.run(LocksApplication.class, args);
 	}
-	
+
 	@Bean
 	public LocksController locksController(LockService lockService) {
 		return new LocksController(lockService);
 	}
-	
+
 	@ConditionalOnClass(RedisConnectionFactory.class)
 	@ConditionalOnBean(RedisConnectionFactory.class)
 	@Configuration
 	protected static class RedisLockServiceConfiguration {
+
 		@Bean
 		@ConditionalOnMissingBean(LockService.class)
 		public RedisLockService lockService(RedisConnectionFactory connectionFactory) {
 			return new RedisLockService(connectionFactory);
 		}
+
 	}
 
 	@ConditionalOnClass(RedisConnectionFactory.class)
 	@ConditionalOnMissingBean(RedisConnectionFactory.class)
 	@Configuration
 	protected static class FallbackSimpleLockServiceConfiguration {
+
 		@Bean
 		@ConditionalOnMissingBean(LockService.class)
 		public SimpleLockService lockService() {
 			return new SimpleLockService();
 		}
+
 	}
 
-	@ConditionalOnMissingClass(name="org.springframework.data.redis.connection.RedisConnectionFactory")
+	@ConditionalOnMissingClass(
+			name = "org.springframework.data.redis.connection.RedisConnectionFactory")
 	@Configuration
 	protected static class SimpleLockServiceConfiguration {
+
 		@Bean
 		@ConditionalOnMissingBean(LockService.class)
 		public SimpleLockService lockService() {
 			return new SimpleLockService();
 		}
+
 	}
 
 }

src/main/java/locksdemo/LocksController.java

@@ -33,63 +33,63 @@
 
 /**
  * @author Dave Syer
- *
  */
 @RestController
 @RequestMapping("/")
-@RequiredArgsConstructor(onConstructor=@_(@Autowired))
+@RequiredArgsConstructor(onConstructor = @_(@Autowired))
 public class LocksController {
-	
+
 	private final LockService service;
 
-	@RequestMapping(method=RequestMethod.GET)
+	@RequestMapping(method = RequestMethod.GET)
 	public Iterable<Lock> locks() {
 		return service.findAll();
 	}
 
-	@RequestMapping(value="{name}", method=RequestMethod.POST)
+	@RequestMapping(value = "{name}", method = RequestMethod.POST)
 	public Lock create(@PathVariable String name) {
 		return service.create(name);
 	}
 
-	@RequestMapping(value="{name}/{value}", method=RequestMethod.DELETE)
-	public Map<String, Object> release(@PathVariable String name, @PathVariable String value) {
+	@RequestMapping(value = "{name}/{value}", method = RequestMethod.DELETE)
+	public Map<String, Object> release(@PathVariable String name,
+			@PathVariable String value) {
 		if (!service.release(name, value)) {
 			throw new NoSuchLockException();
 		}
 		return Collections.singletonMap("status", (Object) "OK");
 	}
 
-	@RequestMapping(value="{name}/{value}", method=RequestMethod.PUT)
+	@RequestMapping(value = "{name}/{value}", method = RequestMethod.PUT)
 	public Lock refresh(@PathVariable String name, @PathVariable String value) {
 		return service.refresh(name, value);
 	}
-	
+
 	@ExceptionHandler(LockExistsException.class)
 	@ResponseBody
 	public ResponseEntity<Map<String, Object>> lockExists() {
 		Map<String, Object> body = new HashMap<String, Object>();
 		body.put("status", "INVALID");
 		body.put("description", "Lock already exists");
-		return new ResponseEntity<Map<String, Object>>(body, HttpStatus.BAD_REQUEST);
+		return new ResponseEntity<>(body, HttpStatus.BAD_REQUEST);
 	}
 
 	@ExceptionHandler(NoSuchLockException.class)
 	@ResponseBody
 	public ResponseEntity<Map<String, Object>> noSuchLock() {
-		Map<String, Object> body = new HashMap<String, Object>();
+		Map<String, Object> body = new HashMap<>();
 		body.put("status", "INVALID");
 		body.put("description", "Lock not found");
-		return new ResponseEntity<Map<String, Object>>(body, HttpStatus.NOT_FOUND);
+		return new ResponseEntity<>(body, HttpStatus.NOT_FOUND);
 	}
 
 	@ExceptionHandler(LockNotHeldException.class)
 	@ResponseBody
 	public ResponseEntity<Map<String, Object>> lockNotHeld() {
-		Map<String, Object> body = new HashMap<String, Object>();
+		Map<String, Object> body = new HashMap<>();
 		body.put("status", "INVALID");
 		body.put("description", "Lock not held (values do not match)");
-		return new ResponseEntity<Map<String, Object>>(body, HttpStatus.NOT_FOUND);
+		return new ResponseEntity<>(body, HttpStatus.NOT_FOUND);
 	}
 
 }