Utilities

@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.LOCAL_VARIABLE})
@Retention(RetentionPolicy.SOURCE)
public @interface NonNull {
}

@Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
@Retention(RetentionPolicy.SOURCE)
public @interface SneakyThrows {
    Class<? extends Throwable>[] value() default java.lang.Throwable.class;
}

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.SOURCE)
public @interface Synchronized {
    String value() default "";
}

@Target(ElementType.LOCAL_VARIABLE)
@Retention(RetentionPolicy.SOURCE)
public @interface Cleanup {
    String value() default "close";
}

/**
 * Guards all statements in an annotation method with a Lock.
 * 
 * For non-static methods, a field named $lock is used, and for static methods,
 * $LOCK is used. These will be generated if needed and if they aren't already present.
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.SOURCE)
public @interface Locked {
    /**
     * Optional: specify the name of a different field to lock on. It is a compile time error if this field
     * doesn't already exist (the fields are automatically generated only if you don't specify a specific name).
     *
     * @return Name of the field to lock on (blank = generate one).
     */
    String value() default "";
    
    /**
     * Locks using a ReadWriteLock#readLock().
     */
    @Target(ElementType.METHOD)
    @Retention(RetentionPolicy.SOURCE)
    public @interface Read {
        String value() default "";
    }
    
    /**
     * Locks using a ReadWriteLock#writeLock().
     */
    @Target(ElementType.METHOD)
    @Retention(RetentionPolicy.SOURCE)
    public @interface Write {
        String value() default "";
    }
}

import lombok.*;
import java.nio.file.*;
import java.io.*;

public class FileProcessor {
    @SneakyThrows
    public String readFile(String filename) {
        return Files.readString(Paths.get(filename));
    }

    @Synchronized
    public void processData(@NonNull String data) {
        // Thread-safe processing using synchronized block
    }
    
    @Locked
    public void updateCounter() {
        // Thread-safe using java.util.concurrent.locks.Lock
        counter++;
    }
    
    @Locked.Read
    public int readCounter() {
        // Thread-safe read using ReadWriteLock.readLock()
        return counter;
    }
    
    @Locked.Write  
    public void resetCounter() {
        // Thread-safe write using ReadWriteLock.writeLock()
        counter = 0;
    }

    @SneakyThrows
    public void processFile(String filename) {
        @Cleanup FileInputStream fis = new FileInputStream(filename);
        // File will be automatically closed
        // Process file content...
    }
}