The below code shows hot to read the list of resources(files) from a classpath folder and subfolder.

Below is the example code

import java.io.*;
import java.net.URL;
import java.nio.file.Files;
import java.util.*;

public class ReadResourceFiles {

    public static void main(String[] args) throws IOException {
        List resourceFolderFiles = getResourceFolderFiles("static");
        resourceFolderFiles.stream().filter(f -> f.endsWith(".json")).forEach(System.out::println);
    }

    static List getResourceFolderFiles(String folder) {
        ClassLoader loader = Thread.currentThread().getContextClassLoader();
        URL url = loader.getResource(folder);
        String path = url.getPath();
        File file = new File(path);
        List files = new ArrayList<>();
        if(file.isDirectory()){
            try {
                Files.walk(file.toPath()).filter(Files::isRegularFile)
                        .filter(f-> f.toFile().getName().toLowerCase().endsWith(".json"))
                        .forEach(f -> files.add(f.toFile().getPath()));
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }else if(file.getName().toLowerCase().endsWith(".json")){
            files.add(file.getPath());
        }
        return files;
    }
}

Log Forging

private void printLog(String amount) {
logger.info("Amount credited in account Rs. {}" + amount);
}

    public String encode(String message) {
    message = message.replace( '\n' ,  '_' ).replace( '\r' , '_' )
      .replace( '\t' , '_' );
    message = ESAPI.encoder().encodeForHTML( message );
    return message;
}

 The ExecutorService interface, executes tasks in parallel in background and represents an asynchronous execution mechanism. The ExecutorService create and maintain the reusable thread pool.

How to create ExecutorService?

1. submit(Runnable)
2. submit(Callable)
3. execute(Runnable)
4. invokeAny(...)
5. invokeAll(...)

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class HTMLUnitMultipleThreads {

	public static void main(String[] args) {

		int threadSize = 5;
		ExecutorService executor = Executors.newFixedThreadPool(threadSize);
		for (int i = 0; i < threadSize; i++) {
			executor.submit(new MultiThreadingService());
		}
	}
}

public class MultiThreadingService implements Runnable {

	@Override
	public void run() {
		for (int i = 0; i < 10; i++) {
			System.out.println("Thread Name = " + Thread.currentThread().getName());
		}

	}

}