import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;

/**
 * {@link <a href=
 * "https://[Log in to view URL]"
 * target="_blank">Custom exception</a>}
 * 
 * @author itammb ( Italia Massimiliano Buscati )
 * @version JDK 1.15
 *
 */
class Main {
	/**
	 * @see Trace
	 * @see Exception
	 *
	 */
	public static class CustomException extends Trace {
		private static final long serialVersionUID = -69L;

		private final Exception EX;

		protected CustomException(Exception eX) {
			EX = eX;
		}

		public String print() {
			return this.print(EX);
		}
	}

	public static abstract class Trace extends Throwable {
		private static final long serialVersionUID = -69L;

		/**
		 * @see Throwable
		 * 
		 * {@link PrintWriter} {@link StringWriter}
		 *
		 */
		protected String print(Throwable ex) {
			PrintWriter pw = null;
			StringWriter sw = null;

			try {
				sw = new StringWriter();
				pw = new PrintWriter(sw);
				ex.printStackTrace(pw);

				return sw.toString();
			} finally {
				closeWriter(pw);
				closeWriter(sw);
			}
		}

		/**
		 * @see Writer
		 *
		 */
		private void closeWriter(Writer writer) {
			try {
				if (writer != null)
					writer.close();
			} catch (IOException IOex) {
				IOex.printStackTrace();
			}
		}
	}

	public static void exit() throws CustomException {
		try {
			int[] array = new int[4];

			System.out.println(array[4]);
		} catch (ArrayIndexOutOfBoundsException ex) {
			throw new CustomException(ex);
		}
	}

	public static void main(String args[]) throws Exception {
		// Unit test - lancio di un'eccezione manuale 
		try {
			exit();
		} catch (CustomException ex) {
			System.out.println(ex.print());
		}

		System.out.println("qui prosegue il flusso dopo un CustomException gestito");
	}
}