ActiveClassWithReflection.java

package org.tksmaru.playgound;

import java.lang.reflect.Constructor;

public class ActiveClassWithReflection {


	private enum ErrorType {
		LESS_MONEY("less.money", UserException.class),
		NO_STOCK("no.stock", ShopException.class),
		SHOP_CLOSE("shop.close", ShopException.class);

		private String message;
		private Class<? extends Exception> ex;

		private ErrorType(String message, Class<? extends Exception> ex) {
			this.message = message;
			this.ex = ex;
		}
		String getMessage() {
			return message;
		}


		Exception getException() {
			Class<? extends Exception> clazz = this.ex;
			try {
				// 引数がmessageのコンストラクタからインスタンスを生成する
				Constructor<? extends Exception> constructor = clazz.getConstructor(String.class);
				return constructor.newInstance(this.message);
			} catch (Exception e) {
				return new Exception("Invokation error.", e);
			}
		}
	}

	public void throwExceptionByErrorType(ErrorType error) throws UserException, ShopException, Exception {
		throw error.getException();
	}

	public static void main(String [] args) {
		ActiveClassWithReflection2 test = new ActiveClassWithReflection2();
		try {
			test.throwExceptionByErrorType(ErrorType.LESS_MONEY);
		} catch (UserException e) {
			System.out.println("UserException:" + e.getLocalizedMessage());
		} catch (ShopException e) {
			System.out.println("ShopException:" + e.getLocalizedMessage());
		} catch (Exception e) {
			System.out.println("Exception:" + e.getLocalizedMessage());
		}

		try {
			test.throwExceptionByErrorType(ErrorType.NO_STOCK);
		} catch (UserException e) {
			System.out.println("UserException:" + e.getLocalizedMessage());
		} catch (ShopException e) {
			System.out.println("ShopException:" + e.getLocalizedMessage());
		} catch (Exception e) {
			System.out.println("Exception:" + e.getLocalizedMessage());
		}
	}

	static class ShopException extends Exception {

		public ShopException(String message) {
			super(message);
		}
	}

	static class UserException extends Exception {

		public UserException(String message) {
			super(message);
		}
	}

}