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Generic Evolver utility classes

There is a newer version: 3.5.0

package fi.evolver.utils.arg;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;


public class EnumArg> extends Arg {

	private final Class type;
	private final Method parseMethod;
	private final List options;


	public EnumArg(Class type, String name) {
		this(type, name, true, null);
	}

	public EnumArg(Class type, String name, T defaultValue) {
		this(type, name, false, defaultValue);
	}


	private EnumArg(Class type, String name, boolean required, T defaultValue) {
		super(type, name, required, defaultValue);
		this.type = type;
		this.options = listOptions(type);
		this.parseMethod = getValueOfMethod(type);
	}


	@Override
	public String getType() {
		return String.class.getName();
	}


	public List getOptions() {
		return options;
	}


	@Override
	protected T convert(InputStream in) throws IOException {
		String value = readUtf8Value(in);
		try {
			return type.cast(parseMethod.invoke(null, value));
		}
		catch (IllegalArgumentException e) {
			throw new IllegalArgumentException(String.format("Invalid value '%s' for enum %s", value, type.getSimpleName()));
		}
		catch (IllegalAccessException | InvocationTargetException e) {
			throw new IllegalArgumentException("Could not get valueOf method for enum class " + type.getSimpleName(), e);
		}
	}


	private List listOptions(Class type) {
		try {
			return Arrays.stream((Enum[])type.getMethod("values").invoke(null))
					.map(Enum::name)
					.collect(Collectors.toList());
		}
		catch (NoSuchMethodException | SecurityException | IllegalAccessException | InvocationTargetException e) {
			throw new IllegalArgumentException("Could not list possible values for enum class " + type.getSimpleName(), e);
		}
	}


	private Method getValueOfMethod(Class type) {
		try {
			return type.getMethod("valueOf", String.class);
		}
		catch (NoSuchMethodException | SecurityException e) {
			throw new IllegalArgumentException("Could not get valueOf method for enum class " + type.getSimpleName(), e);
		}
	}

}