com.arangodb.shaded.vertx.core.cli.converters.ConstructorBasedConverter Maven / Gradle / Ivy
/*
* Copyright (c) 2011-2019 Contributors to the Eclipse Foundation
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
* which is available at https://www.apache.org/licenses/LICENSE-2.0.
*
* SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
*/
package com.arangodb.shaded.vertx.core.cli.converters;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
/**
* This 'default' converter tries to create objects using a constructor taking a single String argument.
* Be aware that implementation must also handle the case where the input is {@literal null}.
*
* @author Clement Escoffier
*/
public final class ConstructorBasedConverter implements Converter {
private final Constructor constructor;
private ConstructorBasedConverter(Constructor constructor) {
this.constructor = constructor;
}
/**
* Checks whether the given class can be used by the {@link ConstructorBasedConverter} (i.e. has a constructor
* taking a single String as argument). If so, creates a new instance of converter for this type.
*
* @param clazz the class
* @return a {@link ConstructorBasedConverter} if the given class is eligible,
* {@literal null} otherwise.
*/
public static ConstructorBasedConverter getIfEligible(Class clazz) {
try {
final Constructor constructor = clazz.getConstructor(String.class);
if (!constructor.isAccessible()) {
constructor.setAccessible(true);
}
return new ConstructorBasedConverter<>(constructor);
} catch (NoSuchMethodException e) {
// The class does not have the right constructor, return null.
return null;
}
}
/**
* Converts the given input to an object by using the constructor approach. Notice that the constructor must
* expect receiving a {@literal null} value.
*
* @param input the input, can be {@literal null}
* @return the instance of T
* @throws IllegalArgumentException if the instance of T cannot be created from the input.
*/
@Override
public T fromString(String input) throws IllegalArgumentException {
try {
return constructor.newInstance(input);
} catch (InstantiationException | IllegalAccessException | InvocationTargetException e) {
if (e.getCause() != null) {
throw new IllegalArgumentException(e.getCause());
} else {
throw new IllegalArgumentException(e);
}
}
}
}