Utils.java

/*
 * Copyright 2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ratpack.retrofit.internal;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.WildcardType;
import java.util.Arrays;

public abstract class Utils {

  public static Type getSingleParameterUpperBound(ParameterizedType type) {
    Type[] types = type.getActualTypeArguments();
    if (types.length != 1) {
      throw new IllegalArgumentException(
        "Expected one type argument but got: " + Arrays.toString(types));
    }
    Type paramType = types[0];
    if (paramType instanceof WildcardType) {
      return ((WildcardType) paramType).getUpperBounds()[0];
    }
    return paramType;
  }
}