Java Reflection Constructor Get getConstructorWithLeastParametersFromList( ArrayList constructorsFromType)

Description

get Constructor With Least Parameters From List

License

Apache License

Declaration

public static <T> Constructor getConstructorWithLeastParametersFromList(
            ArrayList<Constructor> constructorsFromType) 

Method Source Code

//package com.java2s;
/**//from   w w w . j  a v  a 2 s .  co  m
 * Copyright 2013 Hunter Hegler
 * 
 * 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.
 * 
 */

import java.lang.reflect.Constructor;

import java.util.ArrayList;

public class Main {
    public static <T> Constructor getConstructorWithLeastParametersFromList(
            ArrayList<Constructor> constructorsFromType) {

        Constructor planBConstructor = Object.class
                .getDeclaredConstructors()[0];
        Constructor retVal;

        if (!constructorsFromType.isEmpty()) {

            //initially assume that first constructor is best
            int index = 0;
            retVal = constructorsFromType.get(index);
            index++;

            //look for constructor that does not throw exceptions
            while (retVal.getExceptionTypes().length > 0
                    && index < constructorsFromType.size()) {
                retVal = constructorsFromType.get(index);
                index++;
            }

            if (!(retVal.getExceptionTypes().length > 0)) {
                //Try to find constructor with less number of parameters
                for (int i = 1; i < constructorsFromType.size(); i++) {
                    Constructor next = constructorsFromType.get(i);
                    if (next.getParameterTypes().length < retVal
                            .getParameterTypes().length) {
                        retVal = next;

                    }
                }
            }

        } else {

            retVal = planBConstructor;
        }

        //        if (retVal.getParameterTypes().length == 1 && retVal.getParameterTypes()[0] == type) {
        //            retVal = ArrayList.class.getDeclaredConstructors()[0];
        //
        //        }

        return retVal;
    }
}

Related

1. getConstructorSignature(final Constructor constructor)
2. getConstructorSignatureWithLongTypeNames(Constructor init)
3. getConstructorSimpleName(Constructor constructor)
4. getConstructorsOfLength(final Class clazz, final int length)
5. getConstructorWithArgs(Class clazz, Object... args)
6. getConstructorWithNoParams(Class clazz)
7. getConstructorWithReflection(String className, Class... parameterTypes)