Returns a constructor with single argument. - Java Reflection

Java examples for Reflection:Constructor

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Description

Returns a constructor with single argument.

Demo Code

/*//  w w w. j a va 2s  .c  o m
 * Copyright (c) 2007-2016 AREasy Runtime
 *
 * This library, AREasy Runtime and API for BMC Remedy AR System, is free software ("Licensed Software");
 * you can redistribute it and/or modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either version 2.1 of the License,
 * or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * including but not limited to, the implied warranty of MERCHANTABILITY, NONINFRINGEMENT,
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 */
//package com.java2s;
import java.lang.reflect.Constructor;

import java.lang.reflect.Modifier;

public class Main {
    /**
     * Returns a constructor with single argument.
     *
     * @param klass the class to be constructed
     * @return null if matching accessible constructor can not be found.
     * @see Class#getConstructor
     * @see #getAccessibleConstructor(java.lang.reflect.Constructor)
     */
    public static Constructor getAccessibleConstructor(Class klass,
            Class parameterType) {

        Class[] parameterTypes = { parameterType };
        return getAccessibleConstructor(klass, parameterTypes);

    }

    /**
     * Returns a constructor given a class and signature.
     *
     * @param klass          the class to be constructed
     * @param parameterTypes the parameter array
     * @return null if matching accessible constructor can not be found
     * @see Class#getConstructor
     * @see #getAccessibleConstructor(java.lang.reflect.Constructor)
     */
    public static Constructor getAccessibleConstructor(Class klass,
            Class[] parameterTypes) {

        try {
            return getAccessibleConstructor(klass
                    .getConstructor(parameterTypes));
        } catch (NoSuchMethodException e) {
            return (null);
        }

    }

    /**
     * Returns accessible version of the given constructor.
     *
     * @param ctor prototype constructor object.
     * @return <code>null</code> if accessible constructor can not be found.
     * @see java.lang.SecurityManager
     */
    public static Constructor getAccessibleConstructor(Constructor ctor) {

        // Make sure we have a method to check
        if (ctor == null) {
            return (null);
        }

        // If the requested method is not public we cannot call it
        if (!Modifier.isPublic(ctor.getModifiers())) {
            return (null);
        }

        // If the declaring class is public, we are done
        Class clazz = ctor.getDeclaringClass();
        if (Modifier.isPublic(clazz.getModifiers())) {
            return (ctor);
        }

        // what else can we do?
        return null;

    }
}

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