find method: All args must be supplied, if any args are null then this method returns null. - Java Reflection

Java examples for Reflection:Method Return

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Description

find method: All args must be supplied, if any args are null then this method returns null.

Demo Code


//package com.java2s;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

public class Main {
    /**//from  ww  w. j a va 2 s . co m
     * All args must be supplied, if any args are null then this method returns null.
     * 
     * @param type
     * @param methodName
     * @param parameterTypes
     * @param resultType
     * @return
     */
    public static Method findMethod(Class<?> type, String methodName,
            Class<?>[] parameterTypes, Class<?> resultType) {
        if (type == null || methodName == null || parameterTypes == null
                || resultType == null)
            return null;

        List<Method> compatibleMethods = new ArrayList<Method>();

        for (Method method : type.getMethods()) {
            if (!methodName.equals(method.getName()))
                continue;
            if (!method.getReturnType().isAssignableFrom(resultType))
                continue;

            Class<?>[] methodParameterTypes = method.getParameterTypes();
            if (methodParameterTypes.length != parameterTypes.length)
                continue;

            boolean compatibleParameters = true;
            for (int parameterIndex = 0; parameterIndex < parameterTypes.length
                    && compatibleParameters; ++parameterIndex)
                compatibleParameters |= methodParameterTypes[parameterIndex]
                        .isAssignableFrom(parameterTypes[parameterIndex]);
            if (!compatibleParameters)
                continue;

            compatibleMethods.add(method);
        }

        return compatibleMethods.size() > 0 ? compatibleMethods.get(0)
                : null;
    }
}

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