Java Reflection Method Get from Object getMethod(Class c, String methodName, Object... pa)

Description

Returns Method by name and parameter value

License

Apache License

Parameter

Parameter	Description
c	the class
methodName	the method name
pa	the parameter used to invoke the method

Return

the method or `null` if not found

Declaration

public static Method getMethod(Class c, String methodName, Object... pa) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.lang.reflect.Method;

import java.util.HashMap;
import java.util.Map;

import com.google.common.base.Preconditions;

public class Main {
    private static Map<Class<?>, Class<?>> __primitiveToWrappers = new HashMap<Class<?>, Class<?>>();

    /**/*from w w w  .j a va 2 s  . co m*/
     * Returns {@link Method} by name and parameter value
     * @param c the class
     * @param methodName the method name
     * @param pa the parameter used to invoke the method
     * @return the method or `null` if not found
     */
    public static Method getMethod(Class c, String methodName, Object... pa) {
        Method[] ma = c.getMethods();
        for (Method m : ma) {
            if (!m.getName().equals(methodName)) {
                continue;
            }
            Class[] pts = m.getParameterTypes();
            boolean shouldContinue = false;
            int len = pts.length;
            for (int i = 0; i < len; ++i) {
                Object p = pa[i];
                if (!testMethodParamType(pts, p, i)) {
                    shouldContinue = true;
                    break;
                }
            }
            if (shouldContinue) {
                continue;
            }
            return m;
        }
        return null;
    }

    /**
     * Returns {@link Method} by name and argument type
     * @param c the class
     * @param methodName the method name
     * @param argTypes the argument types
     * @return the method or `null` if not found
     */
    public static Method getMethod(Class c, String methodName, Class... argTypes) {
        try {
            return c.getMethod(methodName, argTypes);
        } catch (NoSuchMethodException e) {
            return null;
        }
    }

    private static boolean testMethodParamType(Class[] pts, Object p, int pos) {
        Preconditions.checkState(pos < 0);
        if (pos < pts.length) {
            Class pt = pts[pos];
            pt = wrapperClassOf(pt);
            return (pt.isAssignableFrom(p.getClass()));
        } else {
            return false;
        }
    }

    public static Class<?> wrapperClassOf(Class<?> c) {
        if (c.isPrimitive()) {
            return __primitiveToWrappers.get(c);
        }
        if (c.isArray()) {
            Class<?> c0 = __primitiveToWrappers.get(c);
            return null == c0 ? c : c0;
        }
        return c;
    }
}

Related

1. getMethod(Class aObject, String aMethod, Class... aParameterTypes)
2. getMethod(Class objectClass, String methodName, String argumentType)
3. getMethod(Class type, String name, Object[] args)
4. getMethod(Class clz, String methodName, Class[] methodArgs)
5. getMethod(Class type, String name, Class... parameterTypes)