java - 反射。执行带参数的非静态方法

Question

我需要通过反射执行一些方法

执行方法

public void someMethod(int value1, int value2, String str, int value3)
{
    try
    {
        // some code
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
}

这是执行代码

public static void execute()
{
    try
    {
        String          className = "some.class";
        String          classPath = "some.pack.name" + ":" + "some.class";
        PathClassLoader loader    = new dalvik.system.PathClassLoader(classPath, ClassLoader.getSystemClassLoader());

        Class           clazz     = Class.forName(className, true, loader);
        Method          method    = clazz.getDeclaredMethod("someMethod", Integer.class, Integer.class, String.class, Integer.class); 
        Object          object    = clazz.newInstance();

        method.invoke(object, 1, 2, "str", 3);
    }
    catch (Throwable e) {e.printStackTrace();}
}

但是我收到错误

01-22 21:44:52.286: W/System.err(10877): java.lang.NoSuchMethodException: someMethod [class java.lang.Integer, class java.lang.Integer, class java.lang.String, class java.lang.Integer]
01-22 21:44:52.286: W/System.err(10877):    at java.lang.Class.getConstructorOrMethod(Class.java:472)
01-22 21:44:52.286: W/System.err(10877):    at java.lang.Class.getDeclaredMethod(Class.java:640)

我做错了什么？

Answer 1

类文字Integer.class 表示Integer 类，而不是int 原始数据类型。查找方法时，反射不会执行从 Integer 到 int 的拆箱转换。

使用Integer.TYPE表示 int 原始类型。

The Class instance representing the primitive type int.

Method method = clazz.getDeclaredMethod("someMethod", Integer.TYPE, Integer.TYPE, String.class, Integer.TYPE); 

您还可以使用类文字int.class，如 Section 15.8.2 of the JLS状态:

A class literal is an expression consisting of the name of a class, interface, array, or primitive type, or the pseudo-type void, followed by a '.' and the token class.

(粗体强调我的)