Java 反射，getMethod()
我正在研究 Java 反射的基础知识并观察类方法的信息。我需要获取一个与 getMethod() 函数所描述的规范相匹配的方法。然而，当我这样做时，我得到一个 NoSuchMethodException，我希望你能告诉我为什么我的实现不正确。
static void methodInfo2(String className) throws ClassNotFoundException,
NoSuchMethodException{
Class cls = null;
try{
cls = Class.forName(className);
} catch(ClassNotFoundException e){
e.printStackTrace();
}
System.out.println("Cls: "+cls);
Method method1 = cls.getMethod("test", null);
System.out.println("method1: "+method1);
}
EDIT1：当我打印出“Cls：”+cls时，输出是“Cls：class a8.myclass2”。为什么它附加类部分？ （a8是正确的，所以不用担心） /EDIT1
这是我用来从我的主函数中读取类的函数，然后我想要带有参数“test”和null的getMethod()，其中“test”是方法的名称，null 表示该方法没有参数。我正在阅读的类称为 myclass2，如下所示：
package a8;
public class myclass2 {
void test(){
//"takes no parameters"
//"returns bool"
//"name starts with test"
//return true;
}
}
正如您所看到的，该方法确实存在于该类中。如果您能指出我的错误，我将不胜感激。
I'm working with the basics of Java reflection and observing information on methods of classes. I need to get a method that matches specifications as described by the getMethod() function. However, when I do this I get a NoSuchMethodException, and I was hoping you could tell me why my implementation is incorrect.
static void methodInfo2(String className) throws ClassNotFoundException,
NoSuchMethodException{
Class cls = null;
try{
cls = Class.forName(className);
} catch(ClassNotFoundException e){
e.printStackTrace();
}
System.out.println("Cls: "+cls);
Method method1 = cls.getMethod("test", null);
System.out.println("method1: "+method1);
}
EDIT1:When I print out "Cls: "+cls, the output is "Cls: class a8.myclass2". Why does it append the class part? (the a8 is correct, so don't worry about that) /EDIT1
This is the function I use to read in a class from my main function, and then I want to getMethod() with the parameters "test" and null, where "test" is the name of the method and null means the method has no parameters. The class I am reading in is called myclass2 which is here:
package a8;
public class myclass2 {
void test(){
//"takes no parameters"
//"returns bool"
//"name starts with test"
//return true;
}
}
As you can see, the method does infact exist in the class. If you could point out my mistake, I would really appreciate it.
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公开您的测试方法。我相信 Class.getMethod() 仅限于公共方法。
Make your test method public. I believe Class.getMethod() is limited to public methods.
如果您没有发布确切的异常和输出，则很难判断，但我怀疑这是因为这些类位于两个单独的包中，并且由于方法的默认修饰符只是受保护的，所以它会失败。
使用
getDeclaredMethod()获取通常不可见的方法。Without you posting the exact exception and your output, its hard to tell, but I suspect it is because the classes are in two separate packages, and since the default modifiers for a method are just
protectedit fails.Use
getDeclaredMethod()to get a method that isn't normally visible.