获取类并调用其主要功能的方法 [英] method that gets a class and calls its main function

问题描述

我想编写一个获取类和字符串数组的方法，并使用给定的数组调用类的主方法.

类似这样的东西:

 公共静态无效ExecuteMain(DefaultClass cls，String [] args){cls.main(args);} 

问题是，我想用几个类来做，而不能将确切的类作为类型传递.我也不能让所有其他类都实现默认接口或类，因为它应该用作具有相同类名的同学的测试器.

有什么办法可以解决这些限制吗?

解决方案

以下是您应如何定义方法的方法:

  public static void executeMain(Class<?> cls，Object [] args){尝试 {Object [] param = {args};方法method = cls.getDeclaredMethod("main"，args.getClass());method.invoke(cls，param);} catch(NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException|InvocationTargetException e){e.printStackTrace();}} 

演示

Assignment1.java:

  import java.util.Arrays;公共类Assignment1 {公共静态void main(String [] args){if(args == null){System.out.println(欢迎来到分配1")；} 别的 {System.out.println("Assignment1中main的参数:"+ Arrays.toString(args)))；}}} 

Assignment2.java

  import java.util.Arrays;公共类Assignment2 {公共静态void main(String [] args){if(args == null){System.out.println(欢迎来到分配2")；} 别的 {System.out.println("Assignment2中main的参数:"+ Arrays.toString(args)))；}}} 

测试类别:

  import java.lang.reflect.InvocationTargetException;导入java.lang.reflect.Method;公共班级主要{公共静态void main(String [] args){Assignment1.main(null);Assignment1.main(new String [] {"Hello"，"World"});Assignment2.main(null);Assignment2.main(new String [] {"Hello"，"World"});executeMain(Assignment1.class，new String [] {"Good"，"Morning"});executeMain(Assignment2.class，new String [] {"Good"，"Morning"});}公共静态void executeMain(Class<?> cls，Object [] args){尝试 {Object [] param = {args};方法method = cls.getDeclaredMethod("main"，args.getClass());method.invoke(cls，param);} catch(NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException|InvocationTargetException e){e.printStackTrace();}}} 

输出:

 欢迎来到Assignment1作业1中的main参数:[Hello，World]欢迎来到Assignment2作业2中main的参数:[Hello，World]作业1中主要的参数:[早上好]作业2中main的参数:[Good，Morning] 

选中此，以了解有关Java Reflection API的更多信息./p>

I want to write a method that gets a class and an Array of strings and call the main method of the class with the array given.

Something like this:

public static void ExecuteMain(DefaultClass cls, String[] args){
    cls.main(args);
}     

The problem is, I want to do it with several classes, and can't pass the exact class as the type. I also can't have all of the other classes implement a default interface or class because it should be used as a tester for my classmates with the same class names.

Is there any way to do it with those restrictions?

解决方案

Given below is how you should define the method:

public static void executeMain(Class<?> cls, Object[] args) {
    try {
        Object[] param = { args };
        Method method = cls.getDeclaredMethod("main", args.getClass());
        method.invoke(cls, param);
    } catch (NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException
            | InvocationTargetException e) {
        e.printStackTrace();
    }
}

Demo

Assignment1.java:

import java.util.Arrays;

public class Assignment1 {
    public static void main(String[] args) {
        if (args == null) {
            System.out.println("Welcome to Assignment1");
        } else {
            System.out.println("Arguments to main in Assignment1: " + Arrays.toString(args));
        }
    }
}

Assignment2.java

import java.util.Arrays;

public class Assignment2 {
    public static void main(String[] args) {
        if (args == null) {
            System.out.println("Welcome to Assignment2");
        } else {
            System.out.println("Arguments to main in Assignment2: " + Arrays.toString(args));
        }
    }
}

Test class:

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
    public static void main(String[] args) {
        Assignment1.main(null);
        Assignment1.main(new String[] { "Hello", "World" });
        Assignment2.main(null);
        Assignment2.main(new String[] { "Hello", "World" });
        executeMain(Assignment1.class, new String[] { "Good", "Morning" });
        executeMain(Assignment2.class, new String[] { "Good", "Morning" });
    }

    public static void executeMain(Class<?> cls, Object[] args) {
        try {
            Object[] param = { args };
            Method method = cls.getDeclaredMethod("main", args.getClass());
            method.invoke(cls, param);
        } catch (NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException
                | InvocationTargetException e) {
            e.printStackTrace();
        }
    }
}

Output:

Welcome to Assignment1
Arguments to main in Assignment1: [Hello, World]
Welcome to Assignment2
Arguments to main in Assignment2: [Hello, World]
Arguments to main in Assignment1: [Good, Morning]
Arguments to main in Assignment2: [Good, Morning]

Check this to learn more about Java Reflection API.

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