传入“任何”类类型转换为java方法 [英] Passing in "any" class type into a java method

问题描述

好吧，我有一个类：

public class ExampleClass() {
    public void exampleClassMethod(ArrayList<CustomClass> abcdefg> arrList) {
        ....
    }
    public void exampleClassMethod2(ArgumentToTakeInAnyCustomClass custClassArg) {
        ....
    }
}

现在我想能够将任何对象的任何数组列表传递给该类的方法。

Now I want to be able to pass in any array list of any objects into that method in that class.

假设我要传入的自定义类是CustomClass1，CustomClass2，CustomClass3。

Let's say my custom classes to pass in would be CustomClass1, CustomClass2, CustomClass3.

我如何设置该方法来接受我传入的任何ArrayList？此外，让我说，我只是想传递一个类本身，如在第二个示例方法，我该怎么做？

How would I set up that method to accept any ArrayList that I pass in? Also, lets say I just wanted to pass in one of those classes themselves, as in the second example method, how would I do that?

谢谢。

public void testerMethodInitiater() {
    CustomClass1 abc = new CustomClass1();
    tester((Object) abc);
}
public static void tester(Object abc) {
    //do stuff
    System.out.println(abc);
    if(abc instanceof CustomClass1) {
        System.out.println("This is a CustomClass1");
    }
    (I need to tell the program to create a new CustomClass1 here if it's a CustomClass1) tester;// = new Object<Universalvars.getClassInUse()>;

}  

$ b ，但我不知道如何做一个新的CustomClass1在这个时候，除非我做了一个条件语句命名可能发生的所有可能性，我试图避免。

Code above prints out that the object is an instance of CustomClass1, but I'm not sure how to make a new CustomClass1 at this time unless I did a conditional statement naming all possibilities that could take place which I'm trying to avoid.

推荐答案

任何 ArrayList ：

public void example( ArrayList<?> arr ) { ...

任何类型的 CustomClass ：

public void example( ArrayList< ? extends CustomClass> arr ) { ...

您可以使用反射创建任何类型的新对象：

For the second half of your question, you can create a new object of any type with reflection:

public void tester( Object obj ) {
  Object obj2 = obj.getClass().newInstance();
}

这需要 Object 有一个零参数构造函数。我不知道你为什么要这样做。你可能想要实现 clone（），或者你可能想更多地考虑你的真正目标。通常在 CustomClass 中添加多态方法来解决这些我有什么类问题。

This requires that the class of Object has a zero-argument constructor. I don't know why you'd want to do this however. You might want to implement clone() instead, or you might want to think a little more about your real goal at the end of all this is. Usually adding a polymorphic method to CustomClass solves these "what class do I have" type questions.

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