Android / Java - 如何在单独的* .java文件中调用函数？

问题描述

我导入完整的包名/ java文件，如果我执行< classname>。< method> ，有时候我可以将它转到访问 - 其他时候我得到很多不能在非静态一堆谈话中使用静态。

I do an import of the full package name / java file, and if I do a <classname>.<method>, SOMETIMES I can get it to access - other times I get a lot of can't use a static in a non static bunch of talk.

我承认我是Java的新手，所以我需要做什么？先调用一个类实例，然后调用我的方法？我对此感到困惑，因为我想将所有'函数'放入一个FunctionsList.java文件中，并将所有主要的Activity（UI）放入MyActivity.java文件中。

I'll admit I'm new to Java, so what do I need to do? Call a class instance first, then call my methods? I'm rather confused by this, as I want to put all of my 'functions' into a FunctionsList.java file, and all of my main Activity (UI) into a MyActivity.java file.

例如：

<MyActivity.java>

import com.example.FunctionsList;

private class MyActivity extends Activity {
  FunctionsList.function();
}

9/10次我得到静态/非静态错误。

9/10 times I get that static/non-static error.

如果我将所有函数都放入MyActivity.java，我就没有问题！有人帮我解决了我认为是基本的Java新手问题吗？

If I put all of my functions into MyActivity.java, I have zero problems! Anyone help me on what I presume is a basic Java newbie issue?

推荐答案

这里有一个例子可以帮助你一点点帮助你。

Here's an example that will hopefully help you out a little.

public class MyFunctionClass {

   public String myFunction() {
      return "This is an instance function.";
   }

   public static String myStaticFunction() {
      return "This is a static function.";
   }

}

然后在你的活动中你有东西像这样。

Then in your activity you have something like this.

public class MyActivity extends Activity {

   @Override
   public void onCreate() {

      // If you want to call your static function, you do not
      // require an instance of a MyFunctionClass object.
      String myStaticString = MyFunctionClass.myStaticFunction();

      // If you want to call your instance function, then you need
      // to create a MyFunctionClass first.
      MyFunctionClass variableName = new MyFunctionClass();
      String myInstanceString = variableName.myFunction();
   }
}

正如Jon所说，你可能会节省一些钱如果你在潜水之前阅读面向对象的编程，会感到沮丧。在潜入之前，新程序员需要了解一些基本的东西。祝你好运！

As Jon mentioned, you'll probably save yourself some frustration if you read up on object-oriented programming before diving in. There are some basic things that a new programmer will need to understand before diving in. Good luck!

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