从另一个班级返还双倍的最简单方法 [英] Easiest way to return double from another class

问题描述

我希望根据输入的双精度数从另一个类返回一个双精度数。
任何非常简单的项目结构示例的好的链接/示例，将不胜感激。
我在清单中缺少什么吗？
即
活动1

I wish to return a double from another class depending on input doubles. Any good links/examples to very simple project structure examples would be appreciated. Am I missing something in manifest. ie. activity 1

import com.example.app.utils.getRhumbLineBearingUtil;


double tbearing =             getRhumbLineBearing(alata,alona,alatb,alonb);

double recipbearing=getRhumbLineBearing(alatb, alonb, alata, alona);

活动2
import com.example.app.utils.getRhumbLineBearingUtil;

Activity 2 import com.example.app.utils.getRhumbLineBearingUtil;

 double lattocbearing = getRhumbLineBearing(lat,lon,alatc,alonc);

 double bcbearing=getRhumbLineBearing(alatb, alonb, alatc, alonc);

（我在许多具有15种不同收益的活动中进行了此操作，其中一些输入即gps点快速变化）

(I do this over many activities with 15 different returns with some inputs ie gps points changing rapidly)

Class
包com.example.app.utils;

Class package com.example.app.utils;

public class getRhumbLineBearingUtil
{


public double getRhumbLineBearing(double $lat1, double $lon1, double $lat2, double $lon2)
  {Yada=trueRhumb  ;
double Bearing=yada;
Return (bearing);
      }
}

我对bearb并没有兴趣

I am not interested in bearingTo which is the initial bearing hearing.

推荐答案

您应该首先学习一些Java编程，然后再学习android。你不能那样做。试试这个：

You should first learn a bit of Java programming and then move-up to android. You cannot do that that way. Try this:

Class GetRhumbLineBearingUtil {    

    public static double getRhumbLineBearing(double lat1, double lon1, double lat2, double lon2) {
        return lat1 + lon1;
    }
}

然后在另一个类中，在导入之后，无论要使用该方法，只需像这样调用它：

And then in another class, after import and whatever you wanna use that method for, just call it like this:

double lattocbearing = GetRhumbLineBearingUtil.getRhumbLineBearing(alatb, alonb, alata, alona);

此处有一些注意事项：可以通过ClassName.methodName

Some notes here: static methods can be accessed via ClassName.methodName

这是我从问题中了解的内容。现在，如果您想在活动之间交换数据，那就是另一回事了，您可以使用意图。

This was what i understood from the question. Now if you want to exchange data between activities, then that is another story, you can use intents.

一些注意事项：

• 类名以upperCase开头


• 类，方法和方法参数应具有正确的名称/含义，以使其更容易理解所包含的内容


• 变量名以小写开头


• Java中没有 $ variable 通过值传递


• 如果要返回存储在类 GetRhumbLineBearingUtil 中的变量中的某些值，则需要将该变量设置为静态很好。

• Class names start with upperCase
• Classes, methods and method arguments should have a proper name/meaning to make it easier to understand what is being done.
• Variable names start lowerCase
• There is no $variable in Java, everything is passed by value
• If you want to return some value stored in a variable in class GetRhumbLineBearingUtil you need to make that variables static as well.

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