使用非活动类，该类应能够处理调用活动的实例变量 [英] Working with a non-activity class, which should be able to handle the instance variable of the calling activity

问题描述

我有两个活动A和B，一个非活动类C.

I have two activities A and B, and a non activity class C.

要使用C的方法，我从当前正在运行的活动中创建C的实例c(例如A在前台，而A已创建C).

To use the methods of C, I create an instance c of C from the currently running activity (say A is in the foreground, and A has created C).

现在，我想使用c中活动A的实例变量.我该怎么办?

Now, I want to use the instance variables of activity A from c. What should I do?

我正在尝试将非活动C类用于多个活动.请帮我！我已经研究了很多，但是仍然找不到任何有用的东西. :(

I am trying to use the non activity C class for multiple activities. Please help me! I have researched it a lot, but still couldn't find anything useful about it. :(

这是示例代码:

ActivityOne.java:

ActivityOne.java:

package com.example.vaibhav.a21matchsticks;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class Example extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    }

// Now comes the method, I want to use in the non-activity java class.

public void buttonClick(View view) {
    EditText editText = (EditText) findViewById(R.id.editMe); //finds the view from the activity
    int i = Integer.parseInt(editText.getText().toString());

    //Below code changes the view state, if the condition is true

    if(i<4) { 
        findViewById(R.id.button).setEnabled(false);
    }

}

假定xml文件具有线性布局，该布局具有一个EditText视图(标识为"editMe")和一个按钮(标识为"button").这样的活动不止1个，每个活动至少具有上述两个视图(并且可能更多).

Assume the xml file to have a linear layout having one EditText view (with id 'editMe') and a Button (with id 'button'). There are more than 1 activities like this, each having at least the above two views (and may be more).

我的工作是创建一个非活动类C，以处理不同活动的条件语句并相应地更改各自的布局.

My job is to create a non activity class C, to handle the conditional statement for different activities and change the respective layout accordingly.

推荐答案

尽管C语言很模糊，但您的C类似乎是一个帮助器类.现在，由于您要访问C类中的实例变量(可能还有其他信息)，因此需要手动传递它们.根据传递的内容，可以在C类的构造函数中或通过C类本身的实例方法将其提供给C类.

Even though a but vague, your Class C seems to be a helper class. Now, since you want to access instance variables (and possibly other information) in your C class, you need to pass them manually. Depending on what you are passing, it can be provided to Class C either in its constructor or via instance methods of the Class C itself.

例如:基于问题的最后一个陈述，您可以通过以下方式将ViewGroup引用从您的活动传递给C类:

For eg: based on the last statement of your question you can pass a ViewGroup reference from your activity to Class C via something like this:

public void initLayout(ViewGroup parent) {

    // Hide/unhide/perform actions/etc based on current activity needs

}

类似地，您也可以将enum值传递给Class C，以区分您在Class C中的活动.对于Class C与活动的通信，您可以查看Java中的interface.希望这会有所帮助.

Similarly, you can also pass an enum value to Class C to differentiate between your activities in Class C. For a Class C to activity communication, you can look at interface in Java. Hope this helps.

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