从活动中调用另一活动的方法 [英] Calling a method in another activity from an activity

问题描述

好了，所以第一关，我知道，你不能从另一个活动的活动，多数民众赞成调用一个方法。我只是试图找出解决这个问题的最好办法。我是新来的Andr​​oid编程，所以我道歉，如果这是明显的东西。

Ok so first off I know that you can't call a method from an Activity thats in another Activity. I'm just trying to figure out the best way around this. I'm new to android programming so I apologize if it is something obvious.

下面是我的code。这是方法，我试图打电话。这是我的记分卡的活动。

Here is my code. This is the method I am trying to call. It is in my ScoreCard activity.

public void numPlayerSetup(){
            {
                 int[] ids = {
                            R.id.TextView11, R.id.TextView12, R.id.TextView13
                        };

                        for(int i : ids) {
                            TextView tv = (TextView)findViewById(i);
                            tv.setVisibility(View.INVISIBLE);
                        }

                     }
                 }

下面是我如何想调用的方法。分数是记分卡类的一个对象。

Here is how I am trying to call the method. score is an object of the ScoreCard class.

public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3){
            int item = spinner.getSelectedItemPosition();


            if(item==1){
                Log.i("error","This Sucks");
                score.numPlayerSetup();

        }
        }

我试图把numPlayerSetup方法在不同的班级。这不会扩大活动，只包含了逻辑，但不延长活动我无法使用findViewById（）方法。

I tried to put the numPlayerSetup method in a different class. That would not extend Activity, just contain the logic, but I can't use the findViewById() method without extending activity.

我希望我的问题是清楚的。感谢您的帮助！

I hope my question is clear. Thanks for the help!

@ninjasense

@ninjasense

这是我如何调用它。

 public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3){
            int item = spinner.getSelectedItemPosition();
            ArrayList<TextView> myTextViewList = new ArrayList<TextView>();

            TextView tv1 = (TextView)findViewById(R.id.TextView14);
            myTextViewList.add(tv1);

            if(item==1){
                Log.i("error","This Sucks");
                Setup.numPlayerSetup(myTextViewList);

        }

那么这是类我打电话。

Then this is the class I am calling.

public class Setup {
    TextView tv;

    public static void numPlayerSetup(ArrayList<TextView> tvs){
                     for(TextView tv : tvs) {
                         Log.i("crash","This Sucks");
                                tv.setVisibility(View.INVISIBLE);  //this line is highlighted in the debugger as the line my error is coming from
                            }    
                 }
    }

它记录在logcat的消息，并给了我一个空指针异常。调试器说，电视值为null。这究竟是为什么我得到一个空指针异常？

It logs the message in the logcat and gives me a null pointer exception. The debugger says that the value for tv is null. Is this why I am getting a null pointer exception?

推荐答案

您可以只需打个Utitlity类（不活动）并传入你想改变Textviews。而当您需要它调用该方法。

You can just make a Utitlity class(not Activity) and pass in the Textviews you wish to change. and call that method whenever you need it.

public class Setup {

public static void numPlayerSetup(ArrayList<TextView> tvs){

                 for(TextView tv : tvs) {
                            tv.setVisibility(View.INVISIBLE);
                        }    
             }
}

然后你可以使用它像（以活动）：

Then you can use it like(in Activity):

ArrayList<TextView> myTextViewList = new ArrayList<TextView>();
TextView tv1 = (TextView)findViewById(R.id.tv1);
myTextViewList.add(tv1);


    Setup.numPlayerSetup(myTextViewList);

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