Can't call a method from outside of a java class

Question

I have a method name checkForUpdate() in UpdateActivity.java. It looks like this:

@NonNull
@SuppressWarnings("deprecation")
protected String checkForUpdate(int curVersionCode) {
  HttpClient httpclient = new DefaultHttpClient();
  ... 
}

I am trying to call it from anotherActivity. So I'm trying to use code like this:

private void callFromAnotherActivity() {
  UpdateActivity updateApp = new UpdateActivity();
  String result = updateApp.checkForUpdate(...);
}

so when I type updateApp. then a list of the methods of UpdateActivity.java appears but there is no checkForUpdate() method. Why?

First of all this is not proper way to use Activities. Both of your Activities are in same package? — Sagar, May 31 '18 at 02:05
Can u share more code that you have written in firstActivity? — TaQuangTu, May 31 '18 at 02:18
This will not work and really shouldn't because you DO NOT want create a new `UpdateActivity` Activity just to use a method that you wish to reuse. Methods like `checkForUpdate()` are worthy of their own class if they are to be reusable. — Barns, May 31 '18 at 02:25
Ok. I think it is a long process. The code is not fully mine too. I'd rather try to get help from local source. Thank you very much for your effort. — Fechang Fuchang, May 31 '18 at 03:03
looks like you are missing both Java and Android basics like `Java access modifiers` and `Android Activities`. Please pass through some basic training before you continue — Vladyslav Matviienko, May 31 '18 at 05:23

ישו אוהב אותך · Answer 1 · 2018-05-31T04:45:27.090

so when I type updateApp. then a list of the methods of UpdateActivity.java appears but there is no checkForUpdate() method. Why?

This is because your method is not public and probably you haven't import the UpdateActivity.

Please be noted that you can't create an Activity by calling the following:

UpdateActivity updateApp = new UpdateActivity();

You need to use something like this:

// context is your activity context.
Intent updateApp = new Intent(context, UpdateActivity.class);
context.startActivity(updateApp);

My suggestion:

You need to move the checkForUpdate method from UpdateActivity and make it as an util. So, other activity using the method won't be dependent and coupled with UpdateActivity. Localize the method to an utility class something like this:

public class UpdateUtil {

  ...

  @NonNull
  @SuppressWarnings("deprecation")
  public static String checkForUpdate(int curVersionCode) {

    HttpClient httpclient = new DefaultHttpClient();
    ... 

  }
}

and then use the method with:

UpdateUtil.checkForUpdate(1);

If you can't move the code (e.g, you don't have ownership of the code), you can do these things:

Make the checkForUpdate as static method
Use EventBus to tell the UpdateActivity to do the update.

Thanks. I am trying to follow your suggestion. if succeed, i will let you know. You're right, i'm lacking some basic concepts. — Fechang Fuchang, Jun 06 '18 at 04:23

score 0 · Answer 2 · answered May 31 '18 at 07:51

0

You should not create an instance of the activity class. It is wrong. Activity has ui and lifecycle and activity is started by startActivity(intent) Check here : call a method in another Activity

answered May 31 '18 at 07:51

Quang Doan

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Can't call a method from outside of a java class

2 Answers2