CODEWITHSUNDEEP
javaandroidandroid-activity
dodo
dodo

Reputation: 141

Java how to use activity methods in another class

For example I have an activity class. In this class I have some variables and I'd like to use them in another class. This is the code:

public class SearchView {
    private MenuActivity menuActivity;

    public SearchView() {
        menuActivity = new MenuActivity();
        menuActivity.searchButton = (ImageView) menuActivity.findViewById(R.id.searchButton);
    }
}

Last line gives me a NullPointerException. I know I need to initialize it but how can I initialize an activity?

Upvotes: 5

Views: 351

Answers (3)

Kanifnath Modak
Kanifnath Modak

Reputation: 172

public class SearchView {
    private MenuActivity menuActivity;

    public SearchView(Activity activityRef) {
        MenuActivity.searchButton = (ImageView) activityRef.findViewById(R.id.searchButton);
    }
}

And declare searchButton as public static in activity.

public class MenuActivity extends Activity {
    public static Button searchButton;

    @Override
    protected void onCreate() {
        SearchView searchView = new SearchView(this);
    }
}

Hope it will help you. let me know once you are done.

Upvotes: 1

Merlí Escarpenter Pérez
Merlí Escarpenter Pérez

Reputation: 2657

You have a different options...

First one:

Create a getter to get values from classes:

public MenuActivity getMenuActivityVar(){
    return this.MenuActivity;
}

From other activity using this method like this:

//Other activity or class
//Declare a new var as your class
SearchView sView = new SearchView();

MenuActivity nMenu = sView.getMenuActivityVar();

Second one:

In this case is a static method means that all static vars have a static value you don't need declare a new class from this one because is static.

public static class SearchView {{
    public static MenuActivity menuActivity;
    .
    .

}

With this change you can call this var using:

//This call it's do it from other activity
MyNewVar = SearchView.MenuActivity;

Third one:

public class SearchView {
    public MenuActivity menuActivity;
}

From the other activity when you create a class like this:

SearchView sView = new SearchView();
//In this moment your var are null.

After if you modify this var in your class from methods for example then you can get var using like this:

MenuActivity MyNewMenu = sView.menuActivity;

I think the best option is first, it's the best important part of classes getters and setters from classes. Tell me if I helped you and good programming!

Upvotes: 2

Shriram
Shriram

Reputation: 4421

If you want the value of the variable pass it to next activity using intents. if it is a static value make it in separate constant file and use it with the class name. If it is a view make use of the view again in the next activity.

Upvotes: 0

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