How to use widget defined in my fragment, in main activity without onClick

Question

I'm pretty new in android development and I have some questions about how fragments communicate with their main activity.

How can i use a widget defined in my fragment without the Onclick method, i want to do something like:

in my MainActivity

textview = (textview) findbyid(R.id.textview)

when the textview is defined in fragment.

i'm working on a project in rosjava that's why i have to get the widget i defined in my fragment in order to execute them as ros node.

Answer 1

You could declare Fragment member and instantiate it in the Activity.

// Fragment.java
...
public TextView textview;
...

void onCreateView(...) {
//inflating view
...
textview = view.findViewbyId(R.id.textview);
...

//Activity.java
private MyFragment fragment;

...

fragment = MyFragment.newInstance();
// now u could do like that

fragment.textview.setText("hello");

Or u can get ur fragment object using FragmentManager:

Fragment fragment = getFragmentManager().findFragmentById(R.id.fragment_container);
if (fragment instanceof MyFragment) {
    MyFragment myfragemnt = (MyFragment) fragment;
    fragment.textview.setText("hello");
}