Home » Android » android – Calling a Fragment method from a parent Activity

android – Calling a Fragment method from a parent Activity

Posted by: admin March 11, 2020 Leave a comment

Questions:

I see in the Android Fragments Dev Guide that an “activity can call methods in a fragment by acquiring a reference to the Fragment from FragmentManager, using findFragmentById() or findFragmentByTag().”

The example that follows shows how to get a fragment reference, but not how to call specific methods in the fragment.

Can anyone give an example of how to do this? I would like to call a specific method in a Fragment from the parent Activity. Thanks.

How to&Answers:

not get the question exactly as it is too simple :

ExampleFragment fragment = (ExampleFragment) getFragmentManager().findFragmentById(R.id.example_fragment);
fragment.<specific_function_name>(); 

Update:
For those who are using Kotlin

var fragment = supportFragmentManager.findFragmentById(R.id.frameLayoutCW) as WebViewFragment
fragment.callAboutUsActivity()

Answer:

If you are using “import android.app.Fragment;”
Then use either:

1)

ExampleFragment fragment = (ExampleFragment) getFragmentManager().findFragmentById(R.id.example_fragment); 
fragment.specific_function_name(); 

Where R.id.example_fragment is most likely the FrameLayout id inside your xml layout.
OR

2)

ExampleFragment fragment = (ExampleFragment) getFragmentManager().findFragmentByTag(“FragTagName”); 
fragment.specific_function_name(); 

Where FragTagName is the name u specified when u did:

TabHost mTabHost.newTabSpec(“FragTagName”)

If you are using “import android.support.v4.app.Fragment;”
Then use either:

1)

ExampleFragment fragment = (ExampleFragment) getSupportFragmentManager().findFragmentById(R.id.example_fragment); 
fragment.specific_function_name(); 

OR

2)

ExampleFragment fragment = (ExampleFragment) getSupportFragmentManager().findFragmentByTag(“FragTagName”); 
fragment.specific_function_name(); 

Answer:

If you’re using a support library, you’ll want to do something like this:

FragmentManager manager = getSupportFragmentManager();
Fragment fragment = manager.findFragmentById(R.id.my_fragment);
fragment.myMethod();

Answer:

  1. If you’re not using a support library Fragment, then do the following:

((FragmentName) getFragmentManager().findFragmentById(R.id.fragment_id)).methodName();

2. If you’re using a support library Fragment, then do the following:

((FragmentName) getSupportFragmentManager().findFragmentById(R.id.fragment_id)).methodName();

Answer:

I think the best is to check if fragment is added before calling method in fragment. Do something like this to avoid null exception.

ExampleFragment fragment = (ExampleFragment) getFragmentManager().findFragmentById(R.id.example_fragment);
if(fragment.isAdded()){
  fragment.<specific_function_name>(); 
}

Answer:

From fragment to activty:

((YourActivityClassName)getActivity()).yourPublicMethod();

From activity to fragment:

FragmentManager fm = getSupportFragmentManager();

//if you added fragment via layout xml
YourFragmentClass fragment = 
(YourFragmentClass)fm.findFragmentById(R.id.your_fragment_id);
fragment.yourPublicMethod();

If you added fragment via code and used a tag string when you added your fragment, use findFragmentByTag instead:

YourFragmentClass fragment = (YourFragmentClass)fm.findFragmentByTag("yourTag");

Answer:

First you create method in your fragment like

public void name()
{


}

in your activity you add this

add onCreate() method

myfragment fragment=new myfragment()

finally call the method where you want to call add this

fragment.method_name();

try this code

Answer:

FragmentManager fm = getFragmentManager(); 
MainFragment frag = (MainFragment)fm.findFragmentById(R.id.main_fragment); 
frag.<specific_function_name>(); 

Answer:

I don’t know about Java, but in C# (Xamarin.Android) there is no need to look up the fragment everytime you need to call the method, see below:

public class BrandActivity : Activity
{
    MyFragment myFragment;

    protected override void OnCreate(Bundle bundle)
    {       
        // ...
        myFragment = new MyFragment();      
        // ...
    }

    void someMethod()
    {
        myFragment.MyPublicMethod();
    }
}

public class MyFragment : Android.Support.V4.App.Fragment
{
    public override void OnCreate(Bundle bundle)
    {
        // ...
    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle bundle)
    {
        // ...
    }

    public void MyPublicMethod()
    {
        // ...
    }   
}

I think in Java you can do the same.

Answer:

you also call fragment method using interface like

first you create interface

public interface InterfaceName {
    void methodName();
}

after creating interface you implement interface in your fragment

MyFragment extends Fragment implements InterfaceName {
    @overide
    void methodName() {

    }
}

and you create the reference of interface in your activity

class Activityname extends AppCompatActivity {
    Button click;
    MyFragment fragment;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity);

        click = findViewById(R.id.button);

        fragment = new MyFragment();

        click.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
               fragment.methodName();
            }
        });
    }
}