Android - 如何将数据从活动传递到片段？

Question

我需要将数据从活动传递到片段.我知道我可以使用bundle,但是一旦我传递数据,我就无法在不调用和再次创建片段的情况下发送数据.

在我的活动中,有些东西可能会被更改,我需要通知我的片段这些更改而不重新创建片段.

Answer 1

创建一个interface在你Activity并通过你传递数据interface的fragment.interface在您的实现中fragment获取数据.

例如

MainActivity.class

public class MainActivity extends AppCompatActivity {

    DataFromActivityToFragment dataFromActivityToFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        FragmentA fr = new FragmentA();
        FragmentManager fm = getFragmentManager();
        dataFromActivityToFragment = (DataFromActivityToFragment) fr;
        FragmentTransaction fragmentTransaction = fm.beginTransaction();
        fragmentTransaction.replace(R.id.fragment_place, fr);
        fragmentTransaction.commit();


        final Handler handler = new Handler();

        final Runnable r = new Runnable() {
            public void run() {
                dataFromActivityToFragment.sendData("Hi");
            }
        };

        handler.postDelayed(r, 5000);


    }

    public interface DataFromActivityToFragment {
        void sendData(String data);
    }
}

FragmentA.class

public class FragmentA extends Fragment implements MainActivity.DataFromActivityToFragment {

    TextView text;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.content_main, null);
        text = (TextView) rootView.findViewById(R.id.fragment_text);

        return rootView;
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
    }

    @Override
    public void sendData(String data) {
        if(data != null)
        text.setText(data);
    }
}

activity_main.xml中

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/fragment_place"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
    </LinearLayout>

</LinearLayout>

content_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/fragment_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

在上面的例子中,我Runnable只是在创建后发送延迟5秒的数据fragment.

Answer 2

Fragment 对象就像其他对象一样。像 String 一样，您可以调用字符串对象的方法， str.charAt(0) ，str.toUpperCase() 等。只需在 Fragment 中创建一个函数，将代码放在那里并调用该函数价值观

Inside Activity {
  fragDemoObject.doWhatYouWant("this is passed as string object to fragment");
}

Inside FragmentDemo{
  void doWhatYouWant(String input){
     System.out.println(input);
    // do what else you want to do with code
  }

}