fragment传值给activity：接口

步骤

1、fragment中定义接口，并设置数据

2、activity实现接口

示例：

FragmentA ：发送方

public class FragmentA extends Fragment {

    private EditText et;
    private FragmentACallBack fragmentACallBack;

    public interface FragmentACallBack {//定义接口
        void setData(String data);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        fragmentACallBack = (FragmentACallBack) getActivity();//实例化接口
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.layout_a, container, false);

        et = (EditText) view.findViewById(R.id.et);
        Button bt = (Button) view.findViewById(R.id.bt);
        bt.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                fragmentACallBack.setData(et.getText().toString());//接口传递数据
            }
        });
        return view;
    }


}

布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#00ff00"
    android:gravity="center"
    android:orientation="vertical">

    <EditText
        android:id="@+id/et"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="30sp" />

    <Button
        android:id="@+id/bt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="发送"
        android:textSize="30sp" />

LinearLayout>

MainActivityII ：接收方

public class MainActivityII extends FragmentActivity implements FragmentA.FragmentACallBack {

    private FragmentA fragmentA;

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

        fragmentA = new FragmentA();
        //添加fragment
        getFragmentManager().beginTransaction().replace(R.id.container_a, fragmentA, "fragmentA").commit();
    }


    @Override
    public void setData(String data) {//实现接口

        //获取到FragmentA传递过来的数据data

    }
}

布局：

<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/container_a"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="@color/colorAccent"
        android:orientation="horizontal" />
LinearLayout>