Fragment与Activity及Fragment与Fragment之间通信

Fragment Activity之间通信

FragmentFirst 布局

<TextView
    android:id="@+id/text_first"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="FragmentFirst"
    ... />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button1"
    app:layout_constraintTop_toBottomOf="@+id/text_first"
    .../>

MainActivity 布局

<fragment
    android:id="@+id/fragment1"
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:layout_weight="1"
    android:name="com.jimzjy.test2.FragmentFirst"/>

1.通过接口通信

在FragmentFirst中定义 onButtonClick 接口

public class FragmentFirst extends android.app.Fragment {

    Button button1;
    onButtonClick mCallback;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_1,container,false);

        button1 = view.findViewById(R.id.button1);

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mCallback.onButtonClick1();
            }
        });
        return view;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context != null) {
            mCallback = (onButtonClick) context;
        }
    }

    public interface onButtonClick {
        void onButtonClick1();
    }
}

通过在MainActivity中对 onButtonClick1() 的实现来进行通信

@Override
public void onButtonClick1() {
    //do something
}

2.在Fragment中调用Activity的方法

FragmentFirst

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_1,container,false);

    button1 = view.findViewById(R.id.button1);

    button1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            MainActivity activity = (MainActivity) getActivity();
            activity.onButtonClick1();
        }
    });
    return view;
}

Fragment之间通信

改变MainActivity布局,添加一个装第二个Fragment的容器

<fragment
    android:id="@+id/fragment1"
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:layout_weight="1"
    android:name="com.jimzjy.test2.FragmentFirst"/>

<FrameLayout
    android:id="@+id/right_layout"
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:layout_weight="1">
</FrameLayout>

MainActivity 中动态加载 FragmentSecond

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

    replaceFragment(new FragmentSecond());
}

private void replaceFragment(Fragment fragment){
    FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.replace(R.id.right_layout,fragment,"fragment2");
    fragmentTransaction.commit();
}

修改MainActivity中onButtonClicl1()的实现

@Override
public void onButtonClick1() {
    FragmentSecond fragmentSecond = (FragmentSecond) getFragmentManager().findFragmentByTag("fragment2");
    fragmentSecond.textView.setText("1");
}

1.png

点击按钮之后

2.png

还可以在Fragment中直接去取得另一个Fragment的实例来通信,但是尽量不要使用