如何用SwipeToRefresh组件刷新Fragment？现有代码无法正常工作

XML布局代码 #

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/gradient_drawable"
    android:padding="10dp"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context=".Fragment_1">
    <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
        android:id="@+id/swipe"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
   
     <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ProgressBar
            android:id="@+id/progress"
            android:layout_width="76dp"
            android:layout_height="64dp"
            android:elevation="10dp"
            android:foregroundGravity="center"
            android:indeterminateTint="@color/black"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.84" />

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/listview"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            android:padding="5dp"/>


    </androidx.constraintlayout.widget.ConstraintLayout>
    </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

</FrameLayout>

Java代码（原代码） #

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

    View view=inflater.inflate(R.layout.fragment_1, container, false);

    newconfig= getResources().getConfiguration();
    db=new DBHandler(getActivity());
    swipeRefreshLayout=view.findViewById(R.id.swipe);
    recyclerView=view.findViewById(R.id.listview);
    progressBar=view.findViewById(R.id.progress);
    if(book.size()==0) {
        book = db.readCourses();
    }
    progressBar.setVisibility(View.GONE);
    BookFragAdapter adapter = new BookFragAdapter(Fragment_land1.this,book);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity(),RecyclerView.VERTICAL,false));
    recyclerView.setAdapter(adapter);
    swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
        @Override
        public void onRefresh() {
           this.onRefresh();
            getFragmentManager().beginTransaction().detach(Fragment_land1.this).attach(Fragment_land1.this).commit();
            swipeRefreshLayout.setRefreshing(false);
        }
    });


    return view;
}

问题描述 #

尝试刷新时，Fragment无法完成刷新，SwipeToRefresh的加载动画也不会自动停止，推测OnRefreshListener内的代码未执行。

问题原因及解决方案 #

核心问题 #

你在onRefresh()方法里调用了this.onRefresh();，这是无限递归调用，会导致方法一直循环自身，后面的detach/attach Fragment和setRefreshing(false)代码根本无法执行，自然会出现动画停不下来、Fragment不刷新的情况。

修复步骤 #

1. 移除递归调用：删掉this.onRefresh();这行代码。
2. 优化刷新逻辑：不需要通过detach/attach Fragment来刷新，直接重新加载数据并更新RecyclerView即可，这种方式更高效且避免Fragment重建的开销。

修改后的OnRefreshListener代码示例 #

swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
    @Override
    public void onRefresh() {
        // 重新从数据库加载数据
        book.clear();
        book.addAll(db.readCourses());
        // 通知适配器数据更新
        recyclerView.getAdapter().notifyDataSetChanged();
        // 停止刷新动画
        swipeRefreshLayout.setRefreshing(false);
    }
});

额外优化提示 #

如果数据库操作是耗时操作，建议放在子线程执行，避免阻塞主线程：

swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
    @Override
    public void onRefresh() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                // 子线程加载数据
                final List<Book> newBooks = db.readCourses();
                // 回到主线程更新UI
                getActivity().runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        book.clear();
                        book.addAll(newBooks);
                        recyclerView.getAdapter().notifyDataSetChanged();
                        swipeRefreshLayout.setRefreshing(false);
                    }
                });
            }
        }).start();
    }
});

内容的提问来源于stack exchange，提问作者Shakthi