我遇到了以下问题 :我正在使用 fragment 制作一个 android webview 应用程序，并且我想实现一个 SwipeToRefresh 操作。

我试图这样做，但应用程序在用户的拉动刷新操作后立即停止。
以下是不同的代码:

fragment_home.xml :

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:background="@android:color/holo_red_light"> 
 
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout 
    android:id="@+id/sr" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 
 
    <WebView 
        android:id="@+id/webviewhome" 
        android:layout_width="match_parent" 
        android:layout_height="match_parent"></WebView> 
 
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout> 
 
</RelativeLayout>     

public HomeFragment(){ 
    // Required 
} 
 
private SwipeRefreshLayout mRefreshLayout; 
private WebView mWebView; 
 
@Nullable 
@Override 
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
 
    View v = inflater.inflate(R.layout.fragment_home, container, false); 
    mRefreshLayout = (SwipeRefreshLayout) v.findViewById(R.id.sr); 
    mRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { 
        @Override 
        public void onRefresh() { 
            mWebView.reload(); 
            mRefreshLayout.setRefreshing(false); 
        } 
    }); 
    final WebView webView = (WebView) v.findViewById(R.id.webviewhome); 
    webView.getSettings().setJavaScriptEnabled(true); 
    webView.getSettings().setAppCacheEnabled(true); 
    webView.loadUrl("MYURL"); 
    webView.setWebViewClient(new WebViewClient()); 
    webView.canGoBack(); 
 
    webView.setOnKeyListener(new View.OnKeyListener() { 
        public boolean onKey(View v, int keyCode, KeyEvent event) { 
            if (keyCode == KeyEvent.KEYCODE_BACK 
                    && event.getAction() == MotionEvent.ACTION_UP 
                    && webView.canGoBack()) { 
                webView.goBack(); 
                return true; 
            } 
            return false; 
        } 
    }); 
 
    webView.setWebViewClient(new WebViewClient() { 
        public void onReceivedError(WebView webView, int errorCode, String description, String failingUrl) { 
            try { 
                webView.stopLoading(); 
            } catch (Exception e) { 
            } 
 
            if (webView.canGoBack()) { 
                webView.goBack(); 
            } 
 
            webView.loadUrl("about:blank"); 
            AlertDialog alertDialog = new AlertDialog.Builder(getContext()).create(); 
            alertDialog.setTitle("Erreur !"); 
            alertDialog.setMessage("Veuillez vérifier votre connexion internet et réessayer"); 
            alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "Réessayer", new DialogInterface.OnClickListener() { 
                public void onClick(DialogInterface dialog, int which) { 
                    getActivity().finish(); 
                    startActivity(getActivity().getIntent()); 
                } 
            }); 
 
            alertDialog.show(); 
            super.onReceivedError(webView, errorCode, description, failingUrl); 
        } 
    }); 
 
    return v; 
}     

请您参考如下方法:

如果我们没有遗漏您的部分代码，那么您已经为 webview 创建了两个实例，在刷新布局中您正在调用尚未初始化的 mWebView。
试试这个:

public HomeFragment(){ 
    // Required 
} 
 
private SwipeRefreshLayout mRefreshLayout; 
private WebView WebView; 
 
@Nullable 
@Override 
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
 
View v = inflater.inflate(R.layout.fragment_home, container, false); 
mRefreshLayout = (SwipeRefreshLayout) v.findViewById(R.id.sr); 
mRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { 
    @Override 
    public void onRefresh() { 
        mWebView.reload(); 
        mRefreshLayout.setRefreshing(false); 
    } 
}); 
webView = (WebView) v.findViewById(R.id.webviewhome); 
webView.getSettings().setJavaScriptEnabled(true); 
webView.getSettings().setAppCacheEnabled(true); 
webView.loadUrl("MYURL"); 
webView.setWebViewClient(new WebViewClient()); 
webView.canGoBack(); 
 
webView.setOnKeyListener(new View.OnKeyListener() { 
    public boolean onKey(View v, int keyCode, KeyEvent event) { 
        if (keyCode == KeyEvent.KEYCODE_BACK 
                && event.getAction() == MotionEvent.ACTION_UP 
                && webView.canGoBack()) { 
            webView.goBack(); 
            return true; 
        } 
        return false; 
    } 
}); 
 
webView.setWebViewClient(new WebViewClient() { 
    public void onReceivedError(WebView webView, int errorCode, String description, String failingUrl) { 
        try { 
            webView.stopLoading(); 
        } catch (Exception e) { 
        } 
 
        if (webView.canGoBack()) { 
            webView.goBack(); 
        } 
 
        webView.loadUrl("about:blank"); 
        AlertDialog alertDialog = new AlertDialog.Builder(getContext()).create(); 
        alertDialog.setTitle("Erreur !"); 
        alertDialog.setMessage("Veuillez vérifier votre connexion internet et réessayer"); 
        alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "Réessayer", new DialogInterface.OnClickListener() { 
            public void onClick(DialogInterface dialog, int which) { 
                getActivity().finish(); 
                startActivity(getActivity().getIntent()); 
            } 
        }); 
 
        alertDialog.show(); 
        super.onReceivedError(webView, errorCode, description, failingUrl); 
    } 
}); 
 
    return v; 
}