android - 单击 fragment 中的后退按钮后应用程序关闭

Question

[更新]

问题已解决:只需在提交 fragment 之前添加“addToBackStack(null)”即可:

Fragment fragment = new WebBrowserFragment();
fragment.setArguments(arguments);
FragmentTransaction fragmentTransaction = getActivity().getFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.content_frame, fragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();

这是我的 fragment 的代码。当我在此 fragment 上并单击后退按钮时，我的应用程序已关闭。

我想返回上一个加载的 fragment 。

我能做些什么来强制这种行为？

public class WebBrowserFragment extends Fragment {

    WebView mWebView;
    ProgressBar progressB = null;
    private String mUrl;
    private static String mtitle;
    private static String msource;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        LayoutInflater mInflater = (LayoutInflater) getActivity().getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        View view =  (View) mInflater.inflate(R.layout.web_browser_view, null);

        MainActivity.setShareButtonToVisible();

        Bundle bundle = getArguments(); 
        String url = bundle.getString("URL");
        mtitle = bundle.getString("TITRE");
        msource = bundle.getString("SOURCE");

        mUrl = url;

        progressB = (ProgressBar) view.findViewById(R.id.progressBar1);

        mWebView = (WebView) view.findViewById(R.id.webViewArticle);
        mWebView.setWebChromeClient(new WebChromeClient() {
            public void onProgressChanged(WebView view, int progress) {
                if(progress < 100 && progressB.getVisibility() == ProgressBar.GONE){
                    progressB.setVisibility(ProgressBar.VISIBLE);
                }
                progressB.setProgress(progress);
                if(progress == 100) {
                    progressB.setVisibility(ProgressBar.GONE);
                }
            }
        });
        mWebView.loadUrl(url);  
        return view;
    }

Answer 1

将 fragment 附加到 Activity 时，您必须使用 FragmentTransaction.addToBackStack 方法。这是文档中的引述

Add this transaction to the back stack. This means that the transaction will be remembered after it is committed, and will reverse its operation when later popped off the stack.