Question

我有4个片段，使用view-pager和tabs在主要活动中显示新闻。但是我的代码只适用于第一个片段，即tab 1

在主要活动中我有

 @Override
    public void onBackPressed() {

        WebView mWebView = (WebView) findViewById(R.id.webview);
        if (mWebView.getVisibility() == View.VISIBLE) {
            mWebView.setVisibility(View.GONE);
            mWebView.loadUrl("about:blank");
        }
        else {

            super.onBackPressed();
        }

        return;
    }

因此，当按下后退按钮时，它会通过将用户带回主布局来隐藏Web视图。它适用于标签1

但是在片段2,3,4中 - 当我按下后退按钮时它会退出应用程序。我使用与片段1相同的代码

我发现 - mWebView.getVisibility（）== View.VISIBLE未实现 - 即使片段2,3,4的Web视图可见

片段1代码：

public class WSJFragment extends Fragment implements LoaderManager.LoaderCallbacks<List<News>> {


    .........


    public WSJFragment() {
        // Required empty public constructor
    }


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

        ............

        NewsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
                // Find the current earthquake that was clicked on
                News currentNews = mAdapter.getItem(position);


                String newsUrl = currentNews.getUrl();

                progress.setVisibility(View.VISIBLE);

                mWebView.setVisibility(View.VISIBLE);

                mWebView.loadUrl(newsUrl);

                mWebView.setWebViewClient(new WebViewClient() {
                    @Override
                    public void onPageFinished(WebView view, String url) {
                        super.onPageFinished(mWebView, url);
                        progress.setVisibility(View.GONE);

                    }

                });


            }


        });


        return rootView;
    }


    ........

}

https://embed.plnkr.co/hJ0NMmzGezjMzWfYufaV/

Answer 1

我已检入您的代码，进行此更改。

在MainActivity中替换为

@Override
public void onBackPressed() {

    if(mWebView != null){
        if (mWebView.getVisibility() == View.VISIBLE) {
            mWebView.setVisibility(View.GONE);
            mWebView.loadUrl("about:blank");
        }else {
            finish();
        }
    }else{ //if webview is null do something... here
    }
}

在所有4个片段中替换为

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

    MainActivity.mWebView = (WebView) rootView.findViewById(R.id.webview);
    MainActivity.mWebView.setVisibility(View.GONE);

   //your remaining code here

 return rootView;
}

在每个片段中，您找到＆＃34; mWebView＆＃34; 对象将其替换为 MainActivity.mWebView

后退按钮在WebView - Android中无法正常运行

1 个答案: