使用應用程序時無法查看進度條（水平）。 （導航抽屜）

Question

我已經使用Android Studio的導航抽屜（模板）。根據教程，我可以在'content_main'xml中輕鬆看到進度條。然而，每當活動開始時，進度條就沒有可見的地方。我已經嘗試了很多教程，包括使用FrameLayout代替ConstraintLayout，使用線性佈局使用工具欄內的進度條。請幫助我。 'content_main'的代碼如下所示。

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
app:layout_behavior="@string/appbar_scrolling_view_behavior" 
tools:context="parts.tractor.versa.com.versatractorparts.MainActivity" 
tools:showIn="@layout/app_bar_main"> 

<ProgressBar 
    android:id="@+id/progressBar" 
    style="?android:attr/progressBarStyleHorizontal" 
    android:layout_width="match_parent" 
    android:layout_height="40dp" 
    android:layout_gravity="top" 
    android:progressDrawable="@drawable/bg_progress_bar_webview"/> 

<WebView 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:id="@+id/webView"/> 

和Java文件如下：

webView = (WebView) findViewById(R.id.webView); 
    mProgressBar = (ProgressBar) findViewById(R.id.progressBar); 
    final Activity activity = this; 
    webView.setWebChromeClient(new WebChromeClient() 
    { 
     public void onProgressChanged(WebView view, int progress) { 
      // Activities and WebViews measure progress with different scales. 
      // The progress meter will automatically disappear when we reach 100% 
      activity.setProgress(progress * 100); 
     } 
    }); 

    webView.setWebViewClient(new WebViewClient(){ 

     public boolean shouldOverrideUrlLoading(WebView view, String url) { 
      view.loadUrl(url); 
      return true; 
     } 

     @Override 
     public void onPageStarted(WebView view, String url, Bitmap favicon) { 
      super.onPageStarted(view, url, favicon); 
      mProgressBar.setVisibility(View.VISIBLE); 
     } 

     @Override 
     public void onPageFinished(WebView view, String url) { 
      super.onPageFinished(view, url); 
      mProgressBar.setVisibility(View.GONE); 
     } 
    }); 

Answer 1

傳遞您的網址與默認進度此方法。

private void startWebView(String url) { 

    WebSettings settings = webView.getSettings(); 

    settings.setJavaScriptEnabled(true); 
    webView.setScrollBarStyle(View.SCROLLBARS_OUTSIDE_OVERLAY); 

    webView.getSettings().setBuiltInZoomControls(true); 
    webView.getSettings().setUseWideViewPort(true); 
    webView.getSettings().setLoadWithOverviewMode(true); 

    progressDialog = new ProgressDialog(ContestActivity.this); 
    progressDialog.setMessage("Loading..."); 
    progressDialog.show(); 

    webView.setWebViewClient(new WebViewClient() { 
     @Override 
     public boolean shouldOverrideUrlLoading(WebView view, String url) { 
      view.loadUrl(url); 
      return true; 
     } 

     @Override 
     public void onPageFinished(WebView view, String url) { 
      if (progressDialog.isShowing()) { 
       progressDialog.dismiss(); 
      } 
     } 

     @Override 
     public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) { 
      Toast.makeText(ContestActivity.this, "Error:" + description, Toast.LENGTH_SHORT).show(); 

     } 
    }); 
    webView.loadUrl(url); 
}