Android webview中的我的progressbar返回null并崩溃?
我正在尝试将progressbar添加到webview类中。但是,即使正确地执行了所有步骤,它也会因空指针异常而崩溃,你知道为什么吗? 以下是我的主要活动:Android webview中的我的progressbar返回null并崩溃?,android,android-layout,android-webview,android-linearlayout,android-progressbar,Android,Android Layout,Android Webview,Android Linearlayout,Android Progressbar,我正在尝试将progressbar添加到webview类中。但是,即使正确地执行了所有步骤,它也会因空指针异常而崩溃,你知道为什么吗? 以下是我的主要活动: public class MainActivity extends Activity { WebView webview; ProgressBar progress; @Override public void onCreate(Bundle savedInstanceState){ sup
public class MainActivity extends Activity {
WebView webview;
ProgressBar progress;
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
// getWindow().requestFeature(Window.FEATURE_PROGRESS);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
webview = (WebView)findViewById(R.id.webview);
webview.setInitialScale(1);
WebSettings webSettings = webview.getSettings();
webSettings.setJavaScriptEnabled(true);
progress = (ProgressBar) webview.findViewById(R.id.ProgressBar);
progress.setVisibility(View.VISIBLE);
webview.getSettings().setJavaScriptEnabled(true);
webview.getSettings().setLoadWithOverviewMode(true);
webview.getSettings().setUseWideViewPort(true);
// webview.setWebViewClient(new MyCustomWebViewClient());
webview.setScrollBarStyle(View.SCROLLBARS_OUTSIDE_OVERLAY);
webview.setScrollbarFadingEnabled(false);
webview.getSettings().setRenderPriority(RenderPriority.HIGH);
webview.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);
// webview.getSettings().setBlockNetworkLoads(true);
webview.getSettings().setBuiltInZoomControls(true);
webview.loadUrl("http://www.yahoo.com");
webview.getSettings().setSupportZoom(false);
/* webview.setWebChromeClient(new WebChromeClient()
{
public void onProgressChanged(WebView view, int progress)
{
// update the progressBar
MainActivity.this.setProgress(progress * 100);
}
});*/
}
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(event.getAction() == KeyEvent.ACTION_DOWN){
switch(keyCode)
{
case KeyEvent.KEYCODE_BACK:
if(webview.canGoBack() == true){
webview.goBack();
}else{
finish();
}
return true;
}
}
return super.onKeyDown(keyCode, event);
}
private class MyCustomWebViewClient extends WebViewClient {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
public void onPageStarted(WebView view, String url, Bitmap favicon) {
progress.setVisibility(View.VISIBLE);
}
public void onPageFinished(WebView view, String url) {
progress.setVisibility(View.GONE);
}
}
}
下面是相应的xml:
main.xml
更改
progress = (ProgressBar) webview.findViewById(R.id.ProgressBar);
到
Progressbar
属于main.xml
findViewById
在当前展开的布局中查找视图。您已将layoutmain.xml的内容设置为您的活动。我看到您复制了一个示例,但您做得不对。将注释代码替换为以下内容:
webView.setWebChromeClient(new WebChromeClient()
{
public void onProgressChanged(WebView view, int prog)
{
progress.setProgress(prog * 100);
}
});
另外,正如在另一篇文章中所说的,webview.findViewById中的webview需要删除。的确如此,但在webview中内容转换时,它不会显示任何进度条,我如何解决该问题?使用来自的内置资产类jquery@JusticeBauer您已经对这个webview.setWebViewClient(新的MyCustomWebViewClient())进行了注释代码>你对这段代码有什么线索吗:,我在一个线程中包含了你建议的修复代码,但是我在checkmark.internetavailable上得到了错误,因为未定义
progress = (ProgressBar)findViewById(R.id.ProgressBar);
webView.setWebChromeClient(new WebChromeClient()
{
public void onProgressChanged(WebView view, int prog)
{
progress.setProgress(prog * 100);
}
});