javascript - 需要 WebView 的帮助

Question

    final Context myApp = this;      /* An instance of this class will be registered as a JavaScript interface */      class MyJavaScriptInterface      {          @SuppressWarnings("unused")          public void showHTML(String html)          {              new AlertDialog.Builder(myApp)                  .setTitle("HTML")                  .setMessage(html)                  .setPositiveButton(android.R.string.ok, null)              .setCancelable(false)              .create()              .show();          }      }      final WebView browser = (WebView)findViewById(R.id.browser);      /* JavaScript must be enabled if you want it to work, obviously */      browser.getSettings().setJavaScriptEnabled(true);      /* Register a new JavaScript interface called HTMLOUT */      browser.addJavascriptInterface(new MyJavaScriptInterface(), "HTMLOUT");      /* WebViewClient must be set BEFORE calling loadUrl! */      browser.setWebViewClient(new WebViewClient() {          @Override          public void onPageFinished(WebView view, String url)          {              /* This call inject JavaScript into the page which just finished loading. */              browser.loadUrl("javascript:window.HTMLOUT.showHTML(''+document.getElementsByTagName('html')[0].innerHTML+'');");          }      });      /* load a web page */      browser.loadUrl("http://lexandera.com/files/jsexamples/gethtml.html");  

进入上面的代码后

             new AlertDialog.Builder(myApp)                  .setTitle("HTML")                  .setMessage(html)                  .setPositiveButton(android.R.string.ok, null)              .setCancelable(false)              .create()              .show(); 

我想将按钮的可见性设置为 true 和 false，但它给了我错误，有人知道为什么会发生这种情况并有任何解决方案吗？提前致谢

Answer 1

终于找到了错误的解决方案。我正在使用:

btn.post(new Runnable() {
    @Override
    public void run() {
        btn.requestFocus();
        btn.setVisibility(0);
    }
}

之后，当我想显示按钮时，我将启动一个新线程