title: How to Change Visibility of an ImageButton within a PagerAdapter?
body: <p>I want to change visibility of my image buttons within my PagerAdapter. It doesn't seem like I can refer to parts of a layout in instantiateItem through id, I can only refer to the full layout. This is strange though, because it seems that I can still refer to my webviews through id.</p>
  
  <p>How do I approach this? This is what I'm trying to do, but I'm getting a null pointer exception at the last line shown below:</p>
  
  <pre><code>    public Object instantiateItem(View collection, int position) {
          ImageButton btnRight = (ImageButton) findViewById(R.id.buttonright);
          ImageButton btnLeft = (ImageButton) findViewById(R.id.buttonleft);
          if (position == 0) {
              resLayout = R.layout.the_webview;
              urltoload = theUrls[position];
              resId = R.id.webview0;
              btnLeft.setVisibility(View.INVISIBLE);
          View view = inflater.inflate(resLayout, null);
  </code></pre>
  
  <p>...</p>
  
  <pre><code>        if (position != 2) {
              mainWebView = (WebView) view.findViewById(resId);
              mainWebView.getSettings().setJavaScriptEnabled(true);
              mainWebView.loadUrl(urltoload);
  
          }
          ((ViewPager) collection).addView(view, 0);
          return view;
      }
  </code></pre>
  
  <p>I need the position to set visibility accordingly, so I cannot do this in onCreate. I know for a normal adapter, I can use getView, but I cannot use it for PagerAdapter.</p>
  
  <p>I have also read that I can just create my own UI update thread through handlers, but how do I do that in this case?</p>
  
  <p>Thanks.</p>