如何更改 PagerAdapter 中 ImageButton 的可见性？

发布于 2025-01-01 03:22:17 字数 1149 浏览 1 评论 0原文

我想更改 PagerAdapter 中图像按钮的可见性。我似乎无法通过 id 引用 instantiateItem 中的部分布局，我只能引用完整的布局。但这很奇怪，因为似乎我仍然可以通过 id 引用我的网络视图。

我该如何处理这个问题？这就是我想要做的，但我在最后一行遇到空指针异常，如下所示：

    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);

...

        if (position != 2) {
            mainWebView = (WebView) view.findViewById(resId);
            mainWebView.getSettings().setJavaScriptEnabled(true);
            mainWebView.loadUrl(urltoload);

        }
        ((ViewPager) collection).addView(view, 0);
        return view;
    }

我需要位置来相应地设置可见性，所以我无法在 onCreate 中执行此操作。我知道对于普通适配器，我可以使用 getView，但不能将它用于 PagerAdapter。

我还读到我可以通过处理程序创建自己的 UI 更新线程，但在这种情况下我该怎么做？

谢谢。

原文

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.

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:

    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);

...

        if (position != 2) {
            mainWebView = (WebView) view.findViewById(resId);
            mainWebView.getSettings().setJavaScriptEnabled(true);
            mainWebView.loadUrl(urltoload);

        }
        ((ViewPager) collection).addView(view, 0);
        return view;
    }

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.

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?

Thanks.

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酒几许 2025-01-08 03:22:17

关于更新线程上的 UI 的问题，请查看 runOnUiThread 这里

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夜唯美灬不弃 2025-01-08 03:22:17

试试这个，其中“itemLayout”是您的布局：

View thisLayout = inflater.inflate(R.layout.itemLayout, null);

btnLeft = (ImageButton) thisLayout.findViewById(R.id.buttonleft);

<do stuff with btnLeft>

((ViewPager) collection).addView(thisLayout);

return thisLayout;

Try this, where "itemLayout" is your layout :

View thisLayout = inflater.inflate(R.layout.itemLayout, null);

btnLeft = (ImageButton) thisLayout.findViewById(R.id.buttonleft);

<do stuff with btnLeft>

((ViewPager) collection).addView(thisLayout);

return thisLayout;

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