为什么我在 android-pageradapter 中出现 stackoverflow 错误？

Question

i just want to inflate one xml file and show it in viewpager pages.

会

logcat:

FATAL EXCEPTION: main java.lang.WhosebugError at android.graphics.drawable.BitmapDrawable.setAlpha(BitmapDrawable.java:406) at android.graphics.drawable.DrawableContainer.jumpToCurrentState(DrawableContainer.java:179) at android.widget.CompoundButton.jumpDrawablesToCurrentState(CompoundButton.java:319) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) at android.view.ViewGr

pageradapter class:

public class pageradapter extends PagerAdapter {
    Context mContext;
    LayoutInflater mLayoutInflater;
    List<String> l = MainActivity.list;
    ImageLoader mImageLoader;

    public pageradapter(Context context) {
        mContext = context;

        mLayoutInflater = LayoutInflater.from(mContext.getApplicationContext());

    }

    @Override
    public int getCount() {
        return 4;
    }


    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        //  View itemView = mLayoutInflater.inflate(R.layout.img, container, false);
        //   ImageLoader mImageLoader = ImageLoader.getInstance();


        View view = mLayoutInflater.inflate(R.layout.createnew, container);

        //   ImageView imageView = (ImageView) itemView.findViewById(R.id.imageView3);
        //  mImageLoader.displayImage("http://www.airtel.in/4g/images/airtel_4g_hotspot_responsive.jpg", imageView);

        container.addView(view);

        return view;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((LinearLayout) object);
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;
    }
}

xml 我要膨胀并在 viewpager 中显示的文件，所有 4 页都相同：->

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New RadioButton"
        android:id="@+id/radioButton"
        android:layout_gravity="center_horizontal" />

    <Switch
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New Switch"
        android:id="@+id/switch1"
        android:layout_gravity="center_horizontal" />
</LinearLayout>

Answer 1

您的 instantiateItem() returns ViewPager 的容器视图而不是要放入容器中的项目。

这是 inflate() 的一个特殊问题，之前可能已经被很多人咬过：如果你调用 inflate(R.layout.createnew, container)，它 returns 容器视图：

Returns

The root View of the inflated hierarchy. If root was supplied, this is the root View; otherwise it is the root of the inflated XML file.

（强调部分是我的）

您无法访问膨胀层次结构的实际根，只能访问已附加新子视图的容器。

在这种情况下，addView()实际上是多余的，因为新视图已经在容器中。但是，在您的代码中，它将容器添加到自身。 Android 不检查视图层次结构中的循环，但在某些时候会出现无限遍历循环（导致 WhosebugError）。

自instanceItem()needs to return the (child) view以来，这个有点问题：

Returns an Object representing the new page. This does not need to be a View, but can be some other container of the page.

要防止将新视图添加到容器中，请将调用更改为

View view = inflate(R.layout.createnew, container, false);

并按原样保留对 addView() 的调用。现在有必要，因为适配器是 required to add the view to the container:

The adapter is responsible for adding the view to the container given here, [...]

为什么我在 android-pageradapter 中出现 stackoverflow 错误？

Why am i getting stackoverflow error in android-pageradapter?

stack-overflow

android

android-layout

android-viewpager

android-pageradapter