为什么我在android-pageradapter中遇到stackoverflow错误？

Question

我只是想膨胀一个xml文件并在viewpager页面中显示它.

LLL

logcat的:

致命异常:在Android.wits.CompoundButton的android.graphics.drawable.DrawableContainer.jumpToCurrentState(DrawableContainer.java:179)上的android.graphics.drawable.BitmapDrawable.setAlpha(BitmapDrawable.java:406)中的主要java.lang.StackOverflowError. android.view.View.jumpDrawablesToCurrentState(ViewGroup.java:5158)在android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的jumpDrawablesToCurrentState(CompoundButton.java:319) :5158)在android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)at android位于android.view的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.View.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158).位于android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)位于android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup) .java:5158)在android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的android.view.View.jumpDrawablesToCurrentState(ViewGroup.java:5158)在Android.view上的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.View.View.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158).位于android.view.View.View.jumpDrawablesTo的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)位于android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.View.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的CurrentState(ViewGroup.java:5158),位于android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java) :5158)在android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)at android位于android.view.ViewGroup的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158). android.view.View.jumpDrawablesToCurrentState(ViewGroup.java:5158)在android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.View.jumpDrawablesToCurrentState(ViewGroup.ja)上的jumpDrawablesToCurrentState(ViewGroup.java:5158)va:5158)在android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)上的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) android.view.View.View.View上的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)安卓android.view.View上的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)位于android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.View.jumpDrawablesToCurrentState(ViewGroup.java:5158)的.jumpDrawablesToCurrentState(ViewGroup.java:5158)位于android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup. java:5158)在android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)的android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158)android.view.ViewGroup.jumpDrawablesToCurrentState(ViewGroup.java:5158) android.view.ViewGr

pageradapter类:

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;
    }
}

我希望膨胀并在viewpager中显示的xml文件,在所有4个页面中都相同: - >

<?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instantiateItem()返回容器视图,ViewPager而不是要进入容器内的项目.

这是一个特别的肮脏inflate(),之前可能已经咬了很多:如果你调用inflate(R.layout.createnew, container),它会返回容器视图:

返回

膨胀层次结构的根视图.如果提供了root,则这是根视图 ; 否则它是膨胀的XML文件的根.

(重点部分是我的)

您无法访问已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,因为新的View已经在容器中.但是,在您的代码中,它会将容器添加到自身.Android不检查视图层次结构中的循环,但是在某些时候会得到无限的遍历循环(导致StackOverflowError).

由于instanceItem() 需要返回(子)视图,这是一个小问题:

返回表示新页面的Object.这不需要是View,但可以是页面的其他容器.

要阻止将新视图添加到容器,请将调用更改为

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

然后保持呼叫addView()原样.现在需要,因为需要适配器将视图添加到容器:

适配器负责将视图添加到此处给出的容器中,[...]