我有ViewPager,但从未调用过onPageSelected
函数。我研究了所有stackoverflow问题,并尝试了所有答案,但是没有用。
我的viewPager具有gridview。我想听从viewPager的左右滑动。
布局:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerInParent="true"
android:layout_centerVertical="true"
android:layout_gravity="center"
android:layout_margin="10dp"
android:gravity="center"
android:textColor="@color/bg_yellow"
android:textSize="20sp" />
<androidx.viewpager.widget.ViewPager
android:id="@+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/textView"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</RelativeLayout>
代码:
this.viewPager = findViewById(R.id.viewPager);
currentPosition = viewPager.getCurrentItem();
viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
if (currentPosition < position) {
pressNext();
} else if (currentPosition > position) {
pressBack();
}
currentPosition = position;
}
});
MyViewPagerAdapter myViewPagerAdapter = new MyViewPagerAdapter(mContext);
viewPager.setAdapter(myViewPagerAdapter);
ViewPagerAdapter:
public class MyViewPagerAdapter extends PagerAdapter {
private Context context;
private MyGridViewAdapter myGridViewAdapter;
public MyViewPagerAdapter(Context context) {
this.context = context;
myGridViewAdapter = new MyViewPagerAdapter(context);
}
public int getCount() {
return 10;
}
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object obj) {
return view == obj;
}
@Override
public void destroyItem(ViewGroup container, int position, @NonNull Object object) {
container.removeView((GridView) object);
}
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
View view = LayoutInflater.from(context).inflate(R.layout.viewpager_item, null);
GridView gridView = view.findViewById(R.id.grid);
gridView.setAdapter(myGridViewAdapter);
container.addView(view);
return view;
}
尝试
ViewPager viewPager = findViewById(R.id.viewPager);
而不是:
this.viewPager = findViewById(R.id.viewPager);