如何使用PagerAdapter重新填充Pagerview视图? [英] how to re-populate the Pagerview view using PagerAdapter?
本文介绍了如何使用PagerAdapter重新填充Pagerview视图?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
第一次运行正常.该应用程序可以从互联网下载图像并保存到外部存储中.
First time it works fine. this app download image from the internet and save into external storage.
当我调用该方法时，我想创建一个方法，它将重新填充外部存储中的图像，并设置新的适配器以显示PagerView上的所有图像.
I want to make a method when i call the method then it will repopulate the image from external storage and set new adapter to show the all images on PagerView.
简而言之，我想刷新pagerview屏幕视图.在应用程式上 开始在sdcard中有3张图片.当我按下按钮，然后那里 sdcard中有4张图片.它应该更新/刷新视图.
In simple words i want to refresh the pagerview screens view. on app start there is 3 images in sdcard. and when i press button then there is 4 images in sdcard. it should update/refresh the view.
这是自定义适配器类
public class CustomSwipeAdapter extends PagerAdapter {
static ImageView i1;
String pdfName;
static Bitmap[] bmp ;
private Context ctx;
private LayoutInflater layoutInflater;
public CustomSwipeAdapter(Context ctx) {
this.ctx =ctx;
}
@Override
public int getCount() {
bmp=Picgraber();
return bmp.length;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return (view==(LinearLayout)object);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
//Picgraber();
layoutInflater = (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View item_view = layoutInflater.inflate(R.layout.swipe_layout,container,false);
i1 = (ImageView)item_view.findViewById(R.id.swipeimageview);
TextView t1 = (TextView)item_view.findViewById(R.id.swipetextview);
// i1.setImageResource(images[position]);
i1.setImageBitmap(bmp[position]);
i1.setTag(imagesstr[position]);
t1.setText("image "+ position);
pdfName = String.valueOf(i1.getResources());
Log.d("pdfname", pdfName);
Log.d("position", String.valueOf(position));
container.addView(item_view);
return item_view;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((LinearLayout)object);
}
public Bitmap[] Picgraber(){
ArrayList<Bitmap> list = new ArrayList<Bitmap>();
File file= new File("/sdcard/com.shah.tabs/");
File[] folders=file.listFiles();
for(File ff:folders){
File it=new File(file.getPath()+File.separator+ff.getName()+File.separator+"image"+File.separator+ff.getName()+".png");
// Log.w("folder with path",it.getPath());
list.add(BitmapFactory.decodeFile(it.getPath()));
}
Bitmap[] Array = list.toArray(new Bitmap[list.size()]);
return Array;
}
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
public void update(){
bmp = Picgraber();
this.notifyDataSetChanged();
}
}
这是活动的onCreate方法
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_books);
packageFolder = new File(Environment.getExternalStorageDirectory() + File.separator + getApplicationContext().getPackageName());
if (!packageFolder.exists()) {
packageFolder.mkdir();
}
viewPager = (ViewPager) findViewById(R.id.viewpager);
adapter = new CustomSwipeAdapter(this);
viewPager.setAdapter(adapter);
Log.d("curritem", String.valueOf(viewPager.getCurrentItem()));
viewPager.setPageTransformer(true, new ZoomOutSlideTransformer());
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
public void onPageScrollStateChanged(int state) {}
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}
public void onPageSelected(int position) {
pos = position;
Log.d("onpagechange", String.valueOf(pos));
Log.d("imagename", String.valueOf(CustomSwipeAdapter.i1.getTag()));
}
});
viewPager.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: {
x1 = event.getX();
y1 = event.getY();
break;
}
case MotionEvent.ACTION_UP: {
x2 = event.getX();
y2 = event.getY();
if (x1 < x2) {
}
if (x1 > x2) {
}
if (y1 < y2) {
}
if (y1 > y2 + 100) {
downtoupswipe();
}
break;
}
}
return false;
}
});
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("file/*");
startActivityForResult(intent, 1);
}
});
}
这是崩溃时应用程序的日志
10-10 11:00:50.388 16816-16816/com.shah.tabs E/InputEventReceiver: Exception dispatching input event.
10-10 11:00:50.389 16816-16816/com.shah.tabs E/MessageQueue-JNI: Exception in MessageQueue callback: handleReceiveCallback
10-10 11:00:50.390 16816-16816/com.shah.tabs E/MessageQueue-JNI: java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count: 2, found: 3 Pager id: com.shah.tabs:id/viewpager Pager class: class android.support.v4.view.ViewPager Problematic adapter: class com.shah.tabs.CustomSwipeAdapter
at android.support.v4.view.ViewPager.populate(ViewPager.java:1071)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
at android.support.v4.view.ViewPager.onTouchEvent(ViewPager.java:2114)
at android.view.View.dispatchTouchEvent(View.java:8471)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2399)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2092)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2369)
at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1719)
at android.app.Activity.dispatchTouchEvent(Activity.java:2742)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2330)
at android.view.View.dispatchPointerEvent(View.java:8666)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4123)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3989)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3544)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3597)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3563)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3680)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3571)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3737)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3544)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3597)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3563)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3571)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3544)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5807)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5781)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5752)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5897)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:143)
at android.os.Looper.loop(Looper.java:122)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
10-10 11:00:50.390 16816-16816/com.shah.tabs D/AndroidRuntime: Shutting down VM
10-10 11:00:50.393 16816-16816/com.shah.tabs E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.shah.tabs, PID: 16816
java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count: 2, found: 3 Pager id: com.shah.tabs:id/viewpager Pager class: class android.support.v4.view.ViewPager Problematic adapter: class com.shah.tabs.CustomSwipeAdapter
at android.support.v4.view.ViewPager.populate(ViewPager.java:1071)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
at android.support.v4.view.ViewPager.onTouchEvent(ViewPager.java:2114)
at android.view.View.dispatchTouchEvent(View.java:8471)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2399)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2092)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2369)
at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1719)
at android.app.Activity.dispatchTouchEvent(Activity.java:2742)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2330)
at android.view.View.dispatchPointerEvent(View.java:8666)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4123)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3989)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3544)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3597)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3563)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3680)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3571)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3737)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3544)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3597)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3563)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3571)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3544)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5807)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5781)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5752)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5897)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:143)
at android.os.Looper.loop(Looper.java:122)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
**
**
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
adapter.update();
}
});
推荐答案
只要看看您在此处获得的Exception消息即可.它说:
Just take a look at the Exception message you got here. It says:
java.lang.IllegalStateException:应用程序的PagerAdapter 更改适配器的内容而无需调用 PagerAdapter#notifyDataSetChanged！预期的适配器项目数:2 找到:3
java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count: 2, found: 3
从异常"消息中可以很明显地看出，刷新PagerView时，您正在添加新图像，但并不是在告诉适配器要填充的数据已更改.结果，预期仅填充2张图像的适配器会发现3张图像，并且您的应用程序崩溃.
It is pretty clear from the Exception message that while refreshing your PagerView, you are adding new images but you are not telling the adapter that the data which it is going to populate has been changed. As a result, the adapter expecting to just populate 2 images find 3 images and your application crashes.
因此，每当添加新图像时，都需要显式调用adapter.notifyDataSetChanged()来告知adpater已添加了新图像，最终将解决此问题.
So whenever you add a new image you need to explicitly call adapter.notifyDataSetChanged() to tell the adpater that a new image has been added which would eventually solve this issue.
这篇关于如何使用PagerAdapter重新填充Pagerview视图?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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