如何使用PagerAdapter重新填充Pagerview视图？

时间：2016-10-10 06:24:01

标签： java android android-studio android-viewpager android-pageradapter

问题

第一次它工作正常。这个应用程序从互联网上下载图像并保存到外部存储。

我想在调用方法时创建一个方法然后它将从外部存储重新填充图像并设置新适配器以显示PagerView上的所有图像。

  

简单来说，我想刷新pagerview屏幕视图。在应用程序上   开始有sdcard中的3张图片。当我按下按钮然后那里   是sdcard中的4张图片。它应该更新/刷新视图。

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);

        }
    });

}

崩溃时应用程序的logcat 

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)

**

从活动工厂按钮

调用

** 

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            adapter.update();

        }
    });

2 个答案:

答案 0 :(得分：0)

使用位图数组会产生性能问题。您可以使用任何ImageLoader库来显示图像。

The Universal ImageLoader有显示本地图片的方法

在此课程中进行一些更改 CustomSwipeAdapter 

 @Override
 public int getCount() {
    return imagesstr.length();
}

//add this method 
public void setImages(String image[]){
    imagesstr = image;
    this.notifyDataSetChanged();
}
显示图片的

使用前面建议的imageLoader

答案 1 :(得分：0)

看看你在这里得到的异常消息。它说：

  

java.lang.IllegalStateException：应用程序的PagerAdapter   无需调用就更改了适配器的内容   PagerAdapter＃notifyDataSetChanged！预期的适配器项目数：2，   发现：3

从Exception消息中可以清楚地看到，在刷新PagerView时，您正在添加新图像，但您并未告诉适配器它将要填充的数据已被更改。因此，期望仅填充2个图像的适配器找到3个图像，并且您的应用程序崩溃。

因此，无论何时添加新图片，您都需要明确调用adapter.notifyDataSetChanged()告诉adpater已添加新图片，最终解决此问题。

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