我正在使用兼容性库中的ViewPager。我已经成功地让它显示几个视图,我可以通过页面。

但是,我很难弄清楚如何用一组新的视图更新ViewPager。

我已经尝试了各种各样的事情,比如调用mAdapter.notifyDataSetChanged(), mviewpage .invalidate(),甚至在每次我想使用新的数据列表时创建一个全新的适配器。

没有任何帮助,textviews保持不变,从原始数据。

更新: 我做了一个小测试项目,我几乎能够更新视图。我将在下面粘贴这个类。

然而,似乎没有更新的是第二个视图,“B”仍然存在,它应该在按下更新按钮后显示“Y”。

public class ViewPagerBugActivity extends Activity {

    private ViewPager myViewPager;
    private List<String> data;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        data = new ArrayList<String>();
        data.add("A");
        data.add("B");
        data.add("C");

        myViewPager = (ViewPager) findViewById(R.id.my_view_pager);
        myViewPager.setAdapter(new MyViewPagerAdapter(this, data));

        Button updateButton = (Button) findViewById(R.id.update_button);
        updateButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                updateViewPager();
            }
        });
    }

    private void updateViewPager() {
        data.clear();
        data.add("X");
        data.add("Y");
        data.add("Z");
        myViewPager.getAdapter().notifyDataSetChanged();
    }

    private class MyViewPagerAdapter extends PagerAdapter {

        private List<String> data;
        private Context ctx;

        public MyViewPagerAdapter(Context ctx, List<String> data) {
            this.ctx = ctx;
            this.data = data;
        }

        @Override
        public int getCount() {
            return data.size();
        }

        @Override
        public Object instantiateItem(View collection, int position) {
            TextView view = new TextView(ctx);
            view.setText(data.get(position));
            ((ViewPager)collection).addView(view);
            return view;
        }

        @Override
        public void destroyItem(View collection, int position, Object view) {
             ((ViewPager) collection).removeView((View) view);
        }

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

        @Override
        public Parcelable saveState() {
            return null;
        }

        @Override
        public void restoreState(Parcelable arg0, ClassLoader arg1) {
        }

        @Override
        public void startUpdate(View arg0) {
        }

        @Override
        public void finishUpdate(View arg0) {
        }
    }
}

当前回答

在ViewPager2中,您可以重新初始化适配器,用新的视图刷新页导航列表。viewPager2。adapter = myPagerAdapter

其他回答

我使用Tablayout与ViewPagerAdapter。为了在片段之间传递数据或在片段之间进行通信,使用下面的代码,它工作得非常好,并在片段出现时刷新它。第二段点击按钮里面写下面的代码。

b.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            String text=e1.getText().toString(); // get the text from EditText

            // move from one fragment to another fragment on button click
            TabLayout tablayout = (TabLayout) getActivity().findViewById(R.id.tab_layout); // here tab_layout is the id of TabLayout which is there in parent Activity/Fragment
            if (tablayout.getTabAt(1).isSelected()) { // here 1 is the index number of second fragment i-e current Fragment

                LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(getContext());
                Intent i = new Intent("EDIT_TAG_REFRESH");
                i.putExtra("MyTextValue",text);
                lbm.sendBroadcast(i);

            }
            tablayout.getTabAt(0).select(); // here 0 is the index number of first fragment i-e to which fragment it has to moeve

        }
    });

下面是必须在第一个片段(在我的情况下)i-e中接收片段的代码。

MyReceiver r;
Context context;
String newValue;
public void refresh() {
    //your code in refresh.
    Log.i("Refresh", "YES");
}
public void onPause() {
    super.onPause();

    LocalBroadcastManager.getInstance(context).unregisterReceiver(r);
}
public void onResume() {
    super.onResume();
    r = new MyReceiver();
    LocalBroadcastManager.getInstance(getActivity()).registerReceiver(r,
            new IntentFilter("EDIT_TAG_REFRESH"));
} // this code has to be written before onCreateview()


 // below code can be written any where in the fragment
 private class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
    PostRequestFragment.this.refresh();
        String action = intent.getAction();
        newValue=intent.getStringExtra("MyTextValue");
        t1.setText(newValue); // upon Referesh set the text
    }
}

我实际上使用notifyDataSetChanged()在ViewPager和CirclePageIndicator和之后,我调用destroyDrawingCache()在ViewPager和它的工作。其他的解决方法对我都不起作用。

我发现这个问题的决定很有趣。 我们可以使用FragmentStatePagerAdapter (android.support.v4.app.FragmentStatePagerAdapter),而不是使用FragmentPagerAdapter将所有片段保存在内存中,当我们每次选择fragment时,它都会重新加载fragment。

两个适配器的实现是相同的。我们只需要在extend FragmentStatePagerAdapter上修改extend FragmentPagerAdapter

1.首先,您必须在Pageradapter类中设置getItemposition方法 2.您必须阅读您的视图寻呼机的确切位置 3.然后将该位置作为新位置的数据位置发送 4.在setonPageChange监听器中写入更新按钮的点击监听器

我修改了程序代码,只设置了特定的位置元素

public class MyActivity extends Activity {

private ViewPager myViewPager;
private List<String> data;
public int location=0;
public Button updateButton;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    data = new ArrayList<String>();
    data.add("A");
    data.add("B");
    data.add("C");
    data.add("D");
    data.add("E");
    data.add("F");

    myViewPager = (ViewPager) findViewById(R.id.pager);
    myViewPager.setAdapter(new MyViewPagerAdapter(this, data));

      updateButton = (Button) findViewById(R.id.update);

    myViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int i, float v, int i2) {
             //Toast.makeText(MyActivity.this, i+"  Is Selected  "+data.size(), Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onPageSelected( int i) {
          // here you will get the position of selected page
            final int k = i;
             updateViewPager(k);

        }

        @Override
        public void onPageScrollStateChanged(int i) {

        }
    });
}

private void updateViewPager(final int i) {  
    updateButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(MyActivity.this, i+"  Is Selected  "+data.size(), Toast.LENGTH_SHORT).show();
            data.set(i, "Replaced "+i);         
            myViewPager.getAdapter().notifyDataSetChanged();
        }
    });

}

private class MyViewPagerAdapter extends PagerAdapter {

    private List<String> data;
    private Context ctx;

    public MyViewPagerAdapter(Context ctx, List<String> data) {
        this.ctx = ctx;
        this.data = data;
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }

    @Override
    public Object instantiateItem(View collection, int position) {          

        TextView view = new TextView(ctx);
        view.setText(data.get(position));
        ((ViewPager)collection).addView(view);            
        return view;
    }

    @Override
    public void destroyItem(View collection, int position, Object view) {
         ((ViewPager) collection).removeView((View) view);
    }

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

    @Override
    public Parcelable saveState() {
        return null;
    }

    @Override
    public void restoreState(Parcelable arg0, ClassLoader arg1) {
    }

    @Override
    public void startUpdate(View arg0) {
    }

    @Override
    public void finishUpdate(View arg0) {
    }
}
}

我也有同样的问题。对我来说,它可以扩展FragmentStatePagerAdapter,并覆盖以下方法:

@Override
public Parcelable saveState() {
    return null;
}

@Override
public void restoreState(Parcelable state, ClassLoader loader) {

}