Question

这段代码非常简单。我有一个ViewPager里面有几个Fragment。并添加“添加新寻呼机”按钮，将新寻呼机添加到ViewPager的第一个位置。

这是我的代码

public class TestPagerActivity extends SherlockFragmentActivity {

    private ArrayList<String> mData = new ArrayList<String>();
    private ViewPager mPager;
    private TestPagerAdapter mAdapter;

    @Override
    protected void onCreate(Bundle b) {
        // TODO Auto-generated method stub
        super.onCreate(b);
        setContentView(R.layout.testpager);

        mData.add("Looking");
        mData.add("into");
        mData.add("your");
        mData.add("dark");
        mData.add("blue");
        mData.add("eyes");
        mPager = (ViewPager) findViewById(R.id.pager);
        mAdapter = new TestPagerAdapter(getSupportFragmentManager(), mData);
        mPager.setAdapter(mAdapter);
    }

    public void onAddNewPagerClick(View v) {
        mData.add(0, "When");
        mAdapter.notifyDataSetChanged();
        mPager.invalidate();
    }

    public static class TestPagerAdapter extends FragmentStatePagerAdapter {

        private List<String> mData;

        public TestPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        public TestPagerAdapter(FragmentManager fm, List<String> data) {
            super(fm);
            mData = data;
        }

        public void updateAdapter(List<String> data) {
            mData = data;
            notifyDataSetChanged();
        }

        @Override
        public Fragment getItem(int position) {
            return TestFragment.newInstance(mData.get(position), position + "/" + mData.size());
        }

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

    }

    public static class TestFragment extends SherlockFragment {
        private static final String KEY_CONTENT = "TestFragment:Content";
        private static final String KEY_POSITION = "TestFragment:Position";

        public static TestFragment newInstance(String content, String position) {
            TestFragment fragment = new TestFragment();

            StringBuilder builder = new StringBuilder();
            builder.append("Page ").append(position).append("\n");
            for (int i = 0; i < 20; i++) {
                builder.append(content).append(" ");
            }
            builder.deleteCharAt(builder.length() - 1);
            fragment.mContent = builder.toString();

            return fragment;
        }

        private String mContent = "???";
        private String mPosition = "x/y";

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            if ((savedInstanceState != null) && savedInstanceState.containsKey(KEY_CONTENT)) {
                mContent = savedInstanceState.getString(KEY_CONTENT);
                mPosition = savedInstanceState.getString(KEY_POSITION);
            }
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            TextView text = new TextView(getActivity());
            text.setGravity(Gravity.CENTER);
            text.setText(mContent);
            text.setTextSize(20 * getResources().getDisplayMetrics().density);
            text.setPadding(20, 20, 20, 20);

            LinearLayout layout = new LinearLayout(getActivity());
            layout.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
            layout.setGravity(Gravity.CENTER);
            layout.addView(text);

            return layout;
        }

        @Override
        public void onSaveInstanceState(Bundle outState) {
            super.onSaveInstanceState(outState);
            outState.putString(KEY_CONTENT, mContent);
            outState.putString(KEY_POSITION, mPosition);
        }
    }
}

问题是：在添加新的寻呼机后刷新ViewPager时，其内容无法正确显示。一开始，我有6页，但在添加一个新页面之后，这里仍然显示6页，而我希望有7页。

谁能告诉我这里有什么问题？谢谢你的任何建议。

Answer 1

首先要注意的是，您在页面列表的前面插入了新项目，但是您还没有实现PagerAdapter方法getItemPosition(Object)来告诉ViewPager页面移动后的位置数据集的变化。正如该方法的文档所述，默认实现报告页面永远不会改变位置。如果适配器未正确实现此方法，则具有更改位置的页面的ViewPager将无法正常运行。

Answer 2

避免使用FragmentPagerAdapter并使用FragmentStatePagerAdapter。

我希望它也适合你。

无法刷新ViewPager内容

2 个答案: