在 ViewPager 中更改 TextView 的值

Question

我有以下问题，我有一个 ViewPager，Viewpager 包含一个 Fragment，这个 Fragment 包含一个 textview，其中包含一个 int 值（在本例中为 8000）。我想要的是一种在按下按钮 _Mas500 时获得 500 的方法。当我运行项目时出现此错误：

08-06 22:42:15.687: E/AndroidRuntime(8639): FATAL EXCEPTION: Thread-10

08-06 22:42:15.687: E/AndroidRuntime(8639): java.lang.IllegalStateException: Must be called from main thread of process

接受任何想法！谢谢！

这是我的代码：

public class MainActivity extends ActionBarActivity {
    private int _JugLP;
    private DemoCollectionPagerAdapter mDemoCollectionPagerAdapter;
    private Button _Mas500;
    ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    declarar();
    _Mas500.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            int n = _JugLP + 500;
            mDemoCollectionPagerAdapter.setLP(mViewPager.getCurrentItem(),
                    n);
            mDemoCollectionPagerAdapter.notifyDataSetChanged();
        }
    });
}

@Override
protected void onRestart() {
    // TODO Auto-generated method stub
    super.onRestart();
    declarar();
}

public void declarar() {
    mViewPager = (ViewPager) findViewById(R.id.pager);
    _JugLP = 8000;
    mDemoCollectionPagerAdapter = new DemoCollectionPagerAdapter(
            getSupportFragmentManager(), _JugLP);
    mViewPager.setAdapter(mDemoCollectionPagerAdapter);
    _Mas500 = (Button) findViewById(R.id.btn_mas500);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

public static class DemoCollectionPagerAdapter extends
        FragmentStatePagerAdapter {
    int _LP;
    DemoObjectFragment[] fragments;

    public DemoCollectionPagerAdapter(FragmentManager fm, int n) {
        super(fm);
        _LP = n;
         fragments = new DemoObjectFragment[n];
        Bundle args = new Bundle();
        args.putInt(DemoObjectFragment.ARG_OBJECT, _LP);
        fragments[0].setArguments(args);
        fragments[1].setArguments(args);
    }

    @Override
    public Fragment getItem(int i) {
        return fragments[i];
    }

    public void setLP(int i, int LP) {
        fragments[i].setLP(_LP);
    }

    @Override
    public int getItemPosition(Object object) {
        // TODO Auto-generated method stub
        return POSITION_NONE;
    }

    @Override
    public int getCount() {
        // For this contrived example, we have a 100-object collection.
        return 2;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return "Titulo";
    }
}

/**
 * A dummy fragment representing a section of the app, but that simply
 * displays dummy text.
 */
public static class DemoObjectFragment extends Fragment {

    public static final String ARG_OBJECT = "object";
    private TextView _TxtVwLP;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(
                R.layout.fragment_collection_object, container, false);
        Bundle args = getArguments();
        _TxtVwLP = (TextView) rootView.findViewById(android.R.id.text1);
        _TxtVwLP.setText(Integer.toString(args.getInt(ARG_OBJECT)));
        return rootView;
    }

    public void setLP(int LP) {
        _TxtVwLP.setText(String.valueOf(LP));
    }
}

}

Answer 1

我认为您的问题出在 notifyDataSetChanged 中。因为当您调用 notifyDataSetChanged 时，您会告诉 viewPager 嘿 viewPager 我已为您删除或创建了一些孩子，请重新加载自己。当他重新加载自己时，他会创建片段而没有您已经做出的任何更改。所以我认为你应该改变你的逻辑。

查看以下解决方案： Android FragmentStatePagerAdapter, how to tag a fragment to find it later

Is it possible to access the current Fragment being viewed by a ViewPager?

Answer 2

谢谢mmlooloo！在阅读了您发布的有用文件后，我能够生成答案。这是我更改的内容：

_Mas500.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            int n = _JugLP + 500;
            _JugLP=n;
            DemoObjectFragment x = (DemoObjectFragment) mDemoCollectionPagerAdapter
                    .instantiateItem(mViewPager,
                            mViewPager.getCurrentItem());
            x.setLP(n);
        }
    });

试了几次，textview终于变了！它似乎工作正常，我认为这解决了我现在的问题。谢谢mmlooloo！