Question

我在FrameActivity中遇到问题，使用FragmentPagerAdapter来声明我的可滑动标签。其中一个选项卡包含Spinner，我想从中收集数据库中的数据。首先，我要发布我的FrameActivity

     public class TranscationMain extends FragmentActivity implements
  ActionBar.TabListener {
Context context;
private ViewPager viewPager;
Spinner spinner_question ;
ContentValues values;                
SQLiteDatabase sql_lite_db_obj; 
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
Cursor cursor;
int i =0;
// Tab titles
private String[] tabs = { "Shipped In", "shipped Out", "New Entry" };

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.transcation_main); 

    AndroidContext.setContext(this);        
    sql_lite_db_obj = DatabaseHelper.getInstance().getDb(); 
    values = new ContentValues();

    // Initilization
    context = this;
    viewPager = (ViewPager) findViewById(R.id.pager);
    actionBar = getActionBar();
    mAdapter = new TabsPagerAdapter(getSupportFragmentManager());  

    viewPager.setAdapter(mAdapter);
    actionBar.setHomeButtonEnabled(false);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);      


    spinner_question = (Spinner)findViewById(R.id.spinner_category);


    // Adding Tabs
    for (String tab_name : tabs) {
        actionBar.addTab(actionBar.newTab().setText(tab_name).setTabListener(this));
    }
    viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

        @Override
        public void onPageSelected(int position) {

            actionBar.setSelectedNavigationItem(position);
        }

        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
        }

        @Override
        public void onPageScrollStateChanged(int arg0) {
        }
    });


}  

@Override
public void onTabReselected(Tab arg0, FragmentTransaction arg1) {
    // TODO Auto-generated method stub

}

@Override
public void onTabSelected(Tab arg0, FragmentTransaction arg1) {
    // TODO Auto-generated method stub
    viewPager.setCurrentItem(arg0.getPosition());

}

@Override
public void onTabUnselected(Tab arg0, FragmentTransaction arg1) {
    // TODO Auto-generated method stub

}
        public void clickHandler(View v)   
{

    if (v.getId() == R.id.btn_new_category_id) {
        // btn click event that define in NewEntry.java calss
                    // click on this button alert dialog will open with editext
                    // from where i insert data in database. which i have to show in 
                     // spinner which define in same activity. Insertion of data is
                   // done successfully. 
    }

}
     private void insertData(String category) {  
    // method to insert data in database
           // working fine
}

现在这是上面代码的异常部分

   private void loadSpinnerData() {  
    DatabaseHelper db = new DatabaseHelper(getApplicationContext());  
    List<String> lables = db.getAllLabels();  
    System.out.println(" data in array : "+lables);

    // Creating adapter for spinner  
    ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item, lables);
    System.out.println(" dapater : "+dataAdapter);

    // Drop down layout style - list view with radio button  
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);  

    // attaching data adapter to spinner  
    spinner_question.setAdapter(dataAdapter);  
}

我想在此块中调用此方法

       if (v.getId() == R.id.btn_new_category_id) {
             loadSpinnerData()
              }

但总是我得到一个NullPointer异常。只是因为

的初始化

        spinner_question = (Spinner)findViewById(R.id.spinner_category);

Spinner未在TranscationMain的布局中定义，它在Fragment

下面定义

        public class NewEntry extends Fragment{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
       spnr = new Spinner(getActivity());
    View rootView = inflater.inflate(R.layout.new_entry, container, false);

    return rootView;
}

}

这就是为什么我在下面的行中获得例外。

   spinner_question.setAdapter(dataAdapter);

现在我不明白我该如何解决这个问题。如何在Fragment中的微调器中绑定数据。我是片段活动的新手。在此先感谢所有

Answer 1

Spinner is not define in above TranscationMain's layout, It define in below Fragment

这就是崩溃的原因。

findViewById在当前膨胀的布局中查找视图。

如果微调器在片段中，则需要在片段中初始化它，然后将数据库中的项目加载到片段中的微调器。

片段

Spinner spinner_question;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {

View rootView = inflater.inflate(R.layout.new_entry, container, false);
spinner_question = (Spinner)rootView.findViewById(R.id.spinner_category);
return rootView;
}

FragmentActivity中的Nullpointer异常，同时在数据库中显示Spinner中的数据

1 个答案: