在android片段上初始化Int和String值

时间：2014-08-28 06:46:42

标签： android android-fragments textview initialization

我希望你们能帮助我。如何正确初始化片段上的值？我可以使用下面的语法用我的数据库中的值初始化int和string吗？ 

public class AccountFragment extends Fragment {
private LoginDataBaseAdapter loginDataBaseAdapter;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
     // create a instance of SQLite Database
    loginDataBaseAdapter = new LoginDataBaseAdapter(getActivity());
     loginDataBaseAdapter=loginDataBaseAdapter.open();

    View rootView = inflater.inflate(R.layout.fragment_account, container, false);

        TextView a = (TextView) rootView.findViewById(R.id.secsummview);
        a.setText(secRows);

        TextView b = (TextView) rootView.findViewById(R.id.studsummview);
        b.setText(subRows);

        TextView c = (TextView) rootView.findViewById(R.id.subsummview);
        c.setText(unitSum);

        TextView d = (TextView) rootView.findViewById(R.id.nameview);
        d.setText(name);
    return rootView;



}

    int secRows = loginDataBaseAdapter.countsecRows();
    int subRows = loginDataBaseAdapter.countsubRows();
    int unitSum = loginDataBaseAdapter.countunitsSum();
    String name=loginDataBaseAdapter.getUsername();

}

我尝试在下面，上面甚至是oncreate中初始化这些值，但它不起作用。这是logcat：

    08-28 14:40:59.184: E/AndroidRuntime(29974): FATAL EXCEPTION: main
08-28 14:40:59.184: E/AndroidRuntime(29974): java.lang.NullPointerException
08-28 14:40:59.184: E/AndroidRuntime(29974):    at com.csu.eclassrecord.AccountFragment.<init>(AccountFragment.java:41)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at com.eclassrecord.tabsswipe.adapter.TabsPagerAdapter.getItem(TabsPagerAdapter.java:22)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:97)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:832)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.support.v4.view.ViewPager.populate(ViewPager.java:982)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.View.measure(View.java:15609)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4916)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.View.measure(View.java:15609)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:850)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.View.measure(View.java:15609)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4916)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2221)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.View.measure(View.java:15609)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2165)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1249)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1443)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1139)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4906)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:776)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.Choreographer.doCallbacks(Choreographer.java:579)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.Choreographer.doFrame(Choreographer.java:548)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.os.Handler.handleCallback(Handler.java:725)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.os.Handler.dispatchMessage(Handler.java:92)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.os.Looper.loop(Looper.java:153)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at android.app.ActivityThread.main(ActivityThread.java:5331)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at java.lang.reflect.Method.invokeNative(Native Method)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at java.lang.reflect.Method.invoke(Method.java:511)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
08-28 14:40:59.184: E/AndroidRuntime(29974):    at dalvik.system.NativeStart.main(Native Method)

我是Android开发的新手，我们将不胜感激。提前谢谢。

2 个答案:

答案 0 :(得分：2)

您正在尝试访问未初始化的变量。试试这个

    public class AccountFragment extends Fragment {
    private LoginDataBaseAdapter loginDataBaseAdapter;


        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
             // create a instance of SQLite Database
            loginDataBaseAdapter = new LoginDataBaseAdapter(getActivity());
             loginDataBaseAdapter=loginDataBaseAdapter.open();
          //intialize variables
           int secRows = loginDataBaseAdapter.countsecRows();
            int subRows = loginDataBaseAdapter.countsubRows();
            int unitSum = loginDataBaseAdapter.countunitsSum();
            String name=loginDataBaseAdapter.getUsername();

            View rootView = inflater.inflate(R.layout.fragment_account, container, false);

                TextView a = (TextView) rootView.findViewById(R.id.secsummview);
                a.setText(secRows); //might have to cast as String like. String.valueOf(secRows);


                TextView b = (TextView) rootView.findViewById(R.id.studsummview);
                b.setText(subRows);

                TextView c = (TextView) rootView.findViewById(R.id.subsummview);
                c.setText(unitSum);

                TextView d = (TextView) rootView.findViewById(R.id.nameview);
                d.setText(name);
            return rootView;



        }



        }

答案 1 :(得分：2)

public class AccountFragment extends Fragment {
private LoginDataBaseAdapter loginDataBaseAdapter;
int secRows;
int subRows;
int unitSum;
String name;

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

    View rootView = inflater.inflate(R.layout.fragment_account, container,
            false);

    return rootView;
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    // create a instance of SQLite Database
    loginDataBaseAdapter = new LoginDataBaseAdapter(getActivity());
    loginDataBaseAdapter = loginDataBaseAdapter.open();

    secRows = loginDataBaseAdapter.countsecRows();
    subRows = loginDataBaseAdapter.countsubRows();
    unitSum = loginDataBaseAdapter.countunitsSum();

    name = loginDataBaseAdapter.getUsername();

    View rootView = getView();
    TextView a = (TextView) rootView.findViewById(R.id.secsummview);
    a.setText(secRows);

    TextView b = (TextView) rootView.findViewById(R.id.studsummview);
    b.setText(subRows);

    TextView c = (TextView) rootView.findViewById(R.id.subsummview);
    c.setText(unitSum);

    TextView d = (TextView) rootView.findViewById(R.id.nameview);
    d.setText(name);
}

}

相关问题
最新问题