Java Android NullPointerException在CreateView上实例化ViewPager片段时发生，但在键入视图时未发生

我正在尝试用片段填充视图寻呼机，并能够在不同片段之间进行切换。此时，当片段调用onCreateView（）时，试图在TextView中设置文本时会抛出一个NullPointerException，但奇怪的是，如果我捕获到异常，我可以将其切换到所有正确显示的其他片段

注意：第一个和第二个项目不会在ViewPager中呈现，但如果我键入最后一个片段，然后再次返回，它们会正确显示

这是我的片段类：

public class MyFragment extends Fragment {
public static final String EXTRA_MESSAGE = "EXTRA_MESSAGE";

public static LogicController controller;
public static MainActivity activity;

public static final MyFragment newInstance(String message, LogicController controller, MainActivity activity)
{
    MyFragment.activity = activity;
    MyFragment.controller = controller;
    MyFragment f = new MyFragment();
    Bundle bdl = new Bundle(1);
    bdl.putString(EXTRA_MESSAGE, message);
    f.setArguments(bdl);
    return f;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
        Bundle savedInstanceState) {
    try {
        String message = getArguments().getString(EXTRA_MESSAGE);
        //      View v = inflater.inflate(R.layout.myfragment_layout, container, false);
        View v = activity.getLayoutInflater().inflate(R.layout.myfragment_layout, null);

        //      View mainView = pager;

        TextView messageTextView = (TextView)v.findViewById(R.id.testertextView);

        System.out.println(controller.getUpdateGeoNetworkDelay() + messageTextView.getText().toString());



        messageTextView.setText(message);

        return v;


    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}

}

这是我的片段寻呼机适配器：

public class MainPageAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;

public MainPageAdapter(FragmentManager fm, List<Fragment> fragments) {
    super(fm);
    this.fragments = fragments;
}
@Override
public Fragment getItem(int position) {

    Fragment frag = this.fragments.get(position);
    System.out.println("FRAGMENT: " + frag + " pos: " +  position);
    return frag;
}

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

我有理由相信问题是由于没有正确引用textview，但这超出了我的专业水平

日志：

06-24 17:30:44.962: W/System.err(25639): java.lang.NullPointerException
06-24 17:30:44.962: W/System.err(25639):    at com.g.geonet.items.MyFragment.onCreateView(MyFragment.java:48)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
06-24 17:30:44.962: W/System.err(25639):    at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
06-24 17:30:44.962: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.962: W/System.err(25639):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
06-24 17:30:44.962: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.962: W/System.err(25639):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
06-24 17:30:44.962: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.962: W/System.err(25639):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
06-24 17:30:44.962: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.962: W/System.err(25639):    at com.sothree.slidinguppanel.SlidingUpPanelLayout.onMeasure(SlidingUpPanelLayout.java:516)
06-24 17:30:44.962: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:719)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:455)
06-24 17:30:44.962: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.962: W/System.err(25639):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
06-24 17:30:44.962: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.962: W/System.err(25639):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
06-24 17:30:44.962: W/System.err(25639):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
06-24 17:30:44.972: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.972: W/System.err(25639):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
06-24 17:30:44.972: W/System.err(25639):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
06-24 17:30:44.972: W/System.err(25639):    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
06-24 17:30:44.972: W/System.err(25639):    at android.view.View.measure(View.java:16504)
06-24 17:30:44.972: W/System.err(25639):    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1912)
06-24 17:30:44.972: W/System.err(25639):    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
06-24 17:30:44.972: W/System.err(25639):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
06-24 17:30:44.972: W/System.err(25639):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
06-24 17:30:44.972: W/System.err(25639):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
06-24 17:30:44.972: W/System.err(25639):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
06-24 17:30:44.972: W/System.err(25639):    at android.view.Choreographer.doCallbacks(Choreographer.java:574)
06-24 17:30:44.972: W/System.err(25639):    at android.view.Choreographer.doFrame(Choreographer.java:544)
06-24 17:30:44.972: W/System.err(25639):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
06-24 17:30:44.972: W/System.err(25639):    at android.os.Handler.handleCallback(Handler.java:733)
06-24 17:30:44.972: W/System.err(25639):    at android.os.Handler.dispatchMessage(Handler.java:95)
06-24 17:30:44.972: W/System.err(25639):    at android.os.Looper.loop(Looper.java:136)
06-24 17:30:44.972: W/System.err(25639):    at android.app.ActivityThread.main(ActivityThread.java:5001)
06-24 17:30:44.972: W/System.err(25639):    at java.lang.reflect.Method.invokeNative(Native Method)
06-24 17:30:44.972: W/System.err(25639):    at java.lang.reflect.Method.invoke(Method.java:515)
06-24 17:30:44.972: W/System.err(25639):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
06-24 17:30:44.972: W/System.err(25639):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
06-24 17:30:44.972: W/System.err(25639):    at dalvik.system.NativeStart.main(Native Method)

---

谢谢你的帮助

请检查此行：

System.out.println(controller.getUpdateGeoNetworkDelay() + messageTextView.getText().toString());
    messageTextView.setText(message);

我猜message是从newInstance传递的包中参数的内容，所以应该是这样的：

    messageTextView.setText(getArguments().getStringExtra(EXTRA_MESSAGE,"Message not passed"));

---

此外，此行中的最后一个修饰符public static final MyFragment newInstance似乎不合适，因此请将其删除。

啊，是的，就是它！我讨厌这么简单的事情，哈哈。干杯

    messageTextView.setText(getArguments().getStringExtra(EXTRA_MESSAGE,"Message not passed"));