Question

目前有2个片段，我想现在添加一个，我花了几个小时试图找出如何添加它丢失，这是我的主要活动的代码。

public class SalaatTimesActivity extends AppCompatActivity implements Constants,



  }
}

标签显示但是当我点击第二或第三个标签时它会崩溃。

03-16 21:27:46.203  32749-32749/com.alimuzaffar.ramadanalarm E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.alimuzaffar.ramadanalarm, PID: 32749
    java.lang.NullPointerException
            at com.alimuzaffar.ramadanalarm.widget.FragmentStatePagerAdapter.instantiateItem(FragmentStatePagerAdapter.java:122)
            at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:870)
            at android.support.v4.view.ViewPager.populate(ViewPager.java:1086)
            at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:552)
            at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:514)
            at android.support.v4.view.ViewPager.setCurrentItem(ViewPager.java:495)
            at com.alimuzaffar.ramadanalarm.widget.SlidingTabLayout$TabClickListener.onClick(SlidingTabLayout.java:328)
            at android.view.View.performClick(View.java:4633)
            at android.view.View$PerformClick.run(View.java:19330)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
            at dalvik.system.NativeStart.main(Native Method)

这里是行 FragmentStatePagerAdapter.java:127)

   fragment.setMenuVisibility(false);
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) {
            fragment.setUserVisibleHint(false);
        }
        mFragments.set(position, fragment);
        mCurTransaction.add(container.getId(), fragment);

        return fragment;
    }

frag2.class

     import android.app.Fragment;
import android.hardware.SensorManager;
import android.location.Location;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;


public class fragtwo extends Fragment  {

  Location mLastLocation;
  MapFragment mMapFragment;
  GoogleMap mMap;

  //  private float currentDegree = 0f;
  private SensorManager mSensorManager;

  private float[] mRotationMatrix = new float[16];
  private float[] mValues = new float[3];

  private boolean mRegistered = false;
  private static boolean sWriterExternalPermissionDenied;

  public fragtwo() {
    // Required empty public constructor
  }



  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {

    }
  }



  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
                           Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_two, container, false);


    return view;
  }
}

Answer 1

为什么要添加第3个标签？根据你的适配器代码所说的，如果position == 2你没有项目：这会导致给出一个空项目，因此viewpager可能会崩溃，因为它试图实例化一个null片段。

@Override
public Fragment getItem(int position) {
  switch (position) {
    case 0:

    case 1:
      return mKaabaLocatorFragment = KaabaLocatorFragment.newInstance(mLastLocation);
    case 2:
  }
  return null;
}

将return new fragtwo();添加到案例2，您应该设置。

android卡住片段添加额外的标签

1 个答案: