Android 如何解决；无法暂停活动java.lang.nullpointerexception"；？
我的活动中有4个选项卡，我正在通过滑动来更改它们。所以我使用了4个片段作为标签。刷卡工作正常。但我的问题是，在我的Tab1中，我有一个列表视图，列表视图的每一行都包含两个按钮。因此，点击按钮也能很好地工作。但当我从Tab1滑动到Tab3，再移动到Tab1，然后单击按钮时，它会显示“无法暂停活动java.lang.nullpointerexception”。我不知道发生了什么事。这是我的适配器类代码，我在这里实现了按钮单击。请帮帮我Android 如何解决；无法暂停活动java.lang.nullpointerexception"；？,android,listview,tabs,actionbarsherlock,Android,Listview,Tabs,Actionbarsherlock,我的活动中有4个选项卡，我正在通过滑动来更改它们。所以我使用了4个片段作为标签。刷卡工作正常。但我的问题是，在我的Tab1中，我有一个列表视图，列表视图的每一行都包含两个按钮。因此，点击按钮也能很好地工作。但当我从Tab1滑动到Tab3，再移动到Tab1，然后单击按钮时，它会显示“无法暂停活动java.lang.nullpointerexception”。我不知道发生了什么事。这是我的适配器类代码，我在这里实现了按钮单击。请帮帮我 public class StoreListViewAdapt
public class StoreListViewAdapter extends ArrayAdapter<Item> {
Context context;
private ArrayList<Item> items;
private LayoutInflater layoutInflater;
public StoreListViewAdapter(Context context, int resourceId,
ArrayList<Item> items) {
super(context, resourceId, items);
this.context = context;
this.items = items;
layoutInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
EntryItem entryItem = (EntryItem) item;
final Button buttonView = (Button) view
.findViewById(R.id.button_view);
final Button buttonOffline = (Button) view
.findViewById(R.id.button_offline);
buttonView.setTag(position);
buttonView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(context, ViewButtonActivity.class);
context.startActivity(i);
}
});
}
public class MainActivity extends SherlockFragmentActivity{
private ViewPager viewPager;
private ActionBar actionBar;
Tab tab;
@Override
protected void onCreate(Bundle savedInstanceState) {
setTheme(R.style.ExampleTheme);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
actionBar = getSupportActionBar();
FragmentManager fm = getSupportFragmentManager();
getSupportActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
viewPager = (ViewPager) findViewById(R.id.pager);
ViewPager.SimpleOnPageChangeListener ViewPagerListener = new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
super.onPageSelected(position);
// Find the ViewPager Position
actionBar.setSelectedNavigationItem(position);
}
};
viewPager.setOnPageChangeListener(ViewPagerListener);
// Locate the adapter class called ViewPagerAdapter.java
TabsPagerAdapter viewpageradapter = new TabsPagerAdapter(fm);
// Set the View Pager Adapter into ViewPager
viewPager.setAdapter(viewpageradapter);
ActionBar.TabListener tabListener = new ActionBar.TabListener() {
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// Pass the position on tab click to ViewPager
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
};
// Create first Tab
tab = actionBar.newTab().setText("STORE").setTabListener(tabListener);
actionBar.addTab(tab);
// Create second Tab
tab = actionBar.newTab().setText("NEWS").setTabListener(tabListener);
actionBar.addTab(tab);
// Create third Tab
tab = actionBar.newTab().setText("EVENTS").setTabListener(tabListener);
actionBar.addTab(tab);
// Create fourth Tab
tab = actionBar.newTab().setText("CONTACTUS")
.setTabListener(tabListener);
actionBar.addTab(tab);
}
public class StoreFragment extends SherlockListFragment {
ListView listview;
ArrayList<Item> items = new ArrayList<Item>();
StoreListViewAdapter adapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_store, container,
false);
listview = (ListView) rootView.findViewById(android.R.id.list);
listview.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1,
int position, long arg3) {
}
});
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
items.add(new EntryItem(R.drawable.img1, "Stuff India", "Category:Entertainment",
"View", "Offline","STUFF is the world's biggest gadget and technology lifestyle magazine with more than 25 editions globally. The Indian edition upholds these international values while showcasing the best gadgets and technology available in India."));
items.add(new SectionItem("Previous Issue"));
items.add(new EntryItem(R.drawable.img2, "Medgate Today", "Category:Sports",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img3, "HWM Singapor", "Category:News",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img4, "Shape Singapore", "Category:LifeStyle",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img5, "The Field", "Category:Entertainment",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img1, "TV Times", "Category:News",
"View", "Offline","Detail Description"));
adapter = new StoreListViewAdapter(getActivity(),
R.layout.tab_row_list_entry, items);
listview.setAdapter(adapter);
}
public void onViewButtonClick(View view){
Intent i = new Intent(getActivity(),ViewButtonActivity.class);
startActivity(i);
}
我解决了这个问题@shayan pourvatan帮助我。我正在发布帮助他人的解决方案。实际上，由于ActionBarSherlock兼容库，它给出了错误。解决方法是您的适配器扩展FragmentStatePagerAdapter而不是FragmentPagerAdapter。您可以发布适配器代码吗？我也发布了代码和日志，所以现在请帮助我请尝试更新支持库。。。确保您也使用最新版本的support library.post fragment类
public class StoreFragment extends SherlockListFragment {
ListView listview;
ArrayList<Item> items = new ArrayList<Item>();
StoreListViewAdapter adapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_store, container,
false);
listview = (ListView) rootView.findViewById(android.R.id.list);
listview.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1,
int position, long arg3) {
}
});
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
items.add(new EntryItem(R.drawable.img1, "Stuff India", "Category:Entertainment",
"View", "Offline","STUFF is the world's biggest gadget and technology lifestyle magazine with more than 25 editions globally. The Indian edition upholds these international values while showcasing the best gadgets and technology available in India."));
items.add(new SectionItem("Previous Issue"));
items.add(new EntryItem(R.drawable.img2, "Medgate Today", "Category:Sports",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img3, "HWM Singapor", "Category:News",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img4, "Shape Singapore", "Category:LifeStyle",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img5, "The Field", "Category:Entertainment",
"View", "Offline","Detail Description"));
items.add(new EntryItem(R.drawable.img1, "TV Times", "Category:News",
"View", "Offline","Detail Description"));
adapter = new StoreListViewAdapter(getActivity(),
R.layout.tab_row_list_entry, items);
listview.setAdapter(adapter);
}
public void onViewButtonClick(View view){
Intent i = new Intent(getActivity(),ViewButtonActivity.class);
startActivity(i);
}
06-23 11:45:11.839: E/AndroidRuntime(3520): FATAL EXCEPTION: main
06-23 11:45:11.839: E/AndroidRuntime(3520): java.lang.RuntimeException: Unable to pause activity {com.ebizzinfotech.magazineapp/com.ebizzinfotech.magazineapp.MainActivity}: java.lang.NullPointerException
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2358)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2315)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:2295)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.ActivityThread.access$1700(ActivityThread.java:117)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:942)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.os.Handler.dispatchMessage(Handler.java:99)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.os.Looper.loop(Looper.java:130)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.ActivityThread.main(ActivityThread.java:3687)
06-23 11:45:11.839: E/AndroidRuntime(3520): at java.lang.reflect.Method.invokeNative(Native Method)
06-23 11:45:11.839: E/AndroidRuntime(3520): at java.lang.reflect.Method.invoke(Method.java:507)
06-23 11:45:11.839: E/AndroidRuntime(3520): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
06-23 11:45:11.839: E/AndroidRuntime(3520): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
06-23 11:45:11.839: E/AndroidRuntime(3520): at dalvik.system.NativeStart.main(Native Method)
06-23 11:45:11.839: E/AndroidRuntime(3520): Caused by: java.lang.NullPointerException
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.support.v4.app.FragmentManagerImpl.saveFragmentBasicState(FragmentManager.java:1576)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.support.v4.app.FragmentManagerImpl.saveAllState(FragmentManager.java:1617)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.support.v4.app.FragmentActivity.onSaveInstanceState(FragmentActivity.java:481)
06-23 11:45:11.839: E/AndroidRuntime(3520): at com.actionbarsherlock.app.SherlockFragmentActivity.onSaveInstanceState(SherlockFragmentActivity.java:126)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.Activity.performSaveInstanceState(Activity.java:1037)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.Instrumentation.callActivityOnSaveInstanceState(Instrumentation.java:1181)
06-23 11:45:11.839: E/AndroidRuntime(3520): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2340)
06-23 11:45:11.839: E/AndroidRuntime(3520): ... 12 more