我在Activity中使用ViewPager
编写代码//mycode
public class ViewPagerActivity extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapterHehe mAdapter1;
private ActionBar actionBar;
// Tab titles
private String[] tabs = {"Feed", "Search", "Status"};
Toast mToast = null;
// set ActionBar;
private LinearLayout layout_btn_search, layout_image_view, layout_edt_search, layout_btn_logout;
private EditText edt_search_1;
String key_word;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_pager);
// check internet cho app
cd = new ConnectionDetector(getApplicationContext());
isInternetPresent = cd.checkMobileInternetConn();
// isOnline
boolean b = isOnline();
if (isOnline()) {
setActionBar();
// Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter1 = new TabsPagerAdapterHehe(getSupportFragmentManager());
viewPager.setAdapter(mAdapter1);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(ViewPagerActivity.this));
}
/**
* on swiping the viewpager make respective tab selected
* */
viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
});
} else {
Toast.makeText(ViewPagerActivity.this, "ネットワーク環境がありません", Toast.LENGTH_SHORT).show();
}
}
// show dialog check Internet cho app
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
hideSoftKeyboard();
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
layout_edt_search.setVisibility(View.GONE);
layout_btn_search.setVisibility(View.VISIBLE);
edt_search_1.setText("");
hideSoftKeyboard();
// on tab selected
// show respected fragment view
boolean b = isOnline();
if (isOnline()) {
viewPager.setCurrentItem(tab.getPosition());
} else {
viewPager.setCurrentItem(tab.getPosition());
Toast.makeText(ViewPagerActivity.this, "ネットワーク環境がありません", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
hideSoftKeyboard();
}
// set ActionBar
private void setActionBar() {
actionBar = getActionBar();
actionBar.setDisplayShowHomeEnabled(false);
actionBar.setDisplayShowTitleEnabled(false);
LayoutInflater inflater = LayoutInflater.from(this);
View mView = inflater.inflate(R.layout.custom_actionbar, null);
edt_search_1.setOnEditorActionListener(new EditText.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
if (actionId == EditorInfo.IME_ACTION_SEARCH) {
// hide keyboard
Bundle b = new Bundle();
key_word = edt_search_1.getText().toString();
b.putString("keyword", keyword);
FragmentSearch fgsearch = new FragmentSearch();
fgsearch.setArguments(b);
Log.e("KEYWORD", key_word);
Toast.makeText(getApplication(), "HEHE", Toast.LENGTH_SHORT).show();
}
return true;
}
return false;
}
});
}
});
actionBar.setCustomView(mView);
actionBar.setDisplayShowCustomEnabled(true);
}
/// do Search
private void doSeachNew() {
}
private class TabsPagerAdapterHehe extends FragmentPagerAdapter {
public TabsPagerAdapterHehe(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int i) {
switch (i) {
case 1:
return new FragmentSearch();
case 2:
return new New_Status();
default:
return new HomeTimelineFragment();
//return new FragmentHomeTimeLine();
}
}
@Override
public int getCount() {
return 3;
}
}
public void hideSoftKeyboard() {
if (getCurrentFocus() != null) {
InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(INPUT_METHOD_SERVICE);
inputMethodManager.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(), 0);
}
}
@Override
public void onBackPressed() {
super.onBackPressed();
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
public static class CheckNetwork {
static String TAG = CheckNetwork.class.getSimpleName();
public static boolean isInternetAvailable(Context context) {
NetworkInfo info = (NetworkInfo) ((ConnectivityManager)
context.getSystemService(Context.CONNECTIVITY_SERVICE)).getActiveNetworkInfo();
if (info == null) {
Log.d(TAG, "no internet connection");
return false;
} else {
if (info.isConnected()) {
Log.d(TAG, " internet connection available...");
return true;
} else {
Log.d(TAG, " internet connection");
return true;
}
}
}
}
}
和我的片段
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_search_list, container, false);
Bundle bundle = this.getArguments();
keyword = bundle.getString("keyword");
Log.e("KeyWord", keyword);
return view;
}
这是我的错误
10-21 14:11:26.639 7278-7278/vn.seesaa.nguyentrunghieu.logintwitter E/SetSizeByPercent﹕ java.lang.NullPointerException
10-21 14:11:26.709 7278-7278/vn.seesaa.nguyentrunghieu.logintwitter E/client﹕ vn.seesaa.nguyentrunghieu.client.TwitterClient@44a626e0
10-21 14:11:26.849 7278-7278/vn.seesaa.nguyentrunghieu.logintwitter E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: vn.seesaa.nguyentrunghieu.logintwitter, PID: 7278
java.lang.NullPointerException
at vn.seesaa.nguyentrunghieu.viewpager.FragmentSearch.onCreateView(FragmentSearch.java:73)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1026)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1207)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1572)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:545)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1106)
at android.support.v4.view.ViewPager.populate(ViewPager.java:952)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474)
at android.view.View.measure(View.java:16628)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16628)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16628)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:16628)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
at android.view.View.measure(View.java:16628)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2298)
at android.view.View.measure(View.java:16628)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1920)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1117)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1299)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5692)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
at android.view.Choreographer.doCallbacks(Choreographer.java:574)
at android.view.Choreographer.doFrame(Choreographer.java:544)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:212)
at android.app.ActivityThread.main(ActivityThread.java:5151)
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:878)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
at dalvik.system.NativeStart.main(Native Method)
请！帮我修复bug !! 非常感谢你！
答案 0 :(得分：0)
在getItem()方法中，您将返回片段的新实例。
return new FragmentSearch();
在这种情况下，没有为片段设置参数。因此调用getArguments()将返回null。因此，nullpointerexception。
在那里做一个空检查。
更新：如果您只是希望异常消失，则以下是修复。如果您关心传递的参数，那么您需要setArguments()在FragmentSearch方法中创建getItem()。
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_search_list, container, false);
Bundle bundle = this.getArguments();
if(bundle != null){
keyword = bundle.getString("keyword");
Log.e("KeyWord", keyword);
}
return view;
}
最佳实践：
始终只使用onCreateView()来扩充布局并将其返回。所有其他代码应放在onActivityCreated()回调中。
答案 1 :(得分：0)
您可能应该更改创建Fragment实例的方案吗？例如，在Android Studio中，如果要创建新的BlankFragment而不使用任何回调但使用片段工厂方法，则会生成以下内容：
/**
* A simple {@link Fragment} subclass.
* Use the {@link BlankFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class BlankFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment BlankFragment.
*/
// TODO: Rename and change types and number of parameters
public static BlankFragment newInstance(String param1, String param2) {
BlankFragment fragment = new BlankFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
public BlankFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_blank, container, false);
}
}
在您的情况下，您的ARG_PARAM1是＆＃34;关键字＆＃34;。一切都是你的需要 - 使用工厂方法创建片段，如下所示：
BlankFragment fragment = BlankFragment.newInstance("hello")
希望这会对你有所帮助。