因此，只有当viewpager使用Activity时，我才会遇到更多片段问题。 ：|
我的问题在于实现启动日历应用程序的代码。当然我有一个链接到代码的按钮，当点击它启动日历应用程序的按钮时。我使用下面的代码 -
// Calendar Launch
Button calendar_launch = (Button) getView().findViewById(R.id.calendar_launch);
date_launch.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
PackageManager packageManager = getActivity().getPackageManager();
Intent intent_calendar = new Intent(Intent.ACTION_MAIN).addCategory(Intent.CATEGORY_LAUNCHER);
// Verify calendar implementation
String clockImpls[][] = {
{"Default", "com.android.calendar", "com.android.calendar.AllInOneActivity" },
{"HTC", "com.htc.calendar", "com.htc.calendar.LaunchActivity"},
{"GOOGLE", "com.google.android.calendar", "com.android.calendar.AllInOneActivity"},
{"SAMSUNG", "ShiftCalendar.SamsungElectronics","ShiftCalendar.SamsungElectronics.main"}
};
boolean foundClockImpl = false;
for(int i=0; i<clockImpls.length; i++) {
String vendor = clockImpls[i][0];
String packageName = clockImpls[i][1];
String className = clockImpls[i][2];
try {
ComponentName cn = new ComponentName(packageName, className);
ActivityInfo aInfo = packageManager.getActivityInfo(cn, PackageManager.GET_META_DATA);
intent_calendar.setComponent(cn);
//debug("Found " + vendor + " --> " + packageName + "/" + className);
foundClockImpl = true;
} catch (NameNotFoundException e) {
//debug(vendor + " does not exists");
}
}
if (foundClockImpl) {
startActivity(intent_calendar);
}
}
});
但是在启动应用程序后，它立即关闭，在检查错误日志后我浏览了网页以获得适当的答案，但我真的不知道我要搜索什么？查看错误日志，它表示错误（NullPointerException）存在于以下行中 - Button date_launch = (Button) getView().findViewById(R.id.calendar_launch);
我该如何解决这个错误，还有什么在实现代码从man活动到片段时还需要知道什么？
类（片段）
public class HomeFragment extends Fragment {
public static HomeFragment newInstance(String title) {
HomeFragment homeFragment = new HomeFragment();
Bundle bundle = new Bundle();
bundle.putString("title", title);
homeFragment.setArguments(bundle);
return homeFragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_activity_home, container, false);
// (Calendar) Date function - Displays dateview on Card
final boolean keepRunning1 = true;
Thread thread_two = new Thread(){
@Override
public void run(){
while(keepRunning1){
// Make the thread wait half a second. If you want...
try {
Thread.sleep(500);
} catch (InterruptedException e) {
Toast.makeText(getActivity().getApplicationContext(), "Default Signature Fail", Toast.LENGTH_LONG).show();
e.printStackTrace();
}
getActivity().runOnUiThread(new Runnable(){
@Override
public void run(){
TextView date = (TextView) getView().findViewById(R.id.date);
date.setText(DateUtils.formatDateTime(getActivity().getBaseContext(), System.currentTimeMillis(),DateUtils.FORMAT_SHOW_WEEKDAY | DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_SHOW_YEAR));
}
});
}
}
};
thread_two.start();
// Calendar Launch
Button calendar_launch = (Button) getView().findViewById(R.id.calendar_launch);
date_launch.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
PackageManager packageManager = getActivity().getPackageManager();
Intent intent_calendar = new Intent(Intent.ACTION_MAIN).addCategory(Intent.CATEGORY_LAUNCHER);
// Verify calendar implementation
String clockImpls[][] = {
{"Default", "com.android.calendar", "com.android.calendar.AllInOneActivity" },
{"HTC", "com.htc.calendar", "com.htc.calendar.LaunchActivity"},
{"GOOGLE", "com.google.android.calendar", "com.android.calendar.AllInOneActivity"},
{"SAMSUNG", "ShiftCalendar.SamsungElectronics","ShiftCalendar.SamsungElectronics.main"}
};
boolean foundClockImpl = false;
for(int i=0; i<clockImpls.length; i++) {
String vendor = clockImpls[i][0];
String packageName = clockImpls[i][1];
String className = clockImpls[i][2];
try {
ComponentName cn = new ComponentName(packageName, className);
ActivityInfo aInfo = packageManager.getActivityInfo(cn, PackageManager.GET_META_DATA);
intent_calendar.setComponent(cn);
//debug("Found " + vendor + " --> " + packageName + "/" + className);
foundClockImpl = true;
} catch (NameNotFoundException e) {
//debug(vendor + " does not exists");
}
}
if (foundClockImpl) {
startActivity(intent_calendar);
}
}
});
return view;
}
}
layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/blue"
android:layoutAnimation="@anim/default_anim_parse"
android:orientation="vertical" >
<!-- Header -->
<LinearLayout
android:id="@+id/header_image"
android:layout_width="match_parent"
android:layout_height="120dp"
android:background="@drawable/header"
android:orientation="vertical" >
<RelativeLayout
android:id="@+id/google_search"
android:layout_width="match_parent"
android:layout_height="42dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="40dp"
android:background="@drawable/mybutton"
android:orientation="vertical" >
<com.activelauncher.MyTextView
android:id="@+id/search_text"
android:layout_width="100dp"
android:layout_height="42dp"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="10dp"
android:gravity="center|left"
android:text="Google Search"
android:textColor="#6b6b6b"
android:textSize="15.5sp" />
<Button
android:id="@+id/search_button"
android:layout_width="35dp"
android:layout_height="35dp"
android:layout_alignParentRight="true"
android:layout_marginRight="4dp"
android:layout_marginTop="4dp"
android:gravity="center|left"
android:background="@drawable/google_search_button" />
</RelativeLayout>
</LinearLayout>
<!-- Header End -->
<!-- Date View -->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="70dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="10dp"
android:background="@drawable/bg_card"
android:orientation="vertical" >
<com.activelauncher.MyTextView
android:id="@+id/date"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:drawableRight="@drawable/ic_action_event_normal"
android:gravity="left"
android:text="@string/calendar"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#6b6b6b"
android:textSize="20sp" />
<com.activelauncher.MyTextView
android:id="@+id/date_two"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="left"
android:text="@string/calendar_summary"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#6b6b6b"
android:textSize="15sp" />
</LinearLayout>
<!-- Date View End -->
<!-- Date Button -->
<Button
android:id="@+id/calendar_launch"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:background="@drawable/mybutton"
android:drawableLeft="@drawable/ic_action_browse_normal"
android:gravity="left|center"
android:paddingLeft="5dp"
android:text="@string/calendar_button"
android:textColor="#4285F4" />
<!-- Date Button End -->
<!-- Time View -->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="70dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="10dp"
android:background="@drawable/bg_card"
android:orientation="vertical" >
<com.activelauncher.MyTextView
android:id="@+id/time"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:drawableRight="@drawable/ic_action_alarm_normal"
android:gravity="left"
android:text="@string/time"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#6b6b6b"
android:textSize="20sp" />
<com.activelauncher.MyTextView
android:id="@+id/time_two"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="left"
android:text="@string/time_summary"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#6b6b6b"
android:textSize="15sp" />
</LinearLayout>
<!-- Time Button -->
<Button
android:id="@+id/time_launch"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:background="@drawable/mybutton"
android:drawableLeft="@drawable/ic_action_browse_normal"
android:gravity="left|center"
android:paddingLeft="5dp"
android:text="@string/time_button"
android:textColor="#4285F4" />
<!-- Time View End -->
</LinearLayout>
答案 0 :(得分：1)
试试这种方式
Button date_launch = (Button) view.findViewById(R.id.calendar_launch);
而不是
Button calendar_launch = (Button) getView().findViewById(R.id.calendar_launch);
您必须在Button onCreateView(....)中Fragement初始化您View，inflated {{1}}