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問題描述
限時(shí)送ChatGPT賬號(hào)..
當(dāng)我在 menu1_Fragment.java 的 onCreateView 中放置一個(gè)函數(shù)時(shí)發(fā)生錯(cuò)誤.提前抱歉，因?yàn)槲乙矔?huì)把我的日志放進(jìn)去，所以這可能會(huì)使我的帖子有點(diǎn)大，所以我會(huì)告訴你布局.我很抱歉有很多問題.
Error occurs when I place a function inside onCreateView in menu1_Fragment.java. Sorry in advance as I will be placing my logs in as well so it might make my post a bit big so I will tell you the layout. I am new sorry for the loads of questions.
如果我不將函數(shù) setClick() 放在我的片段中，則代碼可以完美運(yùn)行.快速注意該功能基本上使我在 menu1_layout.xml 中的圖像成為一個(gè) 3 向按鈕，即開始停止重置，當(dāng)您重置時(shí)，它會(huì)彈出一個(gè)準(zhǔn)確時(shí)間的祝酒詞
The code works perfectly if I just don't put the function setClick() inside my fragment. quick note the function basically makes my image in menu1_layout.xml a 3 way button aka start stop reset where when you reset, it pops up a toast of exact time you got
1) menu1_Fragment.java
public class menu1_Fragment extends Fragment {
Chronometer mChronometer;
int loop = 0;
double startTime;
double millis;
View rootview;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootview = inflater.inflate(R.layout.menu1_layout, container, false);
setClick();
return rootview;
}
Button button;
public void setClick() {
mChronometer = (Chronometer) getActivity().findViewById(R.id.aChronometer);
button = (Button) getActivity().findViewById(R.id.stopWatch);
button.setOnClickListener(mStartListener);
button = (Button) getActivity().findViewById(R.id.stopWatch);
button.setOnClickListener(mStartListener);
button = (Button) getActivity().findViewById(R.id.stopWatch);
button.setOnClickListener(mStartListener);
}
View.OnClickListener mStartListener = new View.OnClickListener() {
public void onClick(View v) {
if (loop == 0) {
mChronometer.setBase(SystemClock.elapsedRealtime());
mChronometer.start();
startTime = System.currentTimeMillis();
loop++;
} else if (loop == 1) {
mChronometer.stop();
millis = System.currentTimeMillis()-startTime;
loop++;
} else if (loop == 2) {
mChronometer.setBase(SystemClock.elapsedRealtime());
Context context = getActivity().getApplicationContext();
CharSequence text = "Your Time is: " + (millis/1000);
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
loop = 0;
}
}
};
}
2) 日志
10-28 16:52:26.552 2912-2912/app.z0nen.menu D/AndroidRuntime: Shutting down VM
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: FATAL EXCEPTION: main
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: Process: app.z0nen.menu, PID: 2912
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{app.z0nen.menu/app.z0nen.slidemenu.MyActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.-wrap11(ActivityThread.java)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.os.Looper.loop(Looper.java:148)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5417)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at app.z0nen.slidemenu.menu1_Fragment.setClick(menu1_Fragment.java:39)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at app.z0nen.slidemenu.menu1_Fragment.onCreateView(menu1_Fragment.java:26)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.Fragment.performCreateView(Fragment.java:2220)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:973)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1148)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.BackStackRecord.run(BackStackRecord.java:793)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1535)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.FragmentController.execPendingActions(FragmentController.java:325)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.Activity.performStart(Activity.java:6252)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.-wrap11(ActivityThread.java)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.os.Looper.loop(Looper.java:148)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5417)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)?
10-28 16:52:26.552 2912-2912/app.z0nen.menu E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)?
10-28 16:52:28.662 2912-2912/? I/Process: Sending signal. PID: 2912 SIG: 9
3) MyActivity.Java
public class MyActivity extends Activity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {@link #restoreActionBar()}.
*/
private CharSequence mTitle;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
@Override
public void onNavigationDrawerItemSelected(int position) {
Fragment objFragment = null;
switch (position) {
case 0:
objFragment = new menu1_Fragment();
break;
case 1:
objFragment = new menu2_Fragment();
break;
}
// update the main content by replacing fragments
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container, objFragment)
.commit();
}
public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = getString(R.string.title_section1);
break;
case 2:
mTitle = getString(R.string.title_section2);
break;
}
}
public void restoreActionBar() {
ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
if (!mNavigationDrawerFragment.isDrawerOpen()) {
// Only show items in the action bar relevant to this screen
// if the drawer is not showing. Otherwise, let the drawer
// decide what to show in the action bar.
getMenuInflater().inflate(R.menu.my, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_my, container, false);
return rootView;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MyActivity) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}
4) Menu1_layout.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:gravity="center_horizontal">
<Chronometer
android:id="@+id/aChronometer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="40sp"
android:textColor="#111111"
android:layout_marginTop="27dp"
android:layout_below="@+id/stopWatch"
android:layout_centerHorizontal="true" />
<Button
android:id="@+id/stopWatch"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/stopwatch2"
android:layout_marginTop="38dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
推薦答案
你不能使用 onCreateView() 中的 getActivity() 因?yàn)槠蔚幕顒?dòng)還沒有被尚未創(chuàng)建.在調(diào)用 onActivityCreated() 之前，您不應(yīng)該使用 getActivity()，或者更好的是，使用您膨脹的 rootview 來執(zhí)行您的 findViewByID() 調(diào)用.
You can't use getActivity() from onCreateView() as the fragment's activity has not been created yet. You should use not use getActivity() until onActivityCreated() is called, or better yet, use the rootview you inflated to do your findViewByID() calls.
另外，您正在初始化按鈕 3 次.你應(yīng)該擺脫其中兩個(gè):)
Also, you are initializing your button three times. You should get rid on two of them :)
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