我有一个 ViewPager，它包含三个 fragment (在选项卡式布局内)。第三个也是最后一个 fragment 包含两个 ImageButtons(向上和向下箭头)和一个 ImageView，该 ImageView 根据点击的方向箭头循环显示不同的图像。到目前为止，我无法使 ImageButton 上的 onClick 方法起作用。
据我所知，如果我在 Fragment 的 XML 中使用 onClick，代码首先会在父 Activity 的源代码中查找 onClick 方法。因此，我尝试根据 StackOverflow 上类似问题的现有解决方案定义 onClick 监听器，但这种方法似乎不起作用。我做错了什么还是完全有另一个错误？
这是 fragment 的 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:orientation="vertical"
android:background="#2E2E2E" >
<ImageButton
android:id="@+id/pageUpButton"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:layout_gravity="center"
android:src="@drawable/uparrow"
android:layout_marginTop="5dp"
android:contentDescription="@string/contentDesc"
android:background="@drawable/arrow_imagebutton_selector" />
<ImageView
android:id="@+id/recipeDirectionsImage"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="10"
android:contentDescription="@string/contentDesc" />
<ImageButton
android:id="@+id/pageDownButton"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:layout_gravity="center"
android:src="@drawable/downarrow"
android:contentDescription="@string/contentDesc"
android:background="@drawable/arrow_imagebutton_selector" />
<!-- make list recipePagesList -->
</LinearLayout>
Fragment的java代码: 注意:我仅展示了此代码中其中一个按钮的使用 注:pageUp和pageDown分别是上一页和下一页。
public class RecipeDirectionsFragment extends Fragment //implements OnClickListener
{
int REQUEST_CODE = 0, RESULT_OK = 1, page_num = 1;
public ImageView recipePage;
// private ImageButton pageButton = null;
private ImageButton upPageButton = null;
private ImageButton downPageButton = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View rootView = inflater.inflate(R.layout.fragment_recipe_directions, container, false);
recipePage = (ImageView) rootView.findViewById(R.id.recipeDirectionsImage);
changePage();
upPageButton = (ImageButton)rootView.findViewById(R.id.upButton);
downPageButton = (ImageButton)rootView.findViewById(R.id.downButton);
// pageButton = (ImageButton)rootView.findViewById(R.id.upButton);
// pageButton.setOnClickListener(this);
upPageButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
pageUp(v);
}
});
downPageButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
pageDown(v);
}
});
return rootView;
}
public void changePage()
{
//recipePage = (ImageView) getView().findViewById(R.id.recipeDirectionsImage);
switch(page_num)
{
case 1: recipePage.setImageResource(R.drawable.recipe_1_3); break;
case 2: recipePage.setImageResource(R.drawable.recipe_1_4); break;
case 3: recipePage.setImageResource(R.drawable.recipe_1_5); break;
case 4: recipePage.setImageResource(R.drawable.recipe_1_6); break;
case 5: recipePage.setImageResource(R.drawable.recipe_1_7); break;
case 6: recipePage.setImageResource(R.drawable.recipe_1_8); break;
}
}
public void pageUp(View view)
{
//Toast.makeText(getActivity(), "up", Toast.LENGTH_SHORT).show();
page_num = (page_num > 1) ? page_num-1 : 1;
changePage();
}
public void pageDown(View view)
{
//Toast.makeText(getActivity(), "down", Toast.LENGTH_SHORT).show();
page_num = (page_num < 6) ? page_num+1 : 6;
changePage();
}
}
使用上面的代码，每次我切换到这个 fragment 时，应用程序都会崩溃。它甚至没有显示我加载 fragment 。
我什至尝试使用这个替代的重写 onClick 函数并使该类实现 onClickListener :
@Override
public void onClick(View v)
{
switch (v.getId())
{
case R.id.upButton: Toast.makeText(getActivity(), "up", Toast.LENGTH_SHORT).show();
break;
case R.id.downButton: Toast.makeText(getActivity(), "down", Toast.LENGTH_SHORT).show();
break;
}
}
这也不起作用并且会使应用程序崩溃。
我遇到的另一个解决方案建议在 Activity 中使用 paeUp 和 pageDown 函数，但我需要使用变量 page_num 并且不知道如何使用某种 FragmentManager 在 Activity 中访问它。另外，我宁愿将函数保留在 fragment 中，并遵循问题前面显示的方法。
我正在使用 API 21，不知道这是否有任何区别。
编辑
fragment 加载失败时的 Logcat 输出 fragment (给出对话“不幸的是 {appname} 已停止”并回滚到上一个 Activity )
03-12 21:29:19.965: D/AndroidRuntime(25773): Calling main entry com.android.commands.am.Am
03-12 21:29:19.970: I/ActivityManager(546): START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.culami/.WelcomePageActivity} from uid 2000 on display 0
03-12 21:29:19.974: D/AndroidRuntime(25773): Shutting down VM
03-12 21:29:19.977: I/art(25773): Debugger is no longer active
03-12 21:29:19.985: E/art(25773): Thread attaching while runtime is shutting down: Binder_2
03-12 21:29:19.985: I/AndroidRuntime(25773): NOTE: attach of thread 'Binder_2' failed
03-12 21:29:20.017: I/ActivityManager(546): Start proc com.example.culami for activity com.example.culami/.WelcomePageActivity: pid=25791 uid=10088 gids={50088, 9997, 3003} abi=armeabi-v7a
03-12 21:29:20.054: I/art(25791): Late-enabling -Xcheck:jni
03-12 21:29:20.282: D/OpenGLRenderer(25791): Render dirty regions requested: true
03-12 21:29:20.290: D/Atlas(25791): Validating map...
03-12 21:29:20.343: I/Adreno-EGL(25791): <qeglDrvAPI_eglInitialize:410>: QUALCOMM Build: 10/28/14, c33033c, Ia6306ec328
03-12 21:29:20.344: I/OpenGLRenderer(25791): Initialized EGL, version 1.4
03-12 21:29:20.363: D/OpenGLRenderer(25791): Enabling debug mode 0
03-12 21:29:20.507: I/ActivityManager(546): Displayed com.example.culami/.WelcomePageActivity: +527ms
03-12 21:29:20.874: I/MicrophoneInputStream(1077): mic_close com.google.android.speech.audio.w@3d6762c
03-12 21:29:20.916: D/audio_hw_primary(182): disable_audio_route: reset and update mixer path: audio-record
03-12 21:29:20.916: D/audio_hw_primary(182): disable_snd_device: snd_device(36: voice-rec-mic)
03-12 21:29:20.923: I/HotwordRecognitionRnr(1077): Hotword detection finished
03-12 21:29:20.926: I/HotwordRecognitionRnr(1077): Stopping hotword detection.
03-12 21:29:21.733: I/ActivityManager(546): START u0 {cmp=com.example.culami/.UserDashboardActivity} from uid 10088 on display 0
03-12 21:29:21.741: D/audio_hw_primary(182): select_devices: out_snd_device(2: speaker) in_snd_device(0: none)
03-12 21:29:21.741: D/ACDB-LOADER(182): ACDB -> send_afe_cal
03-12 21:29:21.741: D/audio_hw_primary(182): enable_snd_device: snd_device(2: speaker)
03-12 21:29:21.744: D/audio_hw_primary(182): enable_audio_route: apply and update mixer path: low-latency-playback
03-12 21:29:21.926: I/ActivityManager(546): Displayed com.example.culami/.UserDashboardActivity: +188ms
03-12 21:29:22.592: I/ActivityManager(546): START u0 {cmp=com.example.culami/.RecipeDashboardActivity} from uid 10088 on display 0
03-12 21:29:22.914: I/ActivityManager(546): Displayed com.example.culami/.RecipeDashboardActivity: +313ms
03-12 21:29:23.732: I/ActivityManager(546): START u0 {cmp=com.example.culami/.ActiveRecipeActivity} from uid 10088 on display 0
03-12 21:29:24.128: I/ActivityManager(546): Displayed com.example.culami/.ActiveRecipeActivity: +376ms
03-12 21:29:25.487: D/AndroidRuntime(25791): Shutting down VM
03-12 21:29:25.488: E/AndroidRuntime(25791): FATAL EXCEPTION: main
03-12 21:29:25.488: E/AndroidRuntime(25791): Process: com.example.culami, PID: 25791
03-12 21:29:25.488: E/AndroidRuntime(25791): java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
03-12 21:29:25.488: E/AndroidRuntime(25791): at com.example.culami.RecipeDirectionsFragment.onCreateView(RecipeDirectionsFragment.java:39)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:486)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.view.ViewPager.populate(ViewPager.java:919)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.support.v4.view.ViewPager$3.run(ViewPager.java:249)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.view.Choreographer.doCallbacks(Choreographer.java:580)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.view.Choreographer.doFrame(Choreographer.java:549)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.os.Handler.handleCallback(Handler.java:739)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.os.Handler.dispatchMessage(Handler.java:95)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.os.Looper.loop(Looper.java:135)
03-12 21:29:25.488: E/AndroidRuntime(25791): at android.app.ActivityThread.main(ActivityThread.java:5221)
03-12 21:29:25.488: E/AndroidRuntime(25791): at java.lang.reflect.Method.invoke(Native Method)
03-12 21:29:25.488: E/AndroidRuntime(25791): at java.lang.reflect.Method.invoke(Method.java:372)
03-12 21:29:25.488: E/AndroidRuntime(25791): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
03-12 21:29:25.488: E/AndroidRuntime(25791): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
03-12 21:29:25.489: W/ActivityManager(546): Force finishing activity com.example.culami/.ActiveRecipeActivity
03-12 21:29:25.538: I/OpenGLRenderer(546): Initialized EGL, version 1.4
03-12 21:29:25.992: W/ActivityManager(546): Activity pause timeout for ActivityRecord{128c44a3 u0 com.example.culami/.ActiveRecipeActivity t502 f}
03-12 21:29:26.887: D/audio_hw_primary(182): disable_audio_route: reset and update mixer path: low-latency-playback
03-12 21:29:26.887: D/audio_hw_primary(182): disable_snd_device: snd_device(2: speaker)
03-12 21:29:27.052: E/(180): invalid crash request of size 4 (from pid=25647 uid=0)
03-12 21:29:27.153: W/qcom_sensors_hal(546): hal_sensor1_data_cb: SENSOR1_MSG_TYPE_BROKEN_PIPE
03-12 21:29:27.160: E/Diag_Lib(25866): Diag_LSM_Init: Failed to open handle to diag driver, error = 2
03-12 21:29:27.160: E/Sensors(25866): sns_fsa_la.c(386):fsa: fflush failed, 9
03-12 21:29:27.161: E/Sensors(25866): sns_fsa_la.c(386):fsa: fflush failed, 9
03-12 21:29:27.186: W/Sensors(25866): sns_smr_la.c(446):smr_la: smr_apps_la_thread_main is starting, fd=11, sns_smr.en_rx_msg_ptr=b6f7e9d0
03-12 21:29:27.196: W/Sensors(25866): sns_sam_app.c(6827):sns_sam_reg_algo: Registering algo service 16, err 0
03-12 21:29:27.204: E/Sensors(25866): sns_debug_main.c(565):Debug Config File missing in EFS!
03-12 21:29:27.250: I/Process(25791): Sending signal. PID: 25791 SIG: 9
03-12 21:29:27.265: D/audio_hw_primary(182): select_devices: out_snd_device(2: speaker) in_snd_device(0: none)
03-12 21:29:27.265: D/ACDB-LOADER(182): ACDB -> send_afe_cal
03-12 21:29:27.265: D/audio_hw_primary(182): enable_snd_device: snd_device(2: speaker)
03-12 21:29:27.268: D/audio_hw_primary(182): enable_audio_route: apply and update mixer path: low-latency-playback
03-12 21:29:27.292: I/WindowState(546): WIN DEATH: Window{b7fc8b3 u0 com.example.culami/com.example.culami.UserDashboardActivity}
03-12 21:29:27.300: I/WindowState(546): WIN DEATH: Window{4829921 u0 com.example.culami/com.example.culami.RecipeDashboardActivity}
03-12 21:29:27.304: W/InputDispatcher(546): channel '2e2367ca com.example.culami/com.example.culami.WelcomePageActivity (server)' ~ Consumer closed input channel or an error occurred. events=0x9
03-12 21:29:27.304: E/InputDispatcher(546): channel '2e2367ca com.example.culami/com.example.culami.WelcomePageActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
03-12 21:29:27.304: W/InputDispatcher(546): channel 'd9487ff com.example.culami/com.example.culami.ActiveRecipeActivity (server)' ~ Consumer closed input channel or an error occurred. events=0x9
03-12 21:29:27.304: E/InputDispatcher(546): channel 'd9487ff com.example.culami/com.example.culami.ActiveRecipeActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
03-12 21:29:27.308: I/WindowState(546): WIN DEATH: Window{d9487ff u0 com.example.culami/com.example.culami.ActiveRecipeActivity}
03-12 21:29:27.308: W/InputDispatcher(546): Attempted to unregister already unregistered input channel 'd9487ff com.example.culami/com.example.culami.ActiveRecipeActivity (server)'
03-12 21:29:27.313: I/WindowState(546): WIN DEATH: Window{2e2367ca u0 com.example.culami/com.example.culami.WelcomePageActivity}
03-12 21:29:27.313: W/InputDispatcher(546): Attempted to unregister already unregistered input channel '2e2367ca com.example.culami/com.example.culami.WelcomePageActivity (server)'
03-12 21:29:27.423: I/ActivityManager(546): Process com.example.culami (pid 25791) has died
03-12 21:29:27.460: I/ActivityManager(546): Start proc com.example.culami for activity com.example.culami/.RecipeDashboardActivity: pid=25875 uid=10088 gids={50088, 9997, 3003} abi=armeabi-v7a
03-12 21:29:27.545: I/art(25875): Late-enabling -Xcheck:jni
03-12 21:29:27.816: D/OpenGLRenderer(25875): Render dirty regions requested: true
03-12 21:29:27.822: D/Atlas(25875): Validating map...
03-12 21:29:27.848: I/Adreno-EGL(25875): <qeglDrvAPI_eglInitialize:410>: QUALCOMM Build: 10/28/14, c33033c, Ia6306ec328
03-12 21:29:27.849: I/OpenGLRenderer(25875): Initialized EGL, version 1.4
03-12 21:29:27.866: D/OpenGLRenderer(25875): Enabling debug mode 0
03-12 21:29:28.002: W/InputMethodManagerService(546): Got RemoteException sending setActive(false) notification to pid 25791 uid 10088
03-12 21:29:28.013: I/ActivityManager(546): Displayed com.example.culami/.RecipeDashboardActivity: +587ms
: E/(): Device disconnected: 1
: E/(): Device disconnected
最佳答案
您没有找到正确名称的 ViewById。据我所知，您正在使用差异名称来夸大图像按钮，但发现差异/错误的名称。
pageDownButton is realId and u are using downButton
它可能会解决你的问题。
关于java - 无法使用现有解决方案使 Fragment 中的 onClick 方法正常工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29021441/