ViewPager findViewById错误NullPointerException

最新推荐文章于 2021-01-26 11:01:08 发布
原创 最新推荐文章于 2021-01-26 11:01:08 发布 · 779 阅读 · 0 ·
CC 4.0 BY-SA版权
版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。

在Fragment工程中，详细探讨了initViewPager方法在onActivityCreated阶段而非onCreateView阶段调用时遇到的NullPointerException问题，并提供了针对性解决方案。

摘要生成于 C知道 ，由 DeepSeek-R1 满血版支持， 前往体验 >

advPager = (ViewPager) getView().findViewById(R.id.adv_pager);
08-07 12:51:16.041: E/AndroidRuntime(29103): Caused by: java.lang.NullPointerException



Fragment工程中，initViewPager在onActivityCreated初始调用，而不是onCreateView。



ViewPager的用法(3)——ViewPager嵌套Fragment
阿方的博客
03-14 4145
1、ViewPager嵌套Fragment的重点 (1)Activity继承了V4包下的FragmentActivity (2)数据源中的List   变成了List              初始化数据源的时候需要将数据使用fragment.setArguments(bundle)传入fragment中 (3)V4包下在Activity中获取FragmentManager时需要使用
Android基于ViewPager2实现循环轮播图、3D画廊效果
weixin_42046829的博客
07-28 6127
一、前言 在开发中经常会遇到循环轮播图，之前的实现方式是在Activity中使用定时器控制轮播。后面想了想，看能不能把ViewPager2和定时器封装成自定义控件方便移植。然后就有了这个自定义控件。 二、控件实现 因为使用的是ViewPager2，所以要用到适配器，这里写了个BaseBannerAdapter用来设置循环滚动 /** * @ Author : 廖健鹏 * @ Date : 2021/7/27 * @ e-mail : 329524627@qq.com * @ Description
ViewPager中用findViewById得不到View___findViewById应用注意事项
phenixyf的专栏
05-06 2631
ViewPager的主要功能是使视图左右滑动 1.在布局文件中加入组件 android.support.v4.view.ViewPager android:id="@+id/heroPager" android:layout_width="fill_parent" android:layout_height="wrap_content"/> 和android的其
Fragment与ViewPager之findViewById()报错
MonochromeContrast的博客
10-21 1140
与ViewPager有关的碎片中findViewById()方法报错
自定义控件实例化后报空指针异常 java.lang.NullPointerException
烧烤电影香烟和啤酒
01-26 2330
自定义控件 findViewById()实例化后报空指针异常，原因是可能是在主布局中使用了子布局。 findViewById()方法的原本的形态是 view.findViewById()，这个 view 是经过 setContentView() 方法设置的 layout 文件，所以 id 查找范围是当前的 Activity。 当在一些主布局的子布局中，需要用 view.findViewById() 才行，要不然就会报空指针错误。 因此在调用时，添加布局名，形式如下：addLayout.findV...
android ViewPager案例
写博客只为学习
04-11 220
ViewPager和PagerAdapter package com.example.mainframework02; import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.os.Bundle; import android.support.
Android ViewPager实现QQ界面切换效果详解
mViewPager = findViewById(R.id.mViewPager); mViewPager.setAdapter(new MyPagerAdapter(getSupportFragmentManager(), fragments)); } } ``` 然而，有时候在数据更新后调用PagerAdapter的`...
怎么解决错误PROCESS ENDED (18378) for package com.example.app2526 ---------------------------- 2025-05-27 18:30:22.636 348-1216 BufferQueueProducer surfaceflinger E [SurfaceView - com.example.app2526/com.example.app2526.MainActivity#0](id:15c00000522,api:3,p:432,c:348) cancelBuffer: BufferQueue has been abandoned 2025-05-27 18:30:22.670 348-1216 BufferQueueProducer surfaceflinger E [SurfaceView - com.example.app2526/com.example.app2526.MainActivity#0](id:15c00000522,api:3,p:432,c:348) connect: BufferQueue has been abandoned ---------------------------- PROCESS STARTED (18536) for package com.example.app2526 ---------------------------- 2025-05-27 18:30:25.230 18536-18536 NetworkSecurityConfig com.example.app2526 D No Network Security Config specified, using platform default 2025-05-27 18:30:25.230 18536-18536 NetworkSecurityConfig com.example.app2526 D No Network Security Config specified, using platform default 2025-05-27 18:30:25.310 18536-18561 libEGL com.example.app2526 D loaded /vendor/lib/egl/libEGL_emulation.so 2025-05-27 18:30:25.312 18536-18561 libEGL com.example.app2526 D loaded /vendor/lib/egl/libGLESv1_CM_emulation.so 2025-05-27 18:30:25.316 18536-18561 libEGL com.example.app2526 D loaded /vendor/lib/egl/libGLESv2_emulation.so 2025-05-27 18:30:25.334 18536-18536 AppCompatDelegate com.example.app2526 D Checking for metadata for AppLocalesMetadataHolderService : Service not found 2025-05-27 18:30:25.395 18536-18536 example.app252 com.example.app2526 W Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed) 2025-05-27 18:30:25.395 18536-18536 example.app252 com.example.app2526 W Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed) 2025-05-27 18:30:25.643 18536-18559 HostConnection com.example.app2526 D HostConnection::get() New Host Connection established 0xd4552b50, tid 18559 2025-05-27 18:30:25.647 18536-18559 HostConnection com.example.app2526 D HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_has_shared_slots_host_memory_allocator ANDROID_EMU_vulkan_free_memory_sync ANDROID_EMU_vulkan_shader_float16_int8 ANDROID_EMU_vulkan_async_queue_submit ANDROID_EMU_sync_buffer_data ANDROID_EMU_vulkan_async_qsri ANDROID_EMU_read_color_buffer_dma GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_2 2025-05-27 18:30:25.648 18536-18559 OpenGLRenderer com.example.app2526 W Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without... 2025-05-27 18:30:25.663 18536-18559 EGL_emulation com.example.app2526 D eglCreateContext: 0xd455b6e0: maj 2 min 0 rcv 2 2025-05-27 18:30:25.696 18536-18559 EGL_emulation com.example.app2526 D eglMakeCurrent: 0xd455b6e0: ver 2 0 (tinfo 0xd4646730) (first time) 2025-05-27 18:30:25.738 18536-18559 Gralloc4 com.example.app2526 I mapper 4.x is not supported 2025-05-27 18:30:25.739 18536-18559 HostConnection com.example.app2526 D createUnique: call 2025-05-27 18:30:25.739 18536-18559 HostConnection com.example.app2526 D HostConnection::get() New Host Connection established 0xd455ae90, tid 18559 2025-05-27 18:30:25.794 18536-18559 HostConnection com.example.app2526 D HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_has_shared_slots_host_memory_allocator ANDROID_EMU_vulkan_free_memory_sync ANDROID_EMU_vulkan_shader_float16_int8 ANDROID_EMU_vulkan_async_queue_submit ANDROID_EMU_sync_buffer_data ANDROID_EMU_vulkan_async_qsri ANDROID_EMU_read_color_buffer_dma GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_2 2025-05-27 18:30:27.372 18536-18536 VideoPlayer com.example.app2526 E 初始化错误 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.VideoView.setMediaController(android.widget.MediaController)' on a null object reference at com.example.app2526.Fragment_3.initVideoPlayer(Fragment_3.java:125) at com.example.app2526.Fragment_3.onViewCreated(Fragment_3.java:103) at androidx.fragment.app.Fragment.performViewCreated(Fragment.java:2987) at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:546) at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:282) at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:2189) at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:2100) at androidx.fragment.app.FragmentManager.execSingleAction(FragmentManager.java:1971) at androidx.fragment.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:311) at androidx.fragment.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:274) at androidx.viewpager.widget.ViewPager.populate(ViewPager.java:1244) at androidx.viewpager.widget.ViewPager.setCurrentItemInternal(ViewPager.java:669) at androidx.viewpager.widget.ViewPager.setCurrentItemInternal(ViewPager.java:631) at androidx.viewpager.widget.ViewPager.setCurrentItem(ViewPager.java:612) at com.example.app2526.MainActivity$2.onNavigationItemSelected(MainActivity.java:87) at com.google.android.material.navigation.NavigationBarView$1.onMenuItemSelected(NavigationBarView.java:301) at androidx.appcompat.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:836) at androidx.appcompat.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:159) at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:987) at com.google.android.material.navigation.NavigationBarMenuView$1.onClick(NavigationBarMenuView.java:141) at android.view.View.performClick(View.java:7448) at android.view.View.performClickInternal(View.java:7425) at android.view.View.access$3600(View.java:810) at android.view.View$PerformClick.run(View.java:28305) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7656) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 2025-05-27 18:30:27.373 18536-18536 Compatibil...geReporter com.example.app2526 D Compat change id reported: 147798919; UID 10189; state: ENABLED 2025-05-27 18:30:30.266 18536-18536 VideoPlayer com.example.app2526 E 初始化错误 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.VideoView.setMediaController(android.widget.MediaController)' on a null object reference at com.example.app2526.Fragment_3.initVideoPlayer(Fragment_3.java:125) at com.example.app2526.Fragment_3.onViewCreated(Fragment_3.java:103) at androidx.fragment.app.Fragment.performViewCreated(Fragment.java:2987) at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:546) at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:282) at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:2189) at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:2100) at androidx.fragment.app.FragmentManager.execSingleAction(FragmentManager.java:1971) at androidx.fragment.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:311) at androidx.fragment.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:274) at androidx.viewpager.widget.ViewPager.populate(ViewPager.java:1244) at androidx.viewpager.widget.ViewPager.setCurrentItemInternal(ViewPager.java:669) at androidx.viewpager.widget.ViewPager.setCurrentItemInternal(ViewPager.java:631) at androidx.viewpager.widget.ViewPager.setCurrentItem(ViewPager.java:612) at com.example.app2526.MainActivity$2.onNavigationItemSelected(MainActivity.java:87) at com.google.android.material.navigation.NavigationBarView$1.onMenuItemSelected(NavigationBarView.java:301) at androidx.appcompat.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:836) at androidx.appcompat.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:159) at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:987) at com.google.android.material.navigation.NavigationBarMenuView$1.onClick(NavigationBarMenuView.java:141) at android.view.View.performClick(View.java:7448) at android.view.View.performClickInternal(View.java:7425) at android.view.View.access$3600(View.java:810) at android.view.View$PerformClick.run(View.java:28305) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7656) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 2025-05-27 18:30:30.678 18536-18567 ProfileInstaller com.example.app2526 D Installing profile for com.example.app2526
05-29
好的，我现在需要帮助用户解决他们Android应用中出现的多个错误，包括“Channel isunrecoverably broken”、“BufferQueue abandoned”、“PROCESSENDED”和“NullPointerException(setMediaControlleron anull ...
Android开发笔记（一百三十九）可定制可滑动的标签栏
aqi00的博客
03-28 3335
App在页面底部展现标签栏导航的效果，有多种实现方式，包括TabActivity方式、ActivityGroup方式、FragmentActivity方式等等，具体的实现方案参见之前的博文《Android开发笔记（十九）底部标签栏》。一般情况下这种底部标签栏能够满足大部分的业务需求，然而有时客户的口味比较独特，固定的几款套餐已经不能满足她的胃口了。比如客户要求做成自助餐形式，同时长条的固定餐台也要
请优化以下android代码：main.java :package com.example.myapplication.Fragment; import android.graphics.Color; import android.os.Bundle; import android.view.View; import android.widget.TextView; import androidx.appcompat.app.AppCompatActivity; import androidx.fragment.app.Fragment; import androidx.fragment.app.FragmentTransaction; import androidx.viewpager.widget.ViewPager; import com.example.myapplication.R; import com.example.myapplication.Viewpagerhd.Mypageradapter; import java.util.ArrayList; import java.util.List; public class Fragment_main extends AppCompatActivity implements View.OnClickListener { private Fragment fragment1, fragment2, fragment3; private TextView tab1, tab2, tab3; private ViewPager myViewpager; private List<Fragment> fragmentList; private Mypageradapter mypageradapter; private Fragment currentFragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_fragment1); initUI(); // initFragments(); initTab(); } private void initTab() { fragmentList = new ArrayList<Fragment>(); fragmentList.add(new Fragmenta_1()); fragmentList.add(new Fragmenta_2()); fragmentList.add(new Fragmenta_3()); // 使用修正后的适配器 mypageradapter = new Mypageradapter(getSupportFragmentManager(), fragmentList); myViewpager.setAdapter(mypageradapter); myViewpager.addOnPageChangeListener(new MyPageChangeListennr()); // 修正监听器设置 showFragment(0); } private void showFragment(int i) { myViewpager.setCurrentItem(i); if (i == 0){ tab1.setBackgroundColor(Color.RED); tab2.setBackgroundColor(Color.WHITE); tab3.setBackgroundColor(Color.WHITE); }else if (i==1){ tab2.setBackgroundColor(Color.RED); tab1.setBackgroundColor(Color.WHITE); tab3.setBackgroundColor(Color.WHITE); }else if (i==2){ tab3.setBackgroundColor(Color.RED); tab2.setBackgroundColor(Color.WHITE); tab1.setBackgroundColor(Color.WHITE); } } public class MyPageChangeListennr implements ViewPager.OnPageChangeListener { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { if (position==0){ tab1.setBackgroundColor(Color.RED); tab2.setBackgroundColor(Color.WHITE); tab3.setBackgroundColor(Color.WHITE); }else if (position==1){ tab2.setBackgroundColor(Color.RED); tab1.setBackgroundColor(Color.WHITE); tab3.setBackgroundColor(Color.WHITE); }else if (position==2){ tab3.setBackgroundColor(Color.RED); tab2.setBackgroundColor(Color.WHITE); tab1.setBackgroundColor(Color.WHITE); } } @Override public void onPageScrollStateChanged(int state) { } } private void initUI() { tab1 = findViewById(R.id.T1); tab2 = findViewById(R.id.T2); tab3 = findViewById(R.id.T3); tab1.setOnClickListener(this); tab2.setOnClickListener(this); tab3.setOnClickListener(this); myViewpager =(ViewPager) findViewById(R.id.myviewpage); // updateTabColors(R.id.T1); } // private void initFragments() { // FragmentTransaction transaction = getSupportFragmentManager().beginTransaction(); // // // 按顺序添加所有Fragment // fragment1 = new Fragmenta_1(); // fragment2 = new Fragmenta_2(); // fragment3 = new Fragmenta_3(); // // transaction.add(R.id.view_pager, fragment1, "1"); // transaction.add(R.id.view_pager, fragment2, "2"); // transaction.add(R.id.view_pager, fragment3, "3"); // // transaction.hide(fragment2); // transaction.hide(fragment3); // transaction.commitNow(); // 立即提交事务 // // currentFragment = fragment1; // } @Override public void onClick(View v) { if (v.getId()==R.id.T1) { showFragment(0); }else if (v.getId()==R.id.T2){ showFragment(1); }else if (v.getId()==R.id.T3){ showFragment(2); } } private void switchFragment(Fragment targetFragment, int tabId) { if (targetFragment == currentFragment) return; FragmentTransaction transaction = getSupportFragmentManager().beginTransaction(); transaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out); transaction.hide(currentFragment); transaction.show(targetFragment); transaction.commitNow(); // 使用立即提交 currentFragment = targetFragment; updateTabColors(tabId); } private void updateTabColors(int selectedTabId) { int defaultColor = Color.WHITE; int selectedColor = Color.RED; tab1.setBackgroundColor(selectedTabId == R.id.T1 ? selectedColor : defaultColor); tab2.setBackgroundColor(selectedTabId == R.id.T2 ? selectedColor : defaultColor); tab3.setBackgroundColor(selectedTabId == R.id.T3 ? selectedColor : defaultColor); } } 适配器：package com.example.myapplication.Fragment; import androidx.fragment.app.Fragment; import androidx.fragment.app.FragmentManager; import androidx.fragment.app.FragmentPagerAdapter; import java.util.List; public class Mypageradapter extends FragmentPagerAdapter { private List<Fragment> fragmentList; public Mypageradapter(FragmentManager fm) { super(fm); } public Mypageradapter(FragmentManager fm, List<Fragment>fragmentList) { super(fm); this.fragmentList=fragmentList; } @Override public Fragment getItem(int position) { return fragmentList.get(position); } @Override public int getCount() { return fragmentList.size(); } } 运行日志：2025-05-29 13:58:01.366 22820-22820/? E/e.myapplicatio: Unknown bits set in runtime_flags: 0x8000 2025-05-29 13:58:02.024 22820-22820/com.example.myapplication E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.myapplication, PID: 22820 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplication/com.example.myapplication.Fragment.Fragment_main}: java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference at com.example.myapplication.Viewpagerhd.Mypageradapter.getCount(Mypageradapter.java:40) at androidx.viewpager.widget.ViewPager.setAdapter(ViewPager.java:532) at com.example.myapplication.Fragment.Fragment_main.initTab(Fragment_main.java:46) at com.example.myapplication.Fragment.Fragment_main.onCreate(Fragment_main.java:35) at android.app.Activity.performCreate(Activity.java:7802) at android.app.Activity.performCreate(Activity.java:7791) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)  at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)  at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)  at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)  at android.os.Handler.dispatchMessage(Handler.java:107)  at android.os.Looper.loop(Looper.java:214)  at android.app.ActivityThread.main(ActivityThread.java:7356)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)  运行时，代码没有报错，但是应用打不开，只是闪一下就退出
最新发布
05-30
根据运行日志，错误是NullPointerException，发生在Mypageradapter的getCount方法中，提示List.size()在空对象上调用。这说明适配器的fragmentList可能未被正确初始化或者传递。首先，我需要检查适配器的构造函数。...
[android] viewpager获取当前view报空指针的解决方法
flyingfox023的专栏
03-19 994
因为需求,我需要获得viewpager当前的view 于是我采用以下写法 [java] view plaincopy View currentView = mViewPager.getChildAt(mViewPager.getCurrentItem());   然后我拿这个view去做其他的事,但是滑动超过3个view后,再拿这
findViewById中NullPointerException的错误
欢迎关注公众号：【码农突围】，公号后台回复9999，可以获取一份500页的LeetCode刷题笔记。
08-06 3135
findViewById中NullPointerException的错误
android中findViewById(R.id.XXX)提示空指针异常NullPointerException的原因
birdbeyondl的专栏
08-22 6837
注：转自  http://wangzhen19900908.iteye.com/blog/1515038 造成这种结果一般有3中情况 第一是：未加载布局文件，也就是没有设置布局之前，就findViewById(),这样肯定获取不到了 第二是：View应该是树形的组织，从当前所在的contentview中找不到，要设置contentview为包含有所要find的co
关于获得ViewPager的item的View为null问题
qq_32228265的博客
05-25 1125
在获取ViewPager的item的View时在使用这种方法时，在滑动后获取View会View为null View childAt = viewPager.getChildAt(viewPager.getCurrentItem()); 可在PagerAdapter中获得View @Override public void setPrimaryItem(ViewGroup contai
findViewById()返回null
maoqimaoqi的博客
07-06 823
今天在重写BaseAdapter的getView()方法时，下面两行代码报空指针。 TextView tv_title = (TextView) findViewById(R.id.tv_title); ImageView iv_icon = (ImageView) findViewById(R.id.iv_icon); 后来查了一下，findViewById()返回n
viewPager = findViewById(R.id.viewPager);的viewpager报错
05-29
如果你的 `findViewById(R.id.viewPager)` 报错，有可能是以下几个原因： 1. 没有在 XML 文件中定义 `ViewPager` 控件，或者 ID 名称不正确。请检查你的 XML 文件中是否有一个 `ViewPager` 控件，并且其 ID 是否为 ...
评论
添加红包

请填写红包祝福语或标题

个

红包个数最小为10个

元

红包金额最低5元

当前余额3.43元 前往充值 >
需支付：10.00元
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付元
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明：

1.余额是钱包充值的虚拟货币，按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载，可以购买VIP、付费专栏及课程。

余额充值