android - 如何从使用 Fragment 的 ViewPager2 获得用户点击?
问题描述
我期待用户点击片段内的按钮。我正在使用 ViewPager2 在不同的片段之间滑动。
在其中一个片段中,我有一个要设置 onClickListener 的按钮,但是当我尝试在 onOcreateView 上设置按钮的 onClickListener 时,出现此错误:
E/InputEventReceiver: Exception dispatching input event.
A/cifireca.words: java_vm_ext.cc:570] JNI DETECTED ERROR IN APPLICATION: JNI CallVoidMethodV called with pending exception java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
java_vm_ext.cc:570] at android.view.View cifireca.words.FragmentStock.onCreateView(android.view.LayoutInflater, android.view.ViewGroup, android.os.Bundle) (FragmentStock.java:40)
java_vm_ext.cc:570] at void androidx.fragment.app.Fragment.performCreateView(android.view.LayoutInflater, android.view.ViewGroup, android.os.Bundle) (Fragment.java:2600)
java_vm_ext.cc:570] at void androidx.fragment.app.FragmentManagerImpl.moveToState(androidx.fragment.app.Fragment, int, int, int, boolean) (FragmentManagerImpl.java:881)
java_vm_ext.cc:570] at void androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(androidx.fragment.app.Fragment) (FragmentManagerImpl.java:1238)
java_vm_ext.cc:570] at void androidx.fragment.app.BackStackRecord.executeOps() (BackStackRecord.java:434)
java_vm_ext.cc:570] at void androidx.fragment.app.FragmentManagerImpl.executeOps(java.util.ArrayList, java.util.ArrayList, int, int) (FragmentManagerImpl.java:2079)
java_vm_ext.cc:570] at void androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(java.util.ArrayList, java.util.ArrayList, int, int) (FragmentManagerImpl.java:1869)
java_vm_ext.cc:570] at void androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(java.util.ArrayList, java.util.ArrayList) (FragmentManagerImpl.java:1824)
java_vm_ext.cc:570] at void androidx.fragment.app.FragmentManagerImpl.execSingleAction(androidx.fragment.app.FragmentManagerImpl$OpGenerator, boolean) (FragmentManagerImpl.java:1696)
java_vm_ext.cc:570] at void androidx.fragment.app.BackStackRecord.commitNow() (BackStackRecord.java:293)
java_vm_ext.cc:570] at void androidx.viewpager2.adapter.FragmentStateAdapter.placeFragmentInViewHolder(androidx.viewpager2.adapter.FragmentViewHolder) (FragmentStateAdapter.java:341)
java_vm_ext.cc:570] at void androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(androidx.viewpager2.adapter.FragmentViewHolder) (FragmentStateAdapter.java:276)
java_vm_ext.cc:570] at void androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(androidx.recyclerview.widget.RecyclerView$ViewHolder) (FragmentStateAdapter.java:67)
我可以看到它确实是由 setOnClickListener 引起的,但是我不确定如何解决这个问题。
我实现 onClickListener 的方法如下:
public class FragmentStock extends Fragment {
...
private Button buttonAccept;
...
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
ViewGroup viewGroup = (ViewGroup) inflater.inflate(R.layout.fragment_stock, container, false);
...
buttonAccept = viewGroup.findViewWithTag(R.id.button_stockAccept);
buttonAccept.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
... do whatever
}
});
return viewGroup;
}
...
}
解决方案
使用findViewById
而不是findViewWithTag
我认为它应该可以解决您的问题。
buttonAccept = viewGroup.findViewById(R.id.button_stockAccept);
推荐阅读
- c# - 强制 Cortana 聆听 - 除了用鼠标点击还有其他方法吗?
- sbt - build.sbt 使用任务更改设置
- python - 在 python 中出现错误为“**系列的真值不明确”
- c# - C# 卡在 StringBuilder 循环中
- php - 在 html 中暴露 id 是否安全
- javascript - jquery show() 关闭面板后不起作用
- javascript - 如何根据点击显示和隐藏内容
- google-chrome-extension - Chrome 扩展运行时 onInstalled 与 onStartup 事件顺序
- javascript - 在 Bing for Mobile 上使用 JavaScript 打开多个选项卡
- postgresql - 如何解决 Ubuntu 18.04 上未安装 Postgresql Client 的错误