我有以下代码将 SwitchCompat 与 RecyclerView 一起使用。
列出 SwitchCompat 所在的项目布局:
fragment_notification_settings_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="65dp"
android:background="@android:color/white">
<ImageView
android:id="@+id/icon"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginStart="15dp"
android:src="@drawable/settings_about"
android:scaleType="fitCenter"
android:adjustViewBounds="true"
android:layout_centerVertical="true"
android:tint="@color/Black"
tools:ignore="ContentDescription"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_toEndOf="@+id/icon"
android:layout_toStartOf="@+id/on_off_switch"
android:layout_centerVertical="true"
android:orientation="vertical">
<TextView
android:id="@+id/item_title"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:paddingStart="15dp"
android:paddingEnd="0dp"
android:text="Kaza Takibi"
android:textSize="18sp"
android:textColor="@color/Black"
tools:ignore="HardcodedText"/>
<TextView
android:id="@+id/item_description"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:paddingStart="15dp"
android:paddingEnd="0dp"
android:text="Ezan vakitlerinde namaz kılma uyarısı"
android:textSize="16sp"
android:textColor="@color/DarkGray"
tools:ignore="HardcodedText"/>
</LinearLayout>
<android.support.v7.widget.SwitchCompat
android:id="@+id/on_off_switch"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_centerVertical="true"
android:layout_alignParentEnd="true"/>
</RelativeLayout>
fragment 类:
public class NotificationSettingsFragment extends Fragment{
@Bind(R.id.close_button)
ImageView closeButtonImageView;
@Bind(R.id.recycler_view)
RecyclerView recyclerView;
private MainActivity activity;
private Context context;
private Fragment parent;
private NotificationSettingsAdapter adapter;
public NotificationSettingsFragment() {}
public void setParent(Fragment parent) {
this.parent = parent;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activity = (MainActivity)getActivity();
context = activity.getApplicationContext();
List<NotificationSettingsItem> settingsItems = new ArrayList<>();
settingsItems.add(
new NotificationSettingsItem(
"Tercihler", "",
NotificationSettingsItem.ItemType.ITEM_TYPE_SECTION_HEADER));
settingsItems.add(
new NotificationSettingsItem(
"Kaza Takibi",
"Ezan bildirimlerinde namaz kılma uyarısı",
NotificationSettingsItem.ItemType.ITEM_TYPE_APPLICATION_SETTING));
settingsItems.add(
new NotificationSettingsItem(
"Konumumu Kullan",
"Namaz vakitleri için bulunduğum konumu kullan",
NotificationSettingsItem.ItemType.ITEM_TYPE_APPLICATION_SETTING));
adapter = new NotificationSettingsAdapter(context, settingsItems);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_notification_settings, container, false);
ButterKnife.bind(this, rootView);
closeButtonImageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (parent != null) {
FragmentManager fm = activity.getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.top_container, parent);
ft.commit();
}
}
});
recyclerView.setLayoutManager(new LinearLayoutManager(context));
recyclerView.setAdapter(adapter);
return rootView;
}
private class NotificationSettingHolder extends RecyclerView.ViewHolder {
public TextView itemTitle;
public TextView itemDescription;
public SwitchCompat mSwitch;
public NotificationSettingsItem settingsItem;
public NotificationSettingHolder(View listItemRootView) {
super(listItemRootView);
mSwitch = (SwitchCompat) listItemRootView.findViewById(R.id.on_off_switch);
itemTitle = (TextView) listItemRootView.findViewById(R.id.item_title);
itemDescription = (TextView) listItemRootView.findViewById(R.id.item_description);
}
public void bindSetting(NotificationSettingsItem settingsItem){
this.settingsItem = settingsItem;
if (settingsItem.itemType == NotificationSettingsItem.ItemType.ITEM_TYPE_SECTION_HEADER) {
itemTitle.setText(settingsItem.itemTitle);
}
else if (settingsItem.itemType == NotificationSettingsItem.ItemType.ITEM_TYPE_APPLICATION_SETTING){
itemTitle.setText(settingsItem.itemTitle);
itemDescription.setText(settingsItem.itemDescription);
mSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
}
});
mSwitch.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
mSwitch.getParent().requestDisallowInterceptTouchEvent(true);
}
return false;
}
});
}
}
}
private class NotificationSettingsAdapter extends RecyclerView.Adapter<NotificationSettingHolder> {
private List<NotificationSettingsItem> settingsItems;
private LayoutInflater inflater;
public NotificationSettingsAdapter(Context context, List<NotificationSettingsItem> settingsItems) {
inflater = LayoutInflater.from(context);
this.settingsItems = settingsItems;
}
@Override
public NotificationSettingHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == NotificationSettingsItem.ItemType.ITEM_TYPE_SECTION_HEADER.ordinal()) {
return new NotificationSettingHolder(
inflater.inflate(
R.layout.fragment_settings_list_section_header,
parent,
false));
}
else if (viewType == NotificationSettingsItem.ItemType.ITEM_TYPE_APPLICATION_SETTING.ordinal()) {
return new NotificationSettingHolder(
inflater.inflate(
R.layout.fragment_notification_settings_item,
parent,
false));
}
return null;
}
@Override
public void onBindViewHolder(NotificationSettingHolder holder, int position) {
holder.bindSetting(settingsItems.get(position));
}
@Override
public int getItemCount() {
return settingsItems.size();
}
@Override
public int getItemViewType(int position) {
NotificationSettingsItem item = settingsItems.get(position);
switch (item.itemType) {
case ITEM_TYPE_APPLICATION_SETTING:
return 1;
case ITEM_TYPE_SECTION_HEADER:
return 0;
default:
return -1;
}
}
}
}
当我尝试运行它时出现此错误:
09-09 17:00:07.842 30287-30287/com.yceo.islamatlasi E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.yceo.islamatlasi, PID: 30287
java.lang.NullPointerException: Attempt to invoke interface method 'int java.lang.CharSequence.length()' on a null object reference
at android.text.StaticLayout.<init>(StaticLayout.java:49)
at android.support.v7.widget.SwitchCompat.makeLayout(SwitchCompat.java:606)
at android.support.v7.widget.SwitchCompat.onMeasure(SwitchCompat.java:526)
at android.view.View.measure(View.java:17570)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:728)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:464)
at android.view.View.measure(View.java:17570)
at android.support.v7.widget.RecyclerView$LayoutManager.measureChildWithMargins(RecyclerView.java:5446)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1328)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1265)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:522)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:1918)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:2155)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1077)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1077)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1067)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15694)
at android.view.ViewGroup.layout(ViewGroup.java:5039)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2086)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1843)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5891)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:550)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(L
我该如何处理？
提前致谢。
最佳答案
SwitchCompat 要求您指定 android:textOn 和 android:textOff
例如，你可以这样改
<android.support.v7.widget.SwitchCompat
android:id="@+id/on_off_switch"
android:textOn="On"
android:textOff="Off"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_centerVertical="true"
android:layout_alignParentEnd="true"/>
关于android - SwitchCompat 在 RecyclerView 中给出空指针异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32481856/
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