我在build.gradle中使用以下依赖项:
compile 'com.google.firebase:firebase-database:11.4.2'
compile 'com.firebaseui:firebase-ui-database:3.1.0'
compile 'com.firebaseui:firebase-ui-auth:3.1.0'
我的目标是使用Firebase数据库中的数据填充Listview
。
我按照Github Firebase上的指南进行操作
以下方法应将数据绑定到listview:
private void showMessages() {
Query query = FirebaseDatabase.getInstance()
.getReference("notfication/unread/" + userMailAddress.replace(".", ","))
.orderByKey();
FirebaseListOptions<Message> options = new FirebaseListOptions.Builder<Message>()
.setLayout(R.layout.fbmessage_listitem)//Note: The guide doesn't mention this method, without it an exception is thrown that the layout has to be set.
.setQuery(query, Message.class)
.build();
FirebaseListAdapter<Message> adapter = new FirebaseListAdapter<Message>(options) {
@Override
protected void populateView(View v, Message model, int position) {
TextView tvMessage = v.findViewById(R.id.tv_message);
tvMessage.setText(model.getDateTimeCreated());
}
};
ListView readMessageList = findViewById(R.id.lvReadMessageList);
readMessageList.setAdapter(adapter);
}
这是包含TextViews的布局。
<LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="0.6" android:orientation="vertical"> <TextView android:id="@+id/tv_created_on" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="start" android:gravity="start" android:paddingStart="5dp" android:paddingEnd="0dp" android:textColor="@android:color/black" /> <TextView android:id="@+id/tv_message" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="start" android:gravity="start" android:paddingStart="5dp" android:paddingEnd="0dp" android:textColor="@android:color/black" /> </LinearLayout> <ImageView android:id="@+id/iv_message_read" android:layout_width="200dp" android:layout_height="30dp" android:layout_weight="0.2" android:contentDescription="@string/message_read" android:elevation="2dp" app:srcCompat="@drawable/android_ok_sign" /> <ImageView android:id="@+id/iv_delete" android:layout_width="200dp" android:layout_height="30dp" android:layout_weight="0.2" android:contentDescription="@string/abc_delete" android:elevation="2dp" android:src="@drawable/ic_delete_red_48dp" />
模特:
public class Message {
private String message;
private String sender;
private String receiver;
private long timestamp;
private boolean isRead;
private String userMailAddress;
public Message() {
}
public Message(String message, String sender, String receiver, long timestamp, boolean isRead) {
this.message = message;
this.sender = sender;
this.receiver = receiver;
this.timestamp = timestamp;
this.isRead = isRead;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public String getSender() {
return sender;
}
public void setSender(String sender) {
this.sender = sender;
}
public String getReceiver() {
return receiver;
}
public void setReceiver(String receiver) {
this.receiver = receiver;
}
public long getTimestamp() {
return timestamp;
}
public void setTimestamp(long timestamp) {
this.timestamp = timestamp;
}
public boolean isRead() {
return isRead;
}
public void setRead(boolean read) {
isRead = read;
}
public String getUserMailAddress() {
return userMailAddress;
}
public void setUserMailAddress(String userMailAddress) {
this.userMailAddress = userMailAddress;
}
public String getDateTimeCreated() {
Calendar calendar = Calendar.getInstance(Locale.getDefault());
calendar.setTimeInMillis(timestamp);
String date = DateFormat.format("dd-MM-yyyy", calendar).toString();
String time = DateFormat.format("HH:mm", calendar).toString();
return date + "\r\n" + time;
}
}
无论我尝试什么,设置断点或记录TAG,方法populateView将模型中的数据绑定到文本域都不被调用。 我在之前的FirebaseUI中使用相同的布局(仍然在我的生产应用程序中),一切都在那里正常工作。
有谁知道为什么覆盖方法populateView没有被调用?
答案 0 :(得分:8)
我遇到了同样的问题,修复了:
@Override
protected void onStart() {
super.onStart();
mAdapter.startListening();
}
然后
@Override
protected void onStop() {
super.onStop();
mAdapter.stopListening();
}
像更新前一样工作: - )
答案 1 :(得分:4)
我遇到了同样的问题。我尝试了接受的答案,但代码在startListening
语句中失败并且空指针异常(适配器为空!)。
经过大量研究后,我在示例代码中添加了.setLifecycleOwner(this)
(例如,参见下面的代码)。它就像一个魅力!
FirebaseListOptions<Message> options = new FirebaseListOptions.Builder<Message>()
.setLayout(R.layout.fbmessage_listitem)//Note: The guide doesn't mention this method, without it an exception is thrown that the layout has to be set.
.setQuery(query, Message.class)
.setLifecycleOwner(this) //Added this
.build();
答案 2 :(得分:3)
这可能是查询中的拼写错误吗? notifications
代替notification
?尝试在FirebaseListAdapter#onChildChanged()
中放置一个断点,看看是否有任何事件进入。
最有可能的原因是你没有打电话给FirebaseListAdapter#startListening()
。除非您使用FirebaseListOptions#setLifecycleOwner(...)
的Android架构组件,否则必须手动manage your adapter's lifecycle。这意味着调用startListening()
中的onStart()
和stopListening()
中的onStop()
。
PS:我建议您查看性能优于ListView的RecyclerView。