我正在开发一个聊天应用程序，我对使用ListViews和ArrayAdapter以及自定义适配器非常陌生。我遇到的问题导致我的列表中的所有项目都是一个布局，即使它们应该根据布尔值进行更改（真正的是一个外向聊天泡泡，而false将是一个传入的聊天泡泡）。
这是我的聊天记录的代码（它不是整个文件，只是一个片段）：
变量声明：
final ArrayList<chatBubble> objects = new ArrayList<>();
final CustomAdapter customAdapter = new CustomAdapter(this, objects);
listView.setAdapter(customAdapter);
获取邮件并添加到列表的代码：
mDatabase.child("chat").child("publicDump").child("dumpedMessages").child("message" + i).addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
final String message = dataSnapshot.getValue(String.class);
if (message != null) {
final String extract = message.substring(message.lastIndexOf("<") + 1, message.indexOf(">"));
mDatabase.child("users").child("c").child("emailToUsername").child(mAuth.getCurrentUser().getEmail().replace(".", ",")).child("username").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String username = dataSnapshot.getValue(String.class);
if (username != null) {
if (username.equals(extract)) {
Log.i("Extract", extract);
int semicnt = 0;
int num = 0;
//Log.i("Loop", "Yes");
for (int i = 0; i < message.length(); i++) {
//Log.i("Loop", "y");
if (String.valueOf(message.charAt(i)).equals(":")) {
semicnt++;
//Log.i("cnt", String.valueOf(semicnt));
if (semicnt == 3) {
num = i;
i = message.length() - 1;
String time = message.substring(0, (Math.min(message.length(), num)));
String finalM = message.replace(time + ": ", "").replace("<" + extract + "> ", "");
chatBubble chat = new chatBubble(finalM, "From: " + extract + " At: " + time, true);
objects.add(chat);
}
}
}
} else {
int semicnt = 0;
int num = 0;
// Log.i("Loop", "Yes");
for (int i = 0; i < message.length(); i++) {
//Log.i("Loop", "y");
if (String.valueOf(message.charAt(i)).equals(":")) {
semicnt++;
//Log.i("cnt", String.valueOf(semicnt));
if (semicnt == 3) {
num = i;
i = message.length() - 1;
String time = message.substring(0, (Math.min(message.length(), num)));
String finalM = message.replace(time + ": ", "").replace("<" + extract + "> ", "");
chatBubble chat = new chatBubble(finalM, "From: " + extract + " At: " + time, false);
objects.add(chat);
}
}
}
}
customAdapter.notifyDataSetChanged();
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
以下是我的chatBubble的代码：
package com.tejasmehta.codeychat;
public class chatBubble {
private String msg;
private String date;
private boolean myMessage;
public chatBubble(String msg, String date, boolean myMessage) {
this.msg = msg;
this.date = date;
this.myMessage = myMessage;
}
public String Msg() {
return msg;
}
public String Date() {
return date;
}
public boolean myMessage() {
return myMessage;
}
}
这是我的customAdapter的代码（显示如果boolean，myMessage为true，它将加载不同的布局，而另一个布局为false）：
public class CustomAdapter extends BaseAdapter {
private LayoutInflater inflater;
private ArrayList<chatBubble> objects;
private class ViewHolder {
TextView msg;
TextView date;
}
public CustomAdapter(Context context, ArrayList<chatBubble> objects) {
inflater = LayoutInflater.from(context);
this.objects = objects;
}
public int getCount() {
return objects.size();
}
public chatBubble getItem(int position) {
return objects.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
int layoutResource; // determined by view type
chatBubble ChatBubble = getItem(position);
if (ChatBubble.myMessage()) {
layoutResource = R.layout.right_bubble;
} else {
layoutResource = R.layout.left_bubble;
}
if(convertView == null) {
holder = new ViewHolder();
convertView = inflater.inflate(layoutResource, null);
holder.msg = convertView.findViewById(R.id.txt_msg);
holder.date = convertView.findViewById(R.id.date);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.msg.setText(objects.get(position).Msg());
holder.date.setText(objects.get(position).Date());
return convertView;
}
}
感谢您的帮助！
答案 0 :(得分：0)
问题是你的getview 该视图正在被回收，因此convertview已经有了一个布局。所以它没有被重新定义为正确的布局。
你需要使用getViewType（）和getViewTypeCount（）来告诉列表视图你想要使用不同的布局 http://android.amberfog.com/?p=296
@Override
public int getViewTypeCount() {
return 2;
}
@Override
public int getItemViewType(int position) {
return getItem(position).myMessage()?0:1;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
int layoutResource; // determined by view type
chatBubble ChatBubble = getItem(position);
if (ChatBubble.myMessage()) {
layoutResource = R.layout.right_bubble;
} else {
layoutResource = R.layout.left_bubble;
}
if(convertView == null) {
holder = new ViewHolder();
convertView = inflater.inflate(layoutResource, null);
holder.msg = convertView.findViewById(R.id.txt_msg);
holder.date = convertView.findViewById(R.id.date);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.msg.setText(objects.get(position).Msg());
holder.date.setText(objects.get(position).Date());
return convertView;
}