Question

我最近开始研究Android项目，由于我对UI编程缺乏了解，当我尝试动态地向UI添加条目时，我发现自己处于修复状态。

我正在开发一个聊天应用程序，当收到新消息时，应该在底部添加。为此，我需要通知数据集已更改。当我直接调用数据集发生了变化时，我收到了一个错误。所以我在适配器上使用了本地广播接收器。

不幸的是，我不知道如何传递包含HashMap的ArrayList。我将发布适配器的代码以及我尝试通知数据已更改的位置。我希望有人可以帮助我。谢谢了很多..： - ）

代码：

    public static void recieveUpdatedMessage(String channelName, Map<String, Object> input){

//The input here contains message from our PUSH system 

  Intent intent = new Intent();
                    HashMap<String, String> insertMap = new HashMap<>();
                    insertMap.put(chatText, String.valueOf(input.get("text")));
                    insertMap.put(firstName,String.valueOf("firstname"));
                    insertMap.put(groupChannel, "/service/chat" + String.valueOf(groupAccountId));

                    ArrayList<HashMap<String, String>> chatMessagesHashMapList = new ArrayList<HashMap<String, String>>();
                    chatMessagesHashMapList.add(insertMap);

// Below is where I am trying to send data.
                 //  intent.putExtra(chatMessagesHashMapList);//send any data to your adapter
                    intent.setAction("myaction");
                    LocalBroadcastManager.getInstance(context).sendBroadcast(intent);

适配器代码，它位于同一个java文件中：

public class ChatMessagesAdapter extends BaseAdapter {


private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent)
    {

        if(intent.getAction().equals("MYREFRESH"))
        {
            notifyDataSetChanged();
        }
    }
};

    private Activity activity = null;
    private ArrayList<HashMap<String, String>> data;
    private LayoutInflater inflater = null;


    public ChatMessagesAdapter(Activity a, ArrayList<HashMap<String, String>> d) {

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("MYREFRESH");
        LocalBroadcastManager.getInstance(context).registerReceiver(broadcastReceiver, intentFilter);

        activity = a;
        data = d;
        inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {


        View vi = convertView;
        if (convertView == null)
            vi = inflater.inflate(R.layout.chat_messages_row, parent, false);

        TextView chatText = (TextView) vi.findViewById(R.id.chatText);
        ImageView userImage = (ImageView) vi.findViewById(R.id.chatImage);
        TextView firstName = (TextView) vi.findViewById(R.id.personName);

        HashMap<String, String> chatList = new HashMap<>();
        chatList = data.get(position);

        chatText.setText(chatList.get(ChatMessagesActivity.chatText));
        userImage.setImageBitmap(convertByteArrayToBitmap(chatList.get(ChatMessagesActivity.chatImage)));
        firstName.setText(chatList.get(ChatMessagesActivity.firstName));
        return vi;
    }

}

我希望我很清楚。如果有任何遗漏，请告诉我。如何告诉活动有新消息并将其放在底部。

Answer 1

您可以使用bundle将您使用HashMap创建数据的最新数据直接传递给intent。＆安培;从BroadCastReceiver的onReceive方法中检索它

如何传递数据检查下面的更新方法recieveUpdatedMessage 的 recieveUpdatedMessage

public static void recieveUpdatedMessage(String channelName, Map<String, Object> input) { //The input here contains message from our PUSH system Intent intent = new Intent(); HashMap<String, String> insertMap = new HashMap<>(); insertMap.put(chatText, String.valueOf(input.get("text"))); insertMap.put(firstName, String.valueOf("firstname")); insertMap.put(groupChannel, "/service/chat" + String.valueOf(groupAccountId)); ArrayList<HashMap<String, String>> chatMessagesHashMapList = new ArrayList<HashMap<String, String>>(); // Added your map into Bundler as a Serializable Bundle bundle = new Bundle(); bundle.putSerializable("chatMapKey", insertMap); // after adding map into bundle . bundle is added into Intent intent.putExtras(bundle); // Below is where I am trying to send data. // intent.putExtra(chatMessagesHashMapList);//send any data to your adapter intent.setAction("MYREFRESH"); LocalBroadcastManager.getInstance(context).sendBroadcast(intent); }

如何从捆绑包中检索数据在列表视图中更新它，请检查您的ChatMessagesAdapter更新代码。

<强> ChatMessagesAdapter

public class ChatMessagesAdapter extends BaseAdapter { private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { if (intent.getAction().equals("MYREFRESH")) { Bundle bundle = intent.getExtras(); // Get the bundle from intent if (bundle!=null && bundle.containsKey("chatMapKey")) { // get the Serializable object which is pass as a broadcast from the Bundle refreshChat((HashMap<String, String>) bundle.getSerializable("chatMapKey")); } } } }; private Activity activity = null; private ArrayList<HashMap<String, String>> data; private LayoutInflater inflater = null; private int size = 0; public ChatMessagesAdapter(Activity a, ArrayList<HashMap<String, String>> d) { IntentFilter intentFilter = new IntentFilter(); intentFilter.addAction("MYREFRESH"); LocalBroadcastManager.getInstance(context).registerReceiver(broadcastReceiver, intentFilter); activity = a; data = d; if (data != null) size = data.size(); inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); } public void refreshChat(HashMap<String, String> newChatMap) { if (data == null) {// Added Condition for safe side you can remove it data = new ArrayList<HashMap<String, String>>(); } data.add(newChatMap); size = data.size(); notifyDataSetChanged(); } @Override public int getCount() { return size; } @Override public Object getItem(int position) { return position; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { View vi = convertView; if (convertView == null) vi = inflater.inflate(R.layout.chat_messages_row, parent, false); TextView chatText = (TextView) vi.findViewById(R.id.chatText); ImageView userImage = (ImageView) vi.findViewById(R.id.chatImage); TextView firstName = (TextView) vi.findViewById(R.id.personName); HashMap<String, String> chatList = new HashMap<>(); chatList = data.get(position); chatText.setText(chatList.get(ChatMessagesActivity.chatText)); userImage.setImageBitmap(convertByteArrayToBitmap(chatList.get(ChatMessagesActivity.chatImage))); firstName.setText(chatList.get(ChatMessagesActivity.firstName)); return vi; } }

<强> 建议

避免像使用过的那样使用广播接收器。注册活动onReusme / onStart＆amp;在onPause / onStop中取消注册方法check this The visible lifetime

尝试使用数据库维护数据，就像在消息时一样接收将其插入数据库＆amp;在刷新数据时获取来自数据库的数据

Answer 2

你真的不应该那样使用BroadcastReceiver。尝试向add添加Adapter方法，以便更轻松地添加项目并自动通知更改。

public void add(HashMap<String, String> item) {
    data.add(item);
    notifyDataSetChanged();
}

然后在recieveUpdatedMessage方法中，您可以执行与以下内容类似的操作。

public void recieveUpdatedMessage(String channelName, Map<String, Object> input) {
    HashMap<String, String> insertMap = new HashMap<>();
    insertMap.put(chatText, input.get("text").toString());
    insertMap.put(firstName, input.get("firstname").toString());
    insertMap.put(groupChannel, "/service/chat" + input.get("groupaccountid").toString());

    myAdapter.add(insertMap);
}

一些需要改进的注意事项

最好不要使用HashMap，而是创建一个类来为您保存数据。

由于您的BaseAdapter已使用List，因此您可以扩展ArrayAdapter，因为它已经有一个add方法，默认情况下也会调用notifyDataSetChanged()

Android：更新数据集，其中数据集是HashMaps

2 个答案: