java - Android - Firebase - 无法将 java.util.HashMap 类型的值转换为字符串

Question

瞄准

在群聊节点内保存数据

当前数据库树

在群聊节点中，用户的消息将被发送并存储在用户选择的群聊中。

如数据库树所示，用户发送了一条消息“Hello”，他的姓名从用户节点中检索

所需的数据库树

---消息ID---是自动生成的

---用户 ID--- 从用户节点中检索

问题

允许用户发送消息Only Worked Once 的功能，这是第一次 时间。以下几次部署应用程序时，它在用户登录时崩溃。

错误 - Logcat

com.google.firebase.database.DatabaseException: Failed to convert value of type java.util.HashMap to String

ChatActivity 类 - 发送聊天消息功能

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chat);

        jGroupChatName = getIntent().getExtras().get("groupChatName").toString();
        jUserName = getIntent().getExtras().get("groupUserName").toString();
        jUserNeighbourhood = getIntent().getExtras().get("groupUserHome").toString();

        jChatToolbar = (Toolbar) findViewById(R.id.allUSersToolBar);

        jFirebaseCurrentUser = FirebaseAuth.getInstance().getCurrentUser();

        /*UserID Start - I was trying to retrieve the current user ID and add it to the Group Chat node, 
          under the selected Group Chat */
        assert jFirebaseCurrentUser != null;
        final String currentUserID = jFirebaseCurrentUser.getUid();
        jChatRoot = FirebaseDatabase.getInstance().getReference().child("Group Chats").child(jGroupChatName).child(currentUserID);
        /*UserID End*/

        jChatMessageText = (EditText) findViewById(R.id.chatMessageText);
        jChatSendTextBtn = (ImageButton) findViewById(R.id.chatSendTextBtn);

        jChatSendTextBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                Map<String, Object> groupMap = new HashMap<String, Object>();
                jGroupKey = jChatRoot.push().getKey();
                jChatRoot.updateChildren(groupMap);

                // Based on the UserID code at the top, the "currentUserID" is added as shown below
                // My intentions are to have the UserID saved under the name of the Group Chat
                // jGroupKey = (Name of selected Group Chat)

                DatabaseReference groupMessageRoot = jChatRoot.child(jGroupKey).child(currentUserID);
                Map<String, Object> groupMap2 = new HashMap<String, Object>();
                groupMap2.put("name", jUserName);
                groupMap2.put("msg", jChatMessageText.getText().toString());

                groupMessageRoot.updateChildren(groupMap2);
            }
        });
    }

相关问题

Android - Firebase - Send Users to Chat Room

future 的实现

在未来，我打算通过编写代码允许用户发送图片和视频记录，允许用户访问他们的手机相机或画廊，并将图片和视频数据发送到群聊节点，在选定的团队名字。我也想在发送后检索数据，但是当然，如​​果我无法解决它们，我会把这些留在以后的问题中。

Answer 1

不需要对所需数据库进行分支。您正在使用用户的 UID 创建不必要的级别。相反，将这一层向下合并，即合并 uid、消息和名称。然后您可以使用 someRef.orderByKey("uid").equalTo("<user_uid>")如果您需要该路径中特定用户的记录，例如聊天消息。

因此，创建一个名为 ChatMessage 的类:

public class ChatMessage {

    private String uid;
    private String name;
    private String message;
    private Long creationTime;

    public ChatMessage() {
        // Default constructor required for calls to DataSnapshot.getValue(ChatMessage.class)
    }

    public ChatMessage(String uid, String name, String message) {
        this.uid = uid;
        this.name = name;
        this.message = message;
    }

    public String getUid() {
        return uid;
    }

    public void setUid(String uid) {
        this.uid = uid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public java.util.Map<String, String> getCreationTime() {
        return ServerValue.TIMESTAMP;
    }

    @Exclude
    public Long getCreationTimeLong() {
        return creationTime;
    }

    public void setCreationTime(Long creationTime) {
        this.creationTime = creationTime;
    }
}

然后按如下方式更新您的代码:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_chat);

    chatGroupName = getIntent().getStringExtra(CHAT_GROUP_NAME);
    userKey = getIntent().getStringExtra(USER_KEY);
    user = getIntent().getParcelableExtra(USER);

    jChatToolbar = (Toolbar) findViewById(R.id.allUSersToolBar);
    jChatMessageText = (EditText) findViewById(R.id.chatMessageText);
    jChatSendTextBtn = (ImageButton) findViewById(R.id.chatSendTextBtn);

    jChatSendTextBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            sendMessage();
        }
    });
}

private void sendMessage() {
    String userMessage = jChatMessageText.getText().toString();
    chatGroupRef = FirebaseDatabase.getInstance().getReference().child("Group Chats").child(chatGroupName);

    if (!TextUtils.isEmpty(userMessage)) {
        String newChatMessageKey = chatGroupRef.push().getKey();
        ChatMessage newChatMessage = new ChatMessage(userKey, user.getName(), userMessage);
        chatGroupRef.child(newChatMessageKey).setValue(newChatMessage);
    }
}