Android Studio和Firebase - 聊天应用无法显示输入的文字

Question

我正在使用Firebase创建一个Android聊天应用...我的代码中没有任何错误，应用编译。但是，当我去测试时，输入的文字根本没有显示......

我所遵循的原始教程对于私有void displayChatMessages（）的代码略有不同，但它显示错误，因此我更改了代码。

旧代码还有其他一些代码：

ListView listOfMessages =（ListView）findViewById（R.id.list_of_messages）; listOfMessages.setAdapter（适配器）;

而且我认为我可能需要加入类似上面的东西，但我无法得到它。

任何帮助都会受到赞赏，因为我似乎无法弄明白！

package com.josephine.projectv3;

import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.firebase.ui.auth.AuthUI;
import com.firebase.ui.database.FirebaseListAdapter;
import com.firebase.ui.database.FirebaseListOptions;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;

public class Chat extends AppCompatActivity {

    private static final int SIGN_IN_REQUEST_CODE = 1;
    private FirebaseListAdapter<ChatMessage> adapter;

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


        if(FirebaseAuth.getInstance().getCurrentUser() == null) {
            // Start sign in/sign up activity
            startActivityForResult(
                    AuthUI.getInstance()
                            .createSignInIntentBuilder()
                            .build(),
                    SIGN_IN_REQUEST_CODE
            );
        } else {
            // User is already signed in. Therefore, display
            // a welcome Toast
            Toast.makeText(this,
                    "Welcome " + FirebaseAuth.getInstance()
                            .getCurrentUser()
                            .getDisplayName(),
                    Toast.LENGTH_LONG)
                    .show();

            // Load chat room contents
            displayChatMessages();
        }
        FloatingActionButton fab =
                (FloatingActionButton)findViewById(R.id.fab);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                EditText input = (EditText)findViewById(R.id.input);

                // Read the input field and push a new instance
                // of com.josephine.projectv3.ChatMessage to the Firebase database
                FirebaseDatabase.getInstance()
                        .getReference()
                        .push()
                        .setValue(new ChatMessage(input.getText().toString(),
                                FirebaseAuth.getInstance()
                                        .getCurrentUser()
                                        .getDisplayName())
                        );

                // Clear the input
                input.setText("");
            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId() == R.id.menu_sign_out) {
            AuthUI.getInstance().signOut(this)
                    .addOnCompleteListener(new OnCompleteListener<Void>() {
                        @Override
                        public void onComplete(@NonNull Task<Void> task) {
                            Toast.makeText(Chat.this,
                                    "You have been signed out.",
                                    Toast.LENGTH_LONG)
                                    .show();

                            // Close activity
                            finish();
                        }
                    });
        }
        return true;
    }
    private void displayChatMessages() {

        //Suppose you want to retrieve "chats" in your Firebase DB:
        Query query = FirebaseDatabase.getInstance().getReference().child("chats");
//The error said the constructor expected FirebaseListOptions - here you create them:
        FirebaseListOptions<ChatMessage> options = new FirebaseListOptions.Builder<ChatMessage>()
                .setQuery(query, ChatMessage.class)
                .setLayout(R.layout.message)
                .build();
        //Finally you pass them to the constructor here:

        adapter = new FirebaseListAdapter<ChatMessage>(options){
            @Override
            protected void populateView(View v, ChatMessage model, int position) {
                // Get references to the views of message.xml
                TextView messageText = (TextView)v.findViewById(R.id.message_text);
                TextView messageTime = (TextView)v.findViewById(R.id.message_time);
                TextView messageUser = (TextView)v.findViewById(R.id.message_user);

                // Set their text
                messageText.setText(model.getMessageText());
                messageUser.setText(model.getMessageUser());
                // Format the date before showing it
                messageTime.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss)", model.getMessageTime()));
            }
        };

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode,
                                    Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == SIGN_IN_REQUEST_CODE) {
            if(resultCode == RESULT_OK) {
                Toast.makeText(this,
                        "Successfully signed in. Welcome!",
                        Toast.LENGTH_LONG)
                        .show();
                displayChatMessages();
            } else {
                Toast.makeText(this,
                        "We couldn't sign you in. Please try again later.",
                        Toast.LENGTH_LONG)
                        .show();

                // Close the app
                finish();
            }
        }

    }
}

Answer 1

在发送消息后不显示消息的问题通过将单个消息的布局从相对于线性布局更改为解决

printf(const char * format, ...);