我正在使用教程开发聊天应用程序。我已经连接了fire-base并且有ID.I安装了apk并且我正确登录。在文本框中写入文本后，单击“发送”按钮（在代码中由“fab”定义）。点击之后，上面没有显示任何内容。但它将消息存储在数据库中。我把它放在主要活动java代码中。问题是什么？
import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.text.format.DateFormat;
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.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;
public class MainActivity extends AppCompatActivity {
private static int SIGN_IN_REQUEST_CODE = 1;
private FirebaseListAdapter<ChatMessage> adapter;
RelativeLayout activity_main;
FloatingActionButton fab;
@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) {
Snackbar.make(activity_main, "You have been signed out.", Snackbar.LENGTH_SHORT).show();
finish();
}
});
}
return true;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu, menu);
return true;
}
@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) {
Snackbar.make(activity_main, "Successfully signed in.Welcome!", Snackbar.LENGTH_SHORT).show();
displayChatMessage();
} else {
Snackbar.make(activity_main, "We couldn't sign you in.Please try again later", Snackbar.LENGTH_SHORT).show();
finish();
}
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
activity_main = (RelativeLayout) findViewById(R.id.activity_main);
fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
EditText input = (EditText)findViewById(R.id.input);
FirebaseDatabase.getInstance().getReference().push().setValue(new ChatMessage(input.getText().toString(),
FirebaseAuth.getInstance().getCurrentUser().getEmail()));
input.setText("");
}
});
//check if not sign-in then navigate signin page
if (FirebaseAuth.getInstance().getCurrentUser() == null) {
startActivityForResult(AuthUI.getInstance().createSignInIntentBuilder().build(), SIGN_IN_REQUEST_CODE);
} else {
Snackbar.make(activity_main, "Welcome" + FirebaseAuth.getInstance().getCurrentUser().getEmail(), Snackbar.LENGTH_SHORT).show();
//Load content
displayChatMessage();
}
}
private void displayChatMessage() {
ListView listOfMessage = (ListView) findViewById(R.id.list_of_message);
Query query = FirebaseDatabase.getInstance().getReference().child("chats");
FirebaseListOptions<ChatMessage> options =
new FirebaseListOptions.Builder<ChatMessage>()
.setQuery(query, ChatMessage.class)
.setLayout(R.layout.list_item)
.build();
adapter = new FirebaseListAdapter<ChatMessage>(options){
@Override
protected void populateView(View v, ChatMessage model, int position) {
//get reference to the views of simple_list_item_1st_item_1.xml
TextView messageText, messageUser, messageTime;
messageText = (TextView) v.findViewById(R.id.message_text);
messageUser = (TextView) v.findViewById(R.id.message_user);
messageTime = (TextView) v.findViewById(R.id.message_time);
messageText.setText(model.getMessageText());
messageUser.setText(model.getMessageUser());
messageTime.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss))", model.getMessageTime()));
}
};
listOfMessage.setAdapter(adapter);
}
}