title: Cannot resolve symbol FirebaseListAdapter
body: <p>How do I insert the FirebaseListAdapter correctly? I always get the error "Can not resolve FirebaseListAdapter". If you need something, I'll post it. The whole is supposed to spend chat messages. The error is output in line 26.</p>
  
  <p>My code:</p>
  
  <pre><code>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.google.android.gms.tasks.OnCompleteListener;
  import com.google.android.gms.tasks.Task;
  import com.google.firebase.auth.FirebaseAuth;
  import com.google.firebase.database.FirebaseDatabase;
  
  
  public class Chat extends AppCompatActivity {
      private FirebaseAuth mAuth;
      private static final int SIGN_IN_REQUEST_CODE = 123;
      private FirebaseListAdapter&lt;ChatMessage&gt; adapter; //here is the problem
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_chat);
  
  
          mAuth = FirebaseAuth.getInstance();
  
          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,
                      "Willkommen " + 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 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);
          return true;
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          if(item.getItemId() == R.id.menu_sign_out) {
              AuthUI.getInstance().signOut(this)
                      .addOnCompleteListener(new OnCompleteListener&lt;Void&gt;() {
                          @Override
                          public void onComplete(@NonNull Task&lt;Void&gt; task) {
                              Toast.makeText(Chat.this,
                                      "You have been signed out.",
                                      Toast.LENGTH_LONG)
                                      .show();
  
                              // Close activity
                              finish();
                          }
                      });
          }
          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) {
                  Toast.makeText(this,
                          "Erfolgreich eingeloggt. Willkommen!",
                          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();
              }
          }
  
      }
  
      @Override
      public void onStart() {
          super.onStart();
  
      }
  
      private void displayChatMessages() {
          ListView listOfMessages = (ListView)findViewById(R.id.list_of_messages);
  
          adapter = new FirebaseListAdapter&lt;ChatMessage&gt;(this, ChatMessage.class,
                  R.layout.message, FirebaseDatabase.getInstance().getReference()) {
              @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 messageUser = (TextView)v.findViewById(R.id.message_user);
                  TextView messageTime = (TextView)v.findViewById(R.id.message_time);
  
                  // 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()));
              }
          };
  
          listOfMessages.setAdapter(adapter);
      }
  }
  </code></pre>
  
  <p>Build Gradle</p>
  
  <pre><code>android {
      compileSdkVersion 26
      buildToolsVersion "26.0.2"
      defaultConfig {
          applicationId "de.bluestarfish.bluestarfish"
          minSdkVersion 16
          targetSdkVersion 26
          versionCode 3
          versionName "0.3.2"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation 'com.android.support.constraint:constraint-layout:1.0.2'
      compile fileTree(include: ['*.jar'], dir: 'libs')
      androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
          exclude group: 'com.android.support', module: 'support-annotations'
      })
  
  
      compile 'com.android.support:appcompat-v7:26.1.0'
      testCompile 'junit:junit:4.12'
      compile 'com.android.support:design:26.1.0'
      compile 'com.android.support:cardview-v7:26.1.0'
      compile 'com.daimajia.easing:library:2.0@aar'
      compile 'com.daimajia.androidanimations:library:2.3@aar'
      compile 'com.squareup.picasso:picasso:2.5.2'
      compile 'com.google.android.gms:play-services-ads:11.8.0'
      compile 'com.google.firebase:firebase-messaging:11.8.0'
      compile 'com.google.firebase:firebase-core:11.8.0'
      compile 'com.google.firebase:firebase-ads:11.8.0'
      compile 'com.google.firebase:firebase-auth:11.8.0'
      compile 'com.firebaseui:firebase-ui-auth:3.2.1'
      compile 'com.google.firebase:firebase-database:11.8.0'
  
  }
  
  // Add to the bottom of the file
  apply plugin: 'com.google.gms.google-services'
  </code></pre>