我有一个我想做的特性，所以我可以很容易地计算和检索该类的所有实例。 我知道我需要把它推到一个阵列，但我不知道我应该如何＆＃34;存储＆＃34;数组。我使用公共，私人，静态等吗？
trait Countable
{
public $all = array();
public function addToObjects()
{
//do stuff
$this->all[] = $this->somekindofproperty;
}
}
我希望能够得到以下内容。
$c = new MyClass;
$objects = $c->all();
每个具有此特征的班级都应该拥有它自己的阵列。
答案 0 :(得分：1)
在这里，我定义了一个名为public class ChatRoomActivity extends AppCompatActivity {
private static final String TAG = "ChatRoomActivity";
static final int RC_PHOTO_PICKER = 1;
private Button sendBtn;
private EditText messageTxt;
private RecyclerView messagesList;
private ChatMessageAdapter adapter;
private ImageButton imageBtn;
private TextView usernameTxt;
private View loginBtn;
private View logoutBtn;
private FirebaseApp app;
private FirebaseDatabase database;
private FirebaseAuth auth;
private FirebaseStorage storage;
private DatabaseReference databaseRef;
private StorageReference storageRef;
private String username;
private void setUsername(String username) {
Log.d(TAG, "setUsername("+String.valueOf(username)+")");
if (username == null) {
username = "Android";
}
boolean isLoggedIn = !username.equals("Android");
this.username = username;
this.usernameTxt.setText(username);
this.logoutBtn.setVisibility(isLoggedIn ? View.VISIBLE : View.GONE);
this.loginBtn .setVisibility(isLoggedIn ? View.GONE : View.VISIBLE);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sendBtn = (Button) findViewById(R.id.sendBtn);
messageTxt = (EditText) findViewById(R.id.messageTxt);
messagesList = (RecyclerView) findViewById(R.id.messagesList);
imageBtn = (ImageButton) findViewById(R.id.imageBtn);
loginBtn = findViewById(R.id.loginBtn);
logoutBtn = findViewById(R.id.logoutBtn);
usernameTxt = (TextView) findViewById(R.id.usernameTxt);
setUsername("Android");
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
messagesList.setHasFixedSize(false);
messagesList.setLayoutManager(layoutManager);
// Show an image picker when the user wants to upload an imasge
imageBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);
}
});
// Show a popup when the user asks to sign in
loginBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
LoginDialog.showLoginPrompt(ChatRoomActivity.this, app);
}
});
// Allow the user to sign out
logoutBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
auth.signOut();
}
});
adapter = new ChatMessageAdapter(this);
messagesList.setAdapter(adapter);
adapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
public void onItemRangeInserted(int positionStart, int itemCount) {
messagesList.smoothScrollToPosition(adapter.getItemCount());
}
});
// Get the Firebase app and all primitives we'll use
app = FirebaseApp.getInstance();
database = FirebaseDatabase.getInstance(app);
auth = FirebaseAuth.getInstance(app);
storage = FirebaseStorage.getInstance(app);
// Get a reference to our chat "room" in the database
databaseRef = database.getReference("chat");
sendBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ChatMessage chat = new ChatMessage(username, messageTxt.getText().toString());
// Push the chat message to the database
databaseRef.push().setValue(chat);
messageTxt.setText("");
}
});
// Listen for when child nodes get added to the collection
databaseRef.addChildEventListener(new ChildEventListener() {
public void onChildAdded(DataSnapshot snapshot, String s) {
// Get the chat message from the snapshot and add it to the UI
ChatMessage chat = snapshot.getValue(ChatMessage.class);
adapter.addMessage(chat);
}
public void onChildChanged(DataSnapshot dataSnapshot, String s) { }
public void onChildRemoved(DataSnapshot dataSnapshot) { }
public void onChildMoved(DataSnapshot dataSnapshot, String s) { }
public void onCancelled(DatabaseError databaseError) { }
});
// When the user has entered credentials in the login dialog
LoginDialog.onCredentials(new OnSuccessListener<LoginDialog.EmailPasswordResult>() {
public void onSuccess(LoginDialog.EmailPasswordResult result) {
// Sign the user in with the email address and password they entered
auth.signInWithEmailAndPassword(result.email, result.password);
}
});
// When the user signs in or out, update the username we keep for them
auth.addAuthStateListener(new FirebaseAuth.AuthStateListener() {
public void onAuthStateChanged(FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() != null) {
// User signed in, set their email address as the user name
setUsername(firebaseAuth.getCurrentUser().getEmail());
}
else {
// User signed out, set a default username
setUsername("Android");
}
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
Uri selectedImageUri = data.getData();
// Get a reference to the location where we'll store our photos
storageRef = storage.getReference("chat_photos");
// Get a reference to store file at chat_photos/<FILENAME>
final StorageReference photoRef = storageRef.child(selectedImageUri.getLastPathSegment());
// Upload file to Firebase Storage
photoRef.putFile(selectedImageUri)
.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
// When the image has successfully uploaded, we get its download URL
Uri downloadUrl = taskSnapshot.getDownloadUrl();
// Set the download URL to the message box, so that the user can send it to the database
messageTxt.setText(downloadUrl.toString());
}
});
}
}
}
的{{1}}，并在类中用于存储对象。
trait<强>输出：
counter