java - 每次我必须改变一些东西来反映
问题描述
在我的聊天应用程序 FriendsFragment 中显示空白。如果我想反映这一点，我已经运行了该应用程序，在我的应用程序中打开“朋友”选项卡，然后在 Android Studio 中即时运行后，它就会反映。如果没有，那么我必须在我的 FriendsFragment 中的任何位置添加 Log 语句，并使用完全打开的 friendsfragmet 选项卡运行 Instant run。
为什么我告诉你添加 Log 语句是必要的，因为我发现了这个错误，每当我在我的 Friends Fragment 上更改某些内容然后运行 Instant run 时，它只会显示 Fragment 部分。而且我每次都必须这样做，否则它不会显示。添加 Log 语句并第二次删除，或更改标签或更改消息，做一些更改，并且必须运行即时运行（那个黄色符号，如助推器）。
注意：我还在做这个事情，我自己观察到这个问题，我也不知道为什么我每次都要改变一些东西来显示这个片段？我也在同一个应用程序中构建了类似的片段，但是没有问题！
朋友片段
package com.jimmytrivedi.lapitchat;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.support.v7.app.AlertDialog;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
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;
import com.squareup.picasso.Picasso;
import de.hdodenhof.circleimageview.CircleImageView;
public class FriendsFragment extends Fragment {
private RecyclerView FriendRecyclerView;
private DatabaseReference databaseReference, UsersDatabaseReference;
private FirebaseAuth mAuth;
private String currentUID;
private View MainView;
public FriendsFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
MainView = inflater.inflate(R.layout.fragment_friend, container, false);
FriendRecyclerView = MainView.findViewById(R.id.FriendRecyclerView);
mAuth = FirebaseAuth.getInstance();
if (mAuth.getCurrentUser() != null) {
currentUID = mAuth.getCurrentUser().getUid();
databaseReference = FirebaseDatabase.getInstance().getReference().child("Friends").child(currentUID);
databaseReference.keepSynced(true);
UsersDatabaseReference = FirebaseDatabase.getInstance().getReference().child("Users");
UsersDatabaseReference.keepSynced(true);
}
FriendRecyclerView.setHasFixedSize(true);
FriendRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
Log.d("wihddiewd", "Is it going?");
return MainView;
}
@Override
public void onStart() {
super.onStart();
Query query = FirebaseDatabase. getInstance()
.getReference()
.child("Friends")
.limitToLast(50);
FirebaseRecyclerOptions<Friends> options = new FirebaseRecyclerOptions.Builder<Friends>()
.setQuery(query, Friends.class)
.build();
final FirebaseRecyclerAdapter<Friends, FriendsViewHolder> FriendsRecyclerViewAdapter = new
FirebaseRecyclerAdapter<Friends, FriendsViewHolder>(options) {
@Override
protected void onBindViewHolder(@NonNull final FriendsViewHolder holder, int position, @NonNull Friends model) {
holder.setDate(model.getDate());
final String listUID = getRef(position).getKey();
UsersDatabaseReference.child(listUID).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
final String userName = dataSnapshot.child("Name").getValue().toString();
String thumbImage = dataSnapshot.child("thumbImage").getValue().toString();
String userOnline = dataSnapshot.child("Online").getValue().toString();
holder.setName(userName);
holder.setThumbImage(thumbImage, getContext());
holder.setUserOnline(userOnline);
holder.mView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
CharSequence options[] = new CharSequence[]{"Open profile", "Send message"};
AlertDialog.Builder builder = new AlertDialog.Builder(getContext());
builder.setTitle("Select Options");
builder.setItems(options, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (which == 0) {
Intent intent = new Intent(getContext(), ProfileActivity.class);
intent.putExtra("userID", listUID);
startActivity(intent);
}
if (which == 1) {
Intent intent = new Intent(getContext(), ChatActivity.class);
intent.putExtra("userID", listUID);
intent.putExtra("userName", userName);
startActivity(intent);
}
}
});
builder.show();
}
});
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
@NonNull
@Override
public FriendsViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.users_single_layout, parent, false);
return new FriendsViewHolder(view);
}
};
FriendRecyclerView.setAdapter(FriendsRecyclerViewAdapter);
FriendsRecyclerViewAdapter.startListening();
}
public static class FriendsViewHolder extends RecyclerView.ViewHolder {
View mView;
public FriendsViewHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void setDate(String date) {
TextView userStatusView = mView.findViewById(R.id.userStatus);
userStatusView.setText(date);
}
public void setName(String name) {
TextView userNameView = mView.findViewById(R.id.userName);
userNameView.setText(name);
}
public void setThumbImage(String thumbImage, Context context) {
CircleImageView circleImageView = mView.findViewById(R.id.userImage);
Picasso.get().load(thumbImage).placeholder(R.drawable.defaultimage)
.into(circleImageView);
}
public void setUserOnline(String online) {
ImageView userOnline = mView.findViewById(R.id.online);
if (online.equals("true")) {
userOnline.setVisibility(View.VISIBLE);
} else {
userOnline.setVisibility(View.INVISIBLE);
}
}
}
}
更新
我知道这是一个奇怪的错误。但基本上，当我打开我的应用程序并在应用程序朋友选项卡（即 FriendsFragment.java）中，它显示为空白。所以我尝试调试我的代码是否有任何错误？但我没有找到。但是在调试时，当我转到移动应用程序中的朋友选项卡并将任何日志语句放入 Android Studio 时（因为当我添加/删除某些内容时，Android Studio 会理解发生了一些更改，然后我运行 Instant run （不是正常运行）然后 FriendFragment 将反映并显示用户列表。
而且我每次都必须这样做，（意味着我必须添加/删除一些东西，考虑对 Android Studio 的更改）然后只有 FriendsFragment 会显示用户列表。即使我没有打开我的朋友选项卡，而是在应用程序中打开其他东西而不是运行（即时运行），这也是行不通的！只有当我只是去朋友选项卡（那个时候它显示为空白，但没关系）并运行即时运行时，它才会反映。
片段朋友.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".FriendsFragment">
<android.support.v7.widget.RecyclerView
android:id="@+id/FriendRecyclerView"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</android.support.v7.widget.RecyclerView>
</RelativeLayout>
users_single_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<de.hdodenhof.circleimageview.CircleImageView
android:id="@+id/userImage"
android:layout_width="64dp"
android:layout_height="64dp"
android:layout_marginBottom="15dp"
android:layout_marginLeft="15dp"
android:layout_marginTop="15dp"
android:src="@drawable/defaultimage" />
<TextView
android:id="@+id/userName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignTop="@+id/userImage"
android:layout_marginStart="99dp"
android:text="Display Name"
android:textColor="#000000"
android:textSize="18dp" />
<TextView
android:id="@+id/userStatus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignStart="@+id/userName"
android:layout_below="@+id/userName"
android:text="User default Status"
android:textSize="15dp" />
<ImageView
android:id="@+id/online"
android:layout_width="8dp"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/userName"
android:layout_marginLeft="10dp"
android:layout_toEndOf="@+id/userName"
android:visibility="invisible"
android:src="@drawable/online" />
</RelativeLayout>
另一个片段 ChatFragment，与此类似并且工作得很好）。
聊天片段.java
package com.jimmytrivedi.lapitchat;
import android.content.Context;
import android.content.Intent;
import android.graphics.Typeface;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
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;
import com.squareup.picasso.Picasso;
import de.hdodenhof.circleimageview.CircleImageView;
public class ChatFragment extends Fragment {
private RecyclerView ConversationList;
private DatabaseReference ConversationRef, MessageRef, UserRef;
private FirebaseAuth mAuth;
private String currentUID;
private View MainView;
public ChatFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
MainView = inflater.inflate(R.layout.fragment_chat, container, false);
ConversationList = MainView.findViewById(R.id.ConversationList);
mAuth = FirebaseAuth.getInstance();
currentUID = mAuth.getCurrentUser().getUid();
ConversationRef = FirebaseDatabase.getInstance().getReference().child("Chat").child(currentUID);
ConversationRef.keepSynced(true);
UserRef = FirebaseDatabase.getInstance().getReference().child("Users");
UserRef.keepSynced(true);
MessageRef = FirebaseDatabase.getInstance().getReference().child("Messages").child(currentUID);
LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
layoutManager.setReverseLayout(true);
layoutManager.setStackFromEnd(true);
ConversationList.setHasFixedSize(true);
ConversationList.setLayoutManager(layoutManager);
return MainView;
}
@Override
public void onStart() {
super.onStart();
Query conversationQuery = ConversationRef.orderByChild("timestamp");
Query query = FirebaseDatabase.getInstance()
.getReference()
.child("Chat")
.limitToLast(50);
FirebaseRecyclerOptions<Conversation> options = new FirebaseRecyclerOptions.Builder<Conversation>()
.setQuery(query, Conversation.class)
.build();
FirebaseRecyclerAdapter<Conversation, ConversationViewHolder> ConversationRecyclerViewAdapter = new
FirebaseRecyclerAdapter<Conversation, ConversationViewHolder>(options) {
@Override
protected void onBindViewHolder(@NonNull final ConversationViewHolder holder, int position, @NonNull final Conversation model) {
final String listUID = getRef(position).getKey();
Query lastMessageQuery = MessageRef.child(listUID).limitToLast(1);
lastMessageQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
String data = dataSnapshot.child("message").getValue().toString();
holder.setMassage(data, model.isSeen());
}
@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
UserRef.child(listUID).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
final String userName = dataSnapshot.child("Name").getValue().toString();
String userThumb = dataSnapshot.child("thumbImage").getValue().toString();
if (dataSnapshot.hasChild("Online")) {
String userOnline = dataSnapshot.child("Online").getValue().toString();
holder.setUserOnline(userOnline);
}
holder.setName(userName);
holder.setUserImage(userThumb, getContext());
holder.mView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getContext(), ChatActivity.class);
intent.putExtra("userID", listUID);
intent.putExtra("userName", userName);
startActivity(intent);
}
});
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
@NonNull
@Override
public ConversationViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.users_single_layout, parent, false);
return new ConversationViewHolder(view);
}
};
ConversationList.setAdapter(ConversationRecyclerViewAdapter);
ConversationRecyclerViewAdapter.startListening();
}
public static class ConversationViewHolder extends RecyclerView.ViewHolder {
View mView;
public ConversationViewHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void setMassage(String message, boolean isSeen) {
TextView userStatusView = mView.findViewById(R.id.userStatus);
userStatusView.setText(message);
if (!isSeen) {
userStatusView.setTypeface(userStatusView.getTypeface(), Typeface.BOLD);
} else {
userStatusView.setTypeface(userStatusView.getTypeface(), Typeface.NORMAL);
}
}
public void setUserOnline(String online) {
ImageView userOnlineView = mView.findViewById(R.id.online);
if (online.equals("true")) {
userOnlineView.setVisibility(View.VISIBLE);
} else {
userOnlineView.setVisibility(View.INVISIBLE);
}
}
public void setName(String userName) {
TextView userNameView = mView.findViewById(R.id.userName);
userNameView.setText(userName);
}
public void setUserImage(String userThumb, Context context) {
CircleImageView userImageView = mView.findViewById(R.id.userImage);
Picasso.get().load(userThumb).placeholder(R.drawable.defaultimage).into(userImageView);
}
}
}
朋友.java
package com.jimmytrivedi.lapitchat;
public class Friends {
public String date;
public Friends() {
}
public Friends(String date) {
this.date = date;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
}
SectionPagerAdapter.java
package com.jimmytrivedi.lapitchat;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
RequestFragment requestFragment = new RequestFragment();
return requestFragment;
case 1:
ChatFragment chatFragment = new ChatFragment();
return chatFragment;
case 2:
FriendsFragment friendFragment = new FriendsFragment();
return friendFragment;
default:
return null;
}
}
@Override
public int getCount() {
return 3;
}
@Nullable
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Requests";
case 1:
return "Chats";
case 2:
return "Friends";
default:
return null;
}
}
}
MainActivity.java
package com.jimmytrivedi.lapitchat;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import com.facebook.login.LoginManager;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ServerValue;
public class MainActivity extends AppCompatActivity {
private FirebaseAuth mAuth;
private FirebaseUser currentUser;
private Toolbar toolbar;
private ViewPager viewPager;
private SectionsPagerAdapter sectionsPagerAdapter;
private TabLayout tabLayout;
private DatabaseReference UserDatabaseReference;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
currentUser = mAuth.getCurrentUser();
if (currentUser == null) {
sendTostart();
} else {
UserDatabaseReference = FirebaseDatabase.getInstance().getReference().child("Users").child(mAuth.getCurrentUser().getUid());
UserDatabaseReference.child("Online").setValue("true");
}
viewPager = findViewById(R.id.viewPager);
sectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(sectionsPagerAdapter);
toolbar = findViewById(R.id.mainToolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setTitle("Home");
tabLayout = findViewById(R.id.tabLayout);
tabLayout.setupWithViewPager(viewPager);
}
@Override
protected void onPause() {
super.onPause();
if (currentUser != null) {
UserDatabaseReference.child("Online").setValue(ServerValue.TIMESTAMP);
}
}
private void sendTostart() {
startActivity(new Intent(MainActivity.this, StartActivity.class));
finish();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
getMenuInflater().inflate(R.menu.main_menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
super.onOptionsItemSelected(item);
if (item.getItemId() == R.id.logout) {
FirebaseAuth.getInstance().signOut();
LoginManager.getInstance().logOut();
sendTostart();
}
if (item.getItemId() == R.id.settings) {
startActivity(new Intent(MainActivity.this, SettingsActivity.class));
}
if (item.getItemId() == R.id.allUsers) {
startActivity(new Intent(MainActivity.this, UsersActivity.class));
}
return true;
}
}
解决方案
利用
`viewPager.setOffscreenPageLimit(3);`
后
viewPager.setAdapter(sectionsPagerAdapter);
在 MainActivity 中。
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