Question

我正在制作一个Android聊天应用程序。我有一个recyclerview显示消息。我对邮件有两种不同的布局，一种用于发送，一种用于接收。我的recyclerview不会引发任何错误，但是在屏幕上没有显示任何内容。

这是我的适配器类：

public class ChatAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<Chat> items;

private final int USER = 1, CONTACT = 2;

// Provide a suitable constructor (depends on the kind of dataset)
public ChatAdapter(List<Chat> items) {
    this.items = items;
}

// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
    return this.items.size();
}

@Override
public int getItemViewType(int position) {
    if(items.get(position).getType()==1)
        return USER;
    else
        return CONTACT;
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
    RecyclerView.ViewHolder viewHolder;
    LayoutInflater inflater = LayoutInflater.from(viewGroup.getContext());
    switch (viewType){
        case USER:
            View v1 = inflater.inflate(R.layout.chat_item_user, viewGroup, false);
            viewHolder = new ViewHolder1(v1);
            break;
        default:
            View v2 = inflater.inflate(R.layout.chat_item_contact, viewGroup, false);
            viewHolder = new ViewHolder1(v2);

    }
    return viewHolder;
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
    switch (viewHolder.getItemViewType()) {
        case USER:
            ViewHolder1 vh1 = (ViewHolder1) viewHolder;
            configureViewHolder1(vh1, position);
            break;
        default:
            ViewHolder2 vh2 = (ViewHolder2) viewHolder;
            configureViewHolder2(vh2, position);
            break;
    }
}
public void configureViewHolder1(ViewHolder1 viewHolder, int position){
    Chat chat = items.get(position);
    viewHolder.getTv().setText(chat.getMsg());
}
public void configureViewHolder2(ViewHolder2 viewHolder, int position){
    Chat chat = items.get(position);
    viewHolder.getTv().setText(chat.getMsg());
}

}

这是我的聊天课：

public class Chat {
private int type;
private String msg;
private long time;
public Chat(int type,long time,String msg){this.type = type; this.msg = msg; this.time = time;}
public int getType(){return type;}
public void setType(int type){this.type = type;}
public String getMsg(){return msg;}
public void setMsg(String msg){this.msg = msg;}
public long getTime(){return time;}
public void setTime(long time){this.time = time;}
}

这是我的包含recylcerview的布局：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ChatActivity">

<TextView
    android:id="@+id/textView3"
    android:layout_width="368dp"
    android:layout_height="59dp"
    android:layout_marginEnd="9dp"
    android:layout_marginStart="7dp"
    android:layout_marginTop="16dp"
    android:background="@android:color/holo_green_light"
    android:text="TextView"
    android:textSize="30sp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />


<android.support.v7.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="368dp"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    android:layout_height="394dp"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView3" />

<EditText
    android:id="@+id/editText8"
    android:layout_width="325dp"
    android:layout_height="wrap_content"
    android:layout_marginBottom="5dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="1dp"
    android:ems="10"
    android:inputType="textMultiLine"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toStartOf="@+id/imageButton"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/recyclerView" />

<ImageButton
    android:id="@+id/imageButton"
    android:layout_width="53dp"
    android:layout_height="54dp"
    android:scaleType="fitCenter"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/recyclerView"
    app:srcCompat="@drawable/logo_arrow" />

这是我的两种布局：

a。 chat_item_contact

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content">

<TextView
    android:id="@+id/textView5"
    android:layout_width="323dp"
    android:layout_height="wrap_content"
    android:layout_marginBottom="10dp"
    android:layout_marginEnd="16dp"
    android:layout_marginStart="45dp"
    android:layout_marginTop="16dp"
    android:background="@android:color/holo_green_light"
    android:paddingLeft="10dp"
    android:text="TextView"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

b。 chat_item_user

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content">

<TextView
    android:id="@+id/textView4"
    android:layout_width="329dp"
    android:layout_height="wrap_content"
    android:layout_marginBottom="10dp"
    android:layout_marginEnd="48dp"
    android:layout_marginStart="7dp"
    android:layout_marginTop="7dp"
    android:background="@android:color/holo_green_light"
    android:paddingLeft="10dp"
    android:text="TextView"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

Answer 1

我做过类似的事情，您应该主要关注getItemViewType 这是我的做法（我也建议您使用RecyclerView代替ListView）

@Override
public int getItemViewType(int position){
    if (/*your condition based on message received or sent*/) {
        return VIEW_MESSAGE_RECEIVED;
    }
    else {
        return VIEW_MESSAGE_SENT;
    }
}

之后，您只需检查getItemViewType返回了什么

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    if (viewType == VIEW_MESSAGE_RECEIVED) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.chat_message_item_received, parent, false);

        return new ChatAdapter.MyViewHolder(view);
    }else {
        View eventDataView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.chat_message_item_sent, parent, false);

        return new ChatAdapter.MyViewHolder(view);
    }
}

Answer 2

尝试此代码。删除listitem空检查，因为一旦赋值，它就不会为空。

如果在显示一种布局时显示的布局比在另一种布局中显示的布局消失的情况下，添加的内容还要多。

            if (currentChat.getType() == 1) {
            listItem1 = LayoutInflater.from(context).inflate(R.layout.chat_item_user, parent, false);
            listItem1.setVisibility(View.VISIBLE);
            listItem2.setVisibility(View.GONE);
        } else {
            listItem2 = LayoutInflater.from(context).inflate(R.layout.chat_item_contact, parent, false);
            listItem2.setVisibility(View.VISIBLE);
            listItem1.setVisibility(View.GONE);
        }

为recyclerview中的每个视图添加不同的布局

2 个答案: