Android recyclerView 项目布局参数不工作

Question

我正在写一个简单的聊天记录UI。我正在使用一个九补丁文件来完成这项工作。

当我第一次用一些模拟数据初始化我的适配器时，它工作正常，但如果我在运行时添加一些东西，recyclerView 内的布局就会中断。

它不会抛出任何错误，尽管我用来设置对齐方式的布局参数似乎不起作用。实际上，对齐有效，但它的大小变为 match_parent 而不是 wrap_content。

这是我的适配器代码。

public class Adapter_Chat extends RecyclerView.Adapter<Adapter_Chat.Adapter_Chat_ViewHolder> {

private List<ChatMessageModel> data = Collections.EMPTY_LIST;

public Adapter_Chat(List<ChatMessageModel> data) {
    this.data = data;
}

@Override
public Adapter_Chat_ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    return new Adapter_Chat_ViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_rv_chat_message, parent, false));
}


public void addNewMessage(ChatMessageModel model) {
    data.add(model);
    notifyDataSetChanged();
}

@Override
public void onBindViewHolder(Adapter_Chat_ViewHolder holder, int position) {
    ChatMessageModel item = data.get(position);

    switch (item.getType()) {
        case mine: {
            holder.iv_chat_profileImage.setVisibility(View.INVISIBLE);
            holder.tv_item_chat_message_nameText.setVisibility(View.INVISIBLE);
            holder.tv_item_chat_message_contentText.setBackgroundResource(R.drawable.in_message_bg);
            RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) holder.tv_item_chat_message_contentText.getLayoutParams();
            params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
            params.height = RelativeLayout.LayoutParams.WRAP_CONTENT;
            params.width = RelativeLayout.LayoutParams.WRAP_CONTENT;
            holder.tv_item_chat_message_contentText.setLayoutParams(params);

        }
        break;

        case others: {
            holder.iv_chat_profileImage.setVisibility(View.VISIBLE);
            holder.tv_item_chat_message_nameText.setVisibility(View.VISIBLE);
            holder.tv_item_chat_message_contentText.setBackgroundResource(R.drawable.out_message_bg);
            RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) holder.tv_item_chat_message_contentText.getLayoutParams();
            params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
            params.height = RelativeLayout.LayoutParams.WRAP_CONTENT;
            params.width = RelativeLayout.LayoutParams.WRAP_CONTENT;
            holder.tv_item_chat_message_contentText.setLayoutParams(params);

        }
        break;
    }


    holder.tv_item_chat_message_contentText.setText(item.getMessage().trim());
    holder.tv_item_chat_message_nameText.setText(item.getSender().trim());
}

@Override
public int getItemCount() {
    return data.size();
}

public class Adapter_Chat_ViewHolder extends RecyclerView.ViewHolder {

    public TextView tv_item_chat_message_nameText, tv_item_chat_message_contentText;
    public ImageView iv_chat_profileImage;

    public Adapter_Chat_ViewHolder(View itemView) {
        super(itemView);
        tv_item_chat_message_contentText = (TextView) itemView.findViewById(R.id.tv_item_chat_message_contentText);
        tv_item_chat_message_nameText = (TextView) itemView.findViewById(R.id.tv_item_chat_message_nameText);
        iv_chat_profileImage = (ImageView) itemView.findViewById(R.id.iv_chat_profileImage);
    }
}
}

布局是，

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="wrap_content">

<ImageView
    android:src="@drawable/bg"
    android:scaleType="fitXY"
    android:layout_margin="16dp"
    android:layout_width="48dp"
    android:layout_height="48dp"
    android:id="@+id/iv_chat_profileImage" />

<TextView
    android:id="@+id/tv_item_chat_message_nameText"
    android:text="name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="64dp"
    android:layout_marginTop="16dp" />

<TextView
    android:layout_marginTop="32dp"
    android:layout_marginLeft="64dp"
    android:layout_marginRight="16dp"
    android:gravity="right"
    android:background="@drawable/out_message_bg"
    android:id="@+id/tv_item_chat_message_contentText"
    android:text="content"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

我的onBindViewHolder方法有问题吗？改变项目的对齐方式不应该是这样的吗？

Answer 1

addRule() 方法将保留添加到视图的现有规则。因此动态添加规则而不删除现有规则不会产生预期的效果。

像下面这样更新 switch case。

switch (item.getType()) {
    case mine: {
        ---------- exisiting code ----------
        RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) holder.tv_item_chat_message_contentText.getLayoutParams();
        params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
        params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, 0);
        params.height = RelativeLayout.LayoutParams.WRAP_CONTENT;
        params.width = RelativeLayout.LayoutParams.WRAP_CONTENT;
        holder.tv_item_chat_message_contentText.setLayoutParams(params);

    }
    break;

    case others: {
        ---------- exisiting code ----------          
        RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) holder.tv_item_chat_message_contentText.getLayoutParams();
        params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
        params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, 0);
        params.height = RelativeLayout.LayoutParams.WRAP_CONTENT;
        params.width = RelativeLayout.LayoutParams.WRAP_CONTENT;
        holder.tv_item_chat_message_contentText.setLayoutParams(params);

    }
    break;
}

对于API Level >= 17，可以使用一种新方法来删除任何现有规则，而不是将它们的值设置为0。我们可以使用

 params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, 0);

变成

 params.removeRule(RelativeLayout.ALIGN_PARENT_RIGHT);

Answer 2

Android ListView、Recycler View 或 gridView 等布局 Android 重用 UI 个对象。

在使用这种布局时，应始终记住处理 if else 条件，也就是说，如果您使用视图在一种条件下可见，则应提供其他视图以使该视图不可见，因此当listview 或 recylerview 重用视图，它将始终根据条件显示正确的视图。

在这个问题中，您还添加了规则，让我的项目在 ALIGNT_PARENT_RIGHT 上，其他项目在 ALIGN_PARENT_LEFT 上，但是您忘记添加规则，不在我的左侧和右侧显示它其他.

所以你可以使用 addRule(ALIGN_PARENT_LEFT,0) 或 removeRule(ALIGN_PARENT_LEFT) (API >= JELLY_BEAN_MR1,i.e17) addRule(ALIGN_PARENT_RIGHT,0) 或 removeRule(ALIGN_PARENT_RIGHT) (API >= JELLY_BEAN_MR1,i.e17) 我的。

Android recyclerView 项目布局参数不工作

Android recyclerView item layout params not working

android

android-relativelayout

android-recyclerview