Question

数据流是正确的，我可以在日志中查看行的值，但我的视图在屏幕上不可见。有人可以查看这段代码。不确定为什么我的观点没有出现在屏幕上。

  public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        Message message = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        if (convertView == null) {
            if (message.getImagePath().isEmpty()) {
                convertView = LayoutInflater.from(getContext()).inflate(R.layout.message_text_item, parent, false);

                if (message.getSender().equalsIgnoreCase("alpha")) {
                    TextView text = (TextView) convertView.findViewById(R.id.text1);
                    text.setGravity(Gravity.LEFT);
                    text.setText(message.getText());
                } else {
                    TextView text = (TextView) convertView.findViewById(R.id.text1);
                    text.setGravity(Gravity.RIGHT);
                    text.setText(message.getText());
                }
            } else {
                convertView = LayoutInflater.from(getContext()).inflate(R.layout.message_image_item, parent, false);
                ImageView imageView = (ImageView) convertView.findViewById(R.id.imageView1);
                Picasso.with(getContext()).load(message.getImagePath()).fit().centerCrop().into(imageView);
            }
        }
        // Return the completed view to render on screen
        return convertView;
    }

message_image_item

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:srcCompat="@drawable/common_full_open_on_phone"
        android:id="@+id/imageView1" />
</LinearLayout>

message_text_item

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/linearlayout1">
    <TextView
        android:id="@+id/text1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
         />
</LinearLayout>

感谢

Answer 1

您没有重复使用虚增的视图。你应该这样做：

public View getView(int position, View convertView, ViewGroup parent) {
    // check the view creation
    if (convertView == null) {
        // inflate your view here
    } else {
        // reuse the view inflated
    }
    // set the text, image, etc.
    return convertView; // return it
}

从您的代码中，您可以选择切换到ViewType条件。这将允许您获得两个不同的布局。此外，使用ViewHolder可能会更好。这是实施：

private final static ROWTYPE_WITH_TEXT = 0;
private final static ROWTYPE_WITH_IMAGE = 1;

private class ViewHolder {
    private TextView text;
    private ImageView imageView;
}

...
@Override
public int getViewTypeCount() { return 2; }

@Override
public int getItemViewType(int position) {
    return ((Message) getItem(position)).getImagePath().isEmpty()
            ? ROWTYPE_WITH_TEXT : ROWTYPE_WITH_IMAGE;
    // if the item in the list of messages contains
    // an image path, then choose the row ROWTYPE_WITH_IMAGE
}

...
@Override
public View getView(int position, View view, ViewGroup viewGroup) {
    ViewHolder holder;
    int rowtype = getItemViewType(position); // select the rowtype

    if (view == null) {
        holder = new ViewHolder(); // init the viewholder
        LayoutInflater inflater = LayoutInflater.from(context); // init the inflater

        // select the specific layout
        if (rowtype == ROWTYPE_WITH_TEXT) {
            view = inflater.inflate(R.layout.message_text_item, null);
            holder.text = (TextView) view.findViewById(R.id.text1);

        } else {
            view = inflater.inflate(R.layout.message_image_item, null);
            holder.imageView = (ImageView) view.findViewById(R.id.imageView1);
        }

        view.setTag(holder); // keep the existing view
    } else {
        holder = (ViewHolder) view.getTag(); // reuse the view
    }

    Message message = getItem(position); // get the message

    // from the rowtype, set the elements (texts, images, etc)
    if (rowtype == ROWTYPE_WITH_TEXT)
        if (message.getSender().equalsIgnoreCase("alpha")) {
            holder.text.setGravity(Gravity.LEFT);
            holder.text.setText(message.getText());
        } else {
            holder.text.setGravity(Gravity.RIGHT);
            holder.text.setText(message.getText());
        }
    } else {
        Picasso.with(getContext())
            .load(message.getImagePath())
            .fit()
            .centerCrop()
            .into(holder.imageView);
    }

    return convertView; // return it
}

无法使用视图持有者返回listview android中不同行的不同网格布局

1 个答案: