如何从 ArrayAdapter <POJO>动态设置微调器的值

Question

所以我花了将近3个小时来寻找如何使用pojo的阵列adapter将价值设置为旋转器的答案。

这是我的pojo：

public class ArchiveIssueModel implements Serializable {
private String Issues;
private String id;
private String Picture;
public ArchiveIssueModel(String issues, String id, String picture) {
    Issues = issues;
    this.id = id;
    Picture = picture;
}

public ArchiveIssueModel() {
}
public ArchiveIssueModel(String issue) {
    this.Issues = issue;
}
public String getIssues() {
    return Issues;
}
public void setIssues(String issues) {
    Issues = issues;
}
public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public String getPicture() {
    return Picture;
}
public void setPicture(String picture) {
    Picture = picture;
}
//to display object as a string in spinner
@Override
public String toString() {
    return Issues;
}
@Override
public boolean equals(Object obj) {
    if(obj instanceof ArchiveIssueModel){
        ArchiveIssueModel c = (ArchiveIssueModel )obj;
        if(c.getIssues().equals(Issues) && c.getId()== id ) return true;
    }
    return false;
}

我知道如何使用字符串的和阵列设置值。我这样做了，这很容易理解。

ArrayAdapter<String> spinnerArrayAdapter =
            new ArrayAdapter<>(this,
                    android.R.layout.simple_spinner_item, yearList);
    spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    sp_year.setAdapter(spinnerArrayAdapter);
    sp_year.setSelection(spinnerArrayAdapter.getPosition(year));

但是，如果ArrayAdapter O ArchiveIssueModel(即我的POJO(，我无法弄清楚如何为旋转器设置值。任何帮助，将不胜感激。ty：(

Answer 1

它与您写的相同，但仅提供适配器的POJO类列表。

ArrayList<ArchiveIssueModel> list = new ArrayList<>();
ArrayAdapter<ArchiveIssueModel> spinnerArrayAdapter =
        new ArrayAdapter<ArchiveIssueModel>(getActivity(),
                android.R.layout.simple_spinner_item, list);
spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
sp_year.setAdapter(spinnerArrayAdapter);
// What it means?
sp_year.setSelection(spinnerArrayAdapter.getPosition(year));

Answer 2

我们需要定义适配器，以描述将Java对象转换为视图的过程(在GetView方法中(。对此的天真方法(没有任何视图缓存(看起来如下：

    public class UsersAdapter extends ArrayAdapter<User> {
    // View lookup cache
    private static class ViewHolder {
        TextView name;
        TextView home;
    }

    public UsersAdapter(Context context, ArrayList<User> users) {
       super(context, R.layout.item_user, users);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
       // Get the data item for this position
       User user = getItem(position);    
       // Check if an existing view is being reused, otherwise inflate the view
       ViewHolder viewHolder; // view lookup cache stored in tag
       if (convertView == null) {
          // If there's no view to re-use, inflate a brand new view for row
          viewHolder = new ViewHolder();
          LayoutInflater inflater = LayoutInflater.from(getContext());
          convertView = inflater.inflate(R.layout.item_user, parent, false);
          viewHolder.name = (TextView) convertView.findViewById(R.id.tvName);
          viewHolder.home = (TextView) convertView.findViewById(R.id.tvHome);
          // Cache the viewHolder object inside the fresh view
          convertView.setTag(viewHolder);
       } else {
           // View is being recycled, retrieve the viewHolder object from tag
           viewHolder = (ViewHolder) convertView.getTag();
       }
       // Populate the data from the data object via the viewHolder object 
       // into the template view.
       viewHolder.name.setText(user.name);
       viewHolder.home.setText(user.hometown);
       // Return the completed view to render on screen
       return convertView;
   }
}

注意：将用户POJO更改为您的POJO类。