Question

我想从prepopulate sqlite数据库的两个字段中检索数据。这些字段是组织名称（org_name）和联系号码（contact_no）。之后，我需要将org_name数据分配给一个大文本字段，并将contact_no分配给我的自定义列表视图中的小文本字段。

我只用一个字段试过这个。它工作正常。但是，当我试图检索两个字段时，它无法正常工作。这是我试过的。请帮我解决这个问题。

ContactView类

public class ContactView extends Activity {
private ListView listView;
private ListView listView1;
List<Organization> rowItems;
@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_view);



    DBAccess databaseAccess = DBAccess.getInstance(this);
    databaseAccess.open();
    List<String> quotes = databaseAccess.getQuotes(getIntent().getStringExtra("ID_EXTRA"));
    databaseAccess.close();


    List<Organization> rowItem=new ArrayList<Organization>();
    for(String quote:quotes){
        Organization temp=new Organization(quote);
        rowItem.add(temp);
    }
    listView = (ListView)findViewById(R.id.listView);
    CustomListViewAdapter adapter = new CustomListViewAdapter(this,
            R.layout.single_row_item, rowItem);
    listView.setAdapter(adapter);



}

数据库访问类

public class DBAccess {
private SQLiteOpenHelper openHelper;
private SQLiteDatabase database;
private static DBAccess instance;
String passedVar = null;
private ListView listView;

public DBAccess(Context context) {

    this.openHelper = new HelloDatabase(context);
}

public static DBAccess getInstance(Context context) {
    if (instance == null) {
        instance = new DBAccess(context);
    }
    return instance;
}

public void open() {
    this.database = openHelper.getWritableDatabase();
}

public void close() {
    if (database != null) {
        this.database.close();
    }
}

public List<String> getQuotes(String id) {
    List<String> list = new ArrayList<>();
    Integer value;


    if (id != null) {
        Cursor cursor = database.rawQuery("SELECT org_name,contact_no FROM org_name WHERE category_id = \"" + id + "\"", null);


        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            list.add(cursor.getString(0));
            list.add(cursor.getString(cursor.getColumnIndex("contact_no")));
            cursor.moveToNext();

        }

        cursor.close();


    }


    return list;
}}

Bean类

public class Organization {

    public String title;
    public String telenum;

    public Organization(String title,String telenum) {

        this.title = title;
        this.telenum=telenum;

    }

    public String getTitle() {

        return title;
    }
    public void setTitle(String title) {

        this.title = title;
    }

    public String getTelenum(){
        return telenum;
    }

    public void setTelenum(String telenum){
        this.telenum=telenum;
    }

}

CustomListViewAdapter类

public class CustomListViewAdapter extends ArrayAdapter<Organization> {

Context context;

public CustomListViewAdapter(Context context, int layout,
                             List<Organization> items) {
    super(context, layout, items);
    this.context = context;
}

/*private view holder class*/
private class ViewHolder {

    TextView txtTitle;
    TextView txtTele;
}

public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder = null;
    Organization rowItem = getItem(position);

    LayoutInflater mInflater = (LayoutInflater) context
            .getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.single_row_item, null);
        holder = new ViewHolder();

        holder.txtTitle = (TextView) convertView.findViewById(R.id.org_name);
        holder.txtTele = (TextView) convertView.findViewById(R.id.tele_num);

        convertView.setTag(holder);


    } else
        holder = (ViewHolder) convertView.getTag();


    holder.txtTitle.setText(rowItem.getTitle());
    holder.txtTele.setText(rowItem.getTelenum());

    return convertView;
}}

Answer 1

注意：如果任何人面临同样的问题，请使用SimpleCursorAdapter。它简单，易用，高效。找一个简单的示例here或在此帖子https://stackoverflow.com/a/37560755/5460053

上查看我的答案

由于DBAccess类的getQuotes（）方法中的以下行，它不适用于两个字段：

    cursor.moveToFirst();
    while (!cursor.isAfterLast()) {
        list.add(cursor.getString(0));//Adding org_name first. org_name is added at indexes : 0,2,4,...
        list.add(cursor.getString(cursor.getColumnIndex("contact_no")));//Then adding contact_no. contact_no is added at indexes : 1,3,5,...
        cursor.moveToNext();

    }

然后在为适配器创建数据源时，在备用索引处添加org_name和contact_no

    List<Organization> rowItem=new ArrayList<Organization>();
    for(String quote:quotes){
        Organization temp=new Organization(quote);//I wonder how this worked as there is only one contructor for Organization which is expecting 2 parameters
        rowItem.add(temp);
    }

将您的DBAccess类getQuotes（）更改为：

public List<Organization> getQuotes(String id) {
    List<Organization> list = new ArrayList<>();

    if (id != null) {
        Cursor cursor = database.rawQuery("SELECT org_name,contact_no FROM org_name WHERE category_id = \"" + id + "\"", null);

        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            Organization org = new Organization(cursor.getString(0),
                cursor.getString(cursor.getColumnIndex("contact_no")));
                list.add(org);
            cursor.moveToNext();
        }

        cursor.close();
    }
    return list;
}

将您的ContactView活动的onCreate（）更改为：

public class ContactView extends Activity {
private ListView listView;
private ListView listView1;
List<Organization> rowItems;
@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_view);

    DBAccess databaseAccess = DBAccess.getInstance(this);
    databaseAccess.open();
    List<Organization> rowItem = databaseAccess.getQuotes(getIntent().getStringExtra("ID_EXTRA"));
    databaseAccess.close();

    listView = (ListView)findViewById(R.id.listView);
    CustomListViewAdapter adapter = new CustomListViewAdapter(this,
            R.layout.single_row_item, rowItem);
    listView.setAdapter(adapter);



}

如何从预填充sqlite数据库中检索两个字段并将其分配给自定义列表视图？

1 个答案: