Question

我已经定义了我的DatabaseHelper类并且可以查询数据库。我想将数据库中的3列（名称，地点，日期）填充到ListView，其中包含3 TextViews，不知怎的，我无法将CustomAdapter设为正确。

这是错误：

CustomAdapter adapter = new CustomAdapter(this, myItems_name, myItems_venue, myItems_date);

请参阅以下完整代码：

    public class ActivityLayout extends MainActivity implements AdapterView.OnItemClickListener {

    List<String> myItems_name;
    List<String> myItems_venue;
    List<String> myItems_date;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.my_layout);


    list = (ListView) findViewById(R.id.listView);
    CustomAdapter adapter = new CustomAdapter(this, myItems_name, myItems_venue, myItems_date);
    list.setAdapter(adapter);
    list.setOnItemClickListener(this);

    }

    @Override
    public void onItemClick(AdapterView<?> adapterView, View view, int pos, long id) {
        // TODO Auto-generated method stub

        TextView tv = (TextView) findViewById(R.id.textNameSingle);
        Toast.makeText(this,tv.getText()+"", Toast.LENGTH_SHORT).show();
    }

}
////////////////////////////////////////////////////////

class CustomAdapter extends ArrayAdapter<String> {

    DatabaseHelper dbHeplper;

    private Context context;
    private List<String> myItems_name = dbHeplper.getDBData();
    private List<String> myItems_venue = dbHeplper.getDBData();
    private List<String> myItems_date = dbHeplper.getDBData();

    public CustomAdapter(Context context, int resources,  List<String> objects) {
        super(context, resources, objects);

        this.context=context;
        this.myItems_name=objects;
        this.myItems_venue=objects;
        this.myItems_date=objects;
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub

        View row=convertView;
        if(row==null)
        {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        row = inflater.inflate(R.layout.my_layout_single, parent, false);       
        }
        TextView txtArtist = (TextView) row.findViewById(R.id.textNameSingle);
        TextView txtVenue = (TextView) row.findViewById(R.id.textVenueSingle);
        TextView txtDate = (TextView) row.findViewById(R.id.textDateSingle);

        txtArtist.setText(myItems_name[position]);
        txtVenue.setText(myItems_venue[position]);
        txtDate.setText(myItems_date[position]);

        return row; 
    }   
}

更新：＃01

@ρяσѕρєяK - 我已更改我的活动和自定义适配器，如下所示:(问题仍然存在）：

活动：

    public class ActivityLayout extends MainActivity implements AdapterView.OnItemClickListener {


    List<String> myItems_name;
    List<String> myItems_venue;
    List<String> myItems_date;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.my_layout);


    list = (ListView) findViewById(R.id.listView);
    CustomAdapter adapter = new CustomAdapter(this, R.layout.my_layout, myItems_name, myItems_venue, myItems_date);
    list.setAdapter(adapter);
    list.setOnItemClickListener(this);

适配器：

    class CustomAdapter extends ArrayAdapter<String> {

    DatabaseHelper dbHeplper;

    private Context context;
    private List<String> myItems_name = dbHeplper.getDBData();
    private List<String> myItems_venue = dbHeplper.getDBData();
    private List<String> myItems_date = dbHeplper.getDBData()

    public CustomAdapter(Context context, int resources,  
            List<String> myItems_name,
        List<String> myItems_venue,
        List<String> myItems_date) {

        super(context, resources, myItems_name);

        this.context=context;
        this.myItems_name=myItems_name;
        this.myItems_venue=myItems_venue;
        this.myItems_date=myItems_date;
    }

Answer 1

您需要初始化这些值：

List<String> myItems_name;
List<String> myItems_venue;
List<String> myItems_date;

Answer 2

下面：

CustomAdapter adapter = new CustomAdapter（this，myItems_name， myItems_venue，myItems_date）;

导致问题的行，因为CustomAdapter中没有可用的构造函数，其中包含4个参数

向CustomAdapter类构造函数添加两个参数以获取myItems_name和myItems_venue：

 public CustomAdapter(Context context, int resources, 
                             List<String> myItems_name,
                             List<String> myItems_venue,
                             List<String> myItems_date) {
        super(context, resources, myItems_name);

         //.... your code here
    }

还将想要用于ListView行的布局作为第二个参数传递给CustomAdapter类构造函数：

CustomAdapter adapter = new CustomAdapter(this,R.layout.my_layout_single, 
                                myItems_name, myItems_venue, myItems_date);

Answer 3

@ρяσѕρєяK

感谢您的回答已被选中，错误现在不再存在。我补充道 dbHeplper = new DatabaseHelper（getApplicationContext（））;在onCreate下。先生，谢谢你的帮助。

@ρяσѕρєяK（见下面的更新代码）更新代码：

    public class ActivityLayout extends MainActivity implements AdapterView.OnItemClickListener {

    DatabaseHelper dbHeplper;

    ListView list;
    List<String> myItems_name;
    List<String> myItems_venue;
    List<String> myItems_date;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.my_layout);

    dbHeplper = new DatabaseHelper(getApplicationContext());

    myItems_name = dbHeplper.getDBName();
    myItems_venue = dbHeplper.getDBVenue();
    myItems_date = dbHeplper.getDBDate();

    list = (ListView) findViewById(R.id.listView);
    CustomAdapter adapter = new CustomAdapter(this, myItems_name, myItems_venue, myItems_date);
    list.setAdapter(adapter);
    list.setOnItemClickListener(this);
    }

从数据库填充ListView（带3个TextView）

3 个答案: