Question

这里我试图将SQLite数据库中的数据提取到自定义列表视图中，但它无法正常工作。它没有从数据库中获取数据。你可以帮助我，我的代码错了。感谢

public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.AddressBook.MESSAGE";

private ListView lv;
List<Listcollection> collectionlist;
DBHelper mydb;
Context context = this;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mydb = new DBHelper(this);

    lv = (ListView) findViewById(R.id.listView1);
    collectionlist = mydb.getList();
    lv.setAdapter(new ViewAdapter());

    // adding it to the list view.

    lv.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            // TODO Auto-generated method stub
            int id_To_Search = arg2 + 1;
            Bundle dataBundle = new Bundle();
            dataBundle.putInt("id", id_To_Search);
            Intent intent = new Intent(getApplicationContext(),
                    com.example.addressbook.Display.class);
            intent.putExtras(dataBundle);
            startActivity(intent);
        }
    });
}

public class ViewAdapter extends BaseAdapter {
    LayoutInflater mInflater;

    public ViewAdapter() {
        mInflater = LayoutInflater.from(context);
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return collectionlist.size();
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

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

        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.list_item, null);
        }

        final TextView nameText = (TextView) convertView
                .findViewById(R.id.lvname);
        nameText.setText("Name : " + collectionlist.get(position).getName());
        final TextView ageText = (TextView) convertView
                .findViewById(R.id.lvdate);
        ageText.setText("Age : " + collectionlist.get(position).getDate());

        return convertView;
    }

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.mainmenu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    super.onOptionsItemSelected(item);
    switch (item.getItemId()) {
    case R.id.item1:
        Bundle dataBundle = new Bundle();
        dataBundle.putInt("id", 0);
        Intent intent = new Intent(getApplicationContext(),
                com.example.addressbook.Display.class);
        intent.putExtras(dataBundle);
        startActivity(intent);
        return true;
    default:
        return super.onOptionsItemSelected(item);

    }

}

public boolean onKeyDown(int keycode, KeyEvent event) {
    if (keycode == KeyEvent.KEYCODE_BACK) {
        moveTaskToBack(true);
    }
    return super.onKeyDown(keycode, event);
}
}

Answer 1

试试这个

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);


lv = (ListView) findViewById(R.id.listView1);
mydb = new DBHelper(this);
lv.setAdapter(new ViewAdapter(mydb.getList()));

// adding it to the list view.

lv.setOnItemClickListener(new OnItemClickListener() {

    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
            long arg3) {
        // TODO Auto-generated method stub
        int id_To_Search = arg2 + 1;
        Bundle dataBundle = new Bundle();
        dataBundle.putInt("id", id_To_Search);
        Intent intent = new Intent(getApplicationContext(),
                com.example.addressbook.Display.class);
        intent.putExtras(dataBundle);
        startActivity(intent);
    }
});
}

public class ViewAdapter extends BaseAdapter {
LayoutInflater mInflater;
List<Listcollection> collectionlist;

public ViewAdapter(List<Listcollection> c) {
    collectionlist = c;
    mInflater = LayoutInflater.from(context);
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return collectionlist.size();
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return position;
}

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

    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.list_item, null);
    }

    final TextView nameText = (TextView) convertView
            .findViewById(R.id.lvname);
    nameText.setText("Name : " + collectionlist.get(position).getName());
    final TextView ageText = (TextView) convertView
            .findViewById(R.id.lvdate);
    ageText.setText("Age : " + collectionlist.get(position).getDate());

    return convertView;
}

}

表示同时删除全局变量集合列表

从SQLite数据库中获取数据到自定义列表视图，但它不起作用

1 个答案: