Question

我想要一个带有textview +复选框的列表视图。我能够创建列表视图。我可以捕获listview项目选择。但是，当我尝试捕获复选框选择时，取消选择我得到一个空指针异常。如何为复选框编写setOnCheckedChangeListener（）..

public class LocationActivity extends Activity{



@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    setContentView(R.layout.locationmain);

    ListView listview = (ListView) findViewById(R.id.listView1);

    String selectQuery = "SELECT  * FROM " +     DatabaseHandler.TABLE_LOCATIONLABLES;
    SQLiteDatabase db = new DatabaseHandler(this).getReadableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    final List<String> locLables = new ArrayList<String>();

    if(cursor != null){
        if (cursor.moveToFirst()) {
            do {

                locLables.add(cursor.getString(1));

            } while (cursor.moveToNext());
        }
    }

    //String[] locLables = new String[] {"Home","University","Office"};
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.locationmain_entry,R.id.textView12, locLables);

    //cb gives a null pointer exception
    CheckBox cb = (CheckBox) listview.findViewById(R.id.checkBox12);

    cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            // TODO Auto-generated method stub
            if(isChecked){
                System.out.println("selected");
            }else if(!isChecked){
                System.out.println("not selected");
            }

        }
    });     
    listview.setAdapter(adapter);


    listview.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            // TODO Auto-generated method stub
            Toast.makeText(getApplicationContext(), locLables.get(arg2), Toast.LENGTH_SHORT).show();
        }
    });
}

Answer 1

您可以维护单独的适配器类，以便轻松实现此目的....

 public class bsAdapter extends BaseAdapter
 {
   Activity cntx;
   public bsAdapter(Activity context)
   {
     // TODO Auto-generated constructor stub
     this.cntx=context;

   }

   public int getCount()
   {
     // TODO Auto-generated method stub
     return listview_arr.length;
   }

  public Object getItem(int position)
  {
     // TODO Auto-generated method stub
     return listview_arr[position];
  }

  public long getItemId(int position)
  {
     // TODO Auto-generated method stub
     return listview_array.length;
  }

  public View getView(final int position, View convertView, ViewGroup parent)
  {
     View row=null;

    LayoutInflater inflater=cntx.getLayoutInflater();
    row=inflater.inflate(R.layout.search_list_item, null);

    TextView tv=(TextView)row.findViewById(R.id.title);
    CheckBox cb=(CheckBox)row.findViewById(R.id.cb01);


    tv.setText(listview_arr[position]);

    cb.setOnClickListener(new OnClickListener(){

    public void onClick(View v) {

    if(cb.ischecked)
    {
       //ur code
    }

    else //ur code

    }
  });

  return row;
  }
 }

Answer 2

请勿使用listview.findViewById()，只需使用findViewById()，就像您在列表中所做的那样。

除非复选框是每个列表项的一部分，否则您必须访问getView()的{{1}}内的复选框。

带有textview和复选框的Listview

2 个答案: