Question

我从数据库中获取第一个数据，listview将显示数据。目前，当多次调用列表时，数据将附加到列表的末尾。

有没有办法清除listview，以便新数据再次位于listView的顶部

public class AndroidTestActivity extends Activity 
{
    JSONArray jArray;
    String result = null;
    InputStream is = null;
    StringBuilder sb=null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button b1 = (Button) findViewById(R.id.button1);
        b1.setOnClickListener(new Button.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                EditText tv = (EditText) findViewById(R.id.editView);
                ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();

                //http get
                try{
                    HttpClient httpclient = new DefaultHttpClient();
                    HttpGet httpget = new HttpGet("http://192.168.1.132/test.php");
                    HttpResponse response = httpclient.execute(httpget);
                    HttpEntity entity = response.getEntity();
                    is = entity.getContent();
                }catch(Exception e){
                    Log.e("log_tag", "Error in http connection"+e.toString());
                }

                //convert response to string
                try{
                    BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
                    sb = new StringBuilder();
                    sb.append(reader.readLine() + "\n");

                    String line="0";
                    while ((line = reader.readLine()) != null) {
                        sb.append(line + "\n");
                    }

                    is.close();
                    result=sb.toString();
                }catch(Exception e){
                    Log.e("log_tag", "Error converting result "+e.toString());
                }

                //paring data
                int ct_id;
                String ct_name;        

                try{
                    jArray = new JSONArray(result);
                    JSONObject json_data=null;  

                    for(int i=0;i<jArray.length();i++){
                        json_data = jArray.getJSONObject(i);
                        ct_id=json_data.getInt("id");
                        ct_name=json_data.getString("name");
                        tv.append(ct_name);
                    }
                }catch(JSONException e1){
                //   Toast.makeText(getBaseContext(), "No City Found" ,Toast.LENGTH_LONG).show();
                } catch (ParseException e1) {
                    e1.printStackTrace();
                }
            }
        });
    }
}

Answer 1

清除ArryList中使用的任何对象的数组或ListView Adapter。然后再次将新数据加载到Array/ArrayList并调用adapter.notifyDataSetChanged()方法。

Answer 2

从您想要清除的代码中调用这两种方法这里的适配器是您在列表中添加它的ArrayAdapter的一个实例。

adapter.clear()
adapter.notifyDataSetChanged()

Answer 3

每次创建一个新列表并从中获取数据，并仅在此列表中添加旧数据。

Answer 4

只需写下listView.setAdapter(null)你要清除listview的地方..这对我有用..

清除Android中的ListView？

4 个答案: