问题描述

使用shared preferences如何删除list item？

我有下面的adapter自定义类，创建了listview和items，但是我想在点击reset按钮时，从list中删除所有的items。

public class Scores extends Activity implements OnClickListener {public static final String MY_PREFS_NAME = ""PrefName"";SharedPreferences pref;static String[] tempTime = new String[10];static String[] tempScore = new String[10];private static class EfficientAdapter extends BaseAdapter {    private LayoutInflater mInflater;    public EfficientAdapter(Context context) {        mInflater = LayoutInflater.from(context);    }    public int getCount() {        return tempTime.length;    }    public Object getItem(int position) {        return position;    }    public long getItemId(int position) {        return position;    }    public View getView(int position View convertView ViewGroup parent) {        ViewHolder holder;        if (convertView == null) {            convertView = mInflater.inflate(                    R.layout.mathmatch_score_format null);            holder = new ViewHolder();            holder.text1 = (TextView) convertView                    .findViewById(R.id.time_text);            holder.text2 = (TextView) convertView                    .findViewById(R.id.score_text);            /*final ImageView deleteButton = (ImageView)                     convertView.findViewById(R.id.score_reset);            deleteButton.setOnClickListener(this);*/            convertView.setTag(holder);            //deleteButton.setTag(holder);        } else {            holder = (ViewHolder) convertView.getTag();        }        holder.text1.setText(tempTime[position]);        holder.text2.setText(tempScore[position]);        return convertView;    }    static class ViewHolder {        TextView text1;        TextView text2;    }}@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.mathmatch_score);    setUpViews();    pref = getSharedPreferences(MY_PREFS_NAME 0);    strTime = pref.getString(""high_score_times""");    intScore = pref.getString(""high_score_values""");    tempTime = strTime.split("");    tempScore = intScore.split("");    Comparator<String> comparator = new CustomArrayComparator<String String>(tempScore tempTime);    Arrays.sort(tempTime comparator);    Arrays.sort(tempScore Collections.reverseOrder());    lv.setAdapter(new EfficientAdapter(this));}private void setUpViews() {    lv = (ListView) findViewById(R.id.list);    reset = (ImageView) findViewById(R.id.score_reset);    reset.setOnClickListener(this);}   @Overrideprotected void onPause() {    super.onPause();    pref = getSharedPreferences(MY_PREFS_NAME 0);    SharedPreferences.Editor edit = pref.edit();    edit.putString(""high_score_times"" strTime);    edit.putString(""high_score_values"" intScore);    edit.commit();}@Overrideprotected void onStop() {    super.onStop();}@Overridepublic void onClick(View v) {    switch (v.getId()) {    case R.id.score_reset:        AlertDialog.Builder alertbox = new AlertDialog.Builder(this);        alertbox.setTitle(""Reset"");        alertbox.setMessage(""Are you sure all time ans score are reset?"");        alertbox.setPositiveButton(""Yes"" new DialogInterface.OnClickListener() {                     public void onClick(DialogInterface arg0 int arg1) {                         pref = getSharedPreferences(MY_PREFS_NAME 0);                        SharedPreferences.Editor edit = pref.edit();                        /*edit.remove(""high_score_times"");                        edit.remove(""high_score_values"");*/                        /*edit.remove(intScore);                        edit.remove(strTime);                        */                        //edit.clear();                        edit.remove(MY_PREFS_NAME);                        edit.commit();                             }        });                    alertbox.setNegativeButton(""No"" new DialogInterface.OnClickListener() {                     public void onClick(DialogInterface arg0 int arg1) {                Toast.makeText(getApplicationContext()'No' button clicked"" Toast.LENGTH_SHORT).show();            }        });         alertbox.show();           break;      default:        break;}}}

Reset按钮不在list中。上面的代码是点击yes按钮事件，但是没有任何更新。如何改正这个问题呢？

解决方案

EfficientAdapter adapter;//设为全局变量
当list数据改变后，需要调用adapter.notifyDataSetChanged();
这样显示才会改变.