【发布时间】：2017-08-03 06:32:37
【问题描述】：
我有一个列表视图，我在其中加载了 json 数组数据。我有减号按钮从列表中删除行。这里的问题是我能够删除该项目，但列表视图没有得到刷新。一旦应用程序关闭或当我返回并再次导航到该活动时，列表视图就会刷新。
下面是自定义适配器类代码：
public class AddPassengerAdapater extends BaseAdapter implements ListAdapter {
private final JSONArray jsonArray;
ArrayList<String> data;
Context context;
JSONObject json_data;
LayoutInflater inflater;
public AddPassengerAdapater(Context context, JSONArray jsonArray,ArrayList<String> data) {
this.context = context;
this.jsonArray = jsonArray;
this.data = data;
String details = SessionManager.getPreferences(context,"splitfare_consumer");
data = new ArrayList<String>();
JSONArray jsonarray = null;
try {
jsonarray = new JSONArray(details);
for (int i=0; i < jsonarray.length() ; i++){
json_data = jsonarray.getJSONObject(i);
data.add(String.valueOf(json_data));
}
} catch (JSONException e) {
e.printStackTrace();
}
inflater = LayoutInflater.from(this.context);
}
@Override public int getCount() {
if(null==jsonArray)
return 0;
else
return jsonArray.length();
}
@Override public JSONObject getItem(int position) {
if(null==jsonArray) return null;
else
return jsonArray.optJSONObject(position);
}
@Override public long getItemId(int position) {
JSONObject jsonObject = getItem(position);
return jsonObject.optLong("id");
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
final MyViewHolder mViewHolder;
if (convertView == null) {
convertView = inflater.inflate(R.layout.addpassenger_row_layout, parent, false);
mViewHolder = new MyViewHolder(convertView);
convertView.setTag(mViewHolder);
}
else {
mViewHolder = (MyViewHolder) convertView.getTag();
}
json_data = getItem(position);
try {
String n = json_data.getString("name");
mViewHolder.name.setText(n);
String nu = json_data.getString("number");
mViewHolder.number.setText(nu);
} catch (JSONException e) {
e.printStackTrace();
}
mViewHolder.deletelist.setOnClickListener(new View.OnClickListener() {
JSONArray delete_jsonarray;
JSONObject jsonObject;
@Override
public void onClick(View v) {
String phonenumber = mViewHolder.number.getText().toString();
String jsonsetpreference_data = SessionManager.getPreferences(context,"splitfare_consumer");
Log.d("jsonsetpreference_data:::::::","" +jsonsetpreference_data);
try {
delete_jsonarray= new JSONArray(jsonsetpreference_data);
for (int i =0; i<= delete_jsonarray.length()-1 ; i++){
jsonObject = delete_jsonarray.getJSONObject(i);
String array_phonenumber = jsonObject.getString("number");
if (phonenumber.equals(array_phonenumber)){
delete_jsonarray.remove(i);
}
}
SessionManager.setPreferences(context,"splitfare_consumer",delete_jsonarray.toString());
} catch (JSONException e) {
e.printStackTrace();
}
}
});
return convertView;
}
private class MyViewHolder {
TextView name, number;
ImageView deletelist;
public MyViewHolder(View item) {
name = (TextView) item.findViewById(R.id.consumername);
number = (TextView) item.findViewById(R.id.consumer_number);
deletelist = (ImageView) item.findViewById(R.id.dltconsumer);
}
}
}
Listview activity code:
public class AddPassengerList extends AppCompatActivity {
@BindView(R.id.listview)
ListView listview;
@BindView(R.id.btn_addmore)
CustomFontButton btn_addmore;
@BindView(R.id.donebtn)
CustomFontButton donebtn;
public static final String TAG = "AddPassengerList";
Activity activity=this;
Context context = this;
JSONArray js;
AddPassengerAdapater adapter;
LayoutInflater inflater;
String name ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_passenger_list);
ButterKnife.bind(this);
/*Status bar color*/
Window window = activity.getWindow();
// clear FLAG_TRANSLUCENT_STATUS flag:
window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
// add FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS flag to the window
window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
// finally change the color
window.setStatusBarColor(ContextCompat.getColor(context,R.color.colorAccent));
String data = SessionManager.getPreferences(context,"splitfare_consumer");
Log.d(TAG,""+data);
ArrayList<String> details= new ArrayList<String>();
try {
js = new JSONArray(data);
} catch (JSONException e) {
e.printStackTrace();
}
adapter = new AddPassengerAdapater(context,js,details);
listview.setAdapter(adapter);
btn_addmore.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
btn_addmore.setBackgroundResource(R.drawable.addmorepassengerpressed);
break;
case MotionEvent.ACTION_UP:
btn_addmore.setBackgroundResource(R.drawable.addmorepassenger);
Intent i = new Intent(AddPassengerList.this,AddPassenger.class);
startActivity(i);
break;
}
return false;
}
});
}
}
【问题讨论】：
-
删除item后，调用notifyDataSetchanged()方法
-
我这样做了，但对我没有用
-
你的适配器类在你的活动类之外吗？
-
是的，我有单独的课程
-
现在你需要解释你的代码。您将一个 json 数组和空数据数组传递给您的构造函数，然后用它填充数据数组。然后你实际上是用 jsonArray 填充你的列表视图，而不是在任何地方使用数据数组，然后当你删除一个对象时，你正在从另一个数组 delete_array 中删除。这是如何工作的，请您解释一下这些数组是什么。