如何将数据添加到 listView 的自定义 BaseAdapter - Android [英] How to add data to custom BaseAdapter for listView - Android
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问题描述
我有一个自定义 BaseAdapter 类，可以为评论、用户名和数字创建视图.此 BaseAdapter 从 AsyncTask 接收此信息.AsyncTask 在用户到达 listView 底部时运行.问题是 BaseAdapter 不会添加新数据.当我尝试添加新数据时，它会删除列表中的当前数据，然后添加新数据.我希望它保留所有数据，并将数据添加到 listView 的底部.所有这些类都在同一个活动中.这是我当前的代码.
I have a custom BaseAdapter class that creates views for comments, usernames, and numbers. This BaseAdapter receives this information from An AsyncTask. The AsyncTask runs when the user reaches the bottom of the listView. The problem is the BaseAdapter wont add new data. When I try to add new data it deletes the current data in the list and then adds the new data. I want it to keep all the data and just add data to the bottom of the listView. All of these classes are in the same Activity. Here is my current code.
class CreateCommentLists extends BaseAdapter{
Context ctx_invitation;
String[] listComments;
String[] listNumbers;
String[] listUsernames;
public CreateCommentLists(String[] comments, String[] usernames, String[] numbers, DashboardActivity context)
{
super();
ctx_invitation = context;
listComments = comments;
listNumbers = usernames;
listUsernames = numbers;
}
@Override
public int getCount() {
if(null == listComments)
{
return 0;
}
// TODO Auto-generated method stub
return listComments.length;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return listComments[position];
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View v = null;
try
{
String inflater = Context.LAYOUT_INFLATER_SERVICE;
LayoutInflater li = (LayoutInflater)ctx_invitation.getSystemService(inflater);
v = li.inflate(R.layout.list_item, null);
TextView commentView = (TextView)v.findViewById(R.id.listComment);
TextView NumbersView = (TextView)v.findViewById(R.id.listNumber);
TextView usernamesView = (TextView)v.findViewById(R.id.listPostedBy);
Button usernameButton = (Button)v.findViewById(R.id.listUsernameButton);
Button numberButton = (Button)v.findViewById(R.id.listNumberButton);
commentView.setText(listComments[position]);
NumbersView.setText(listNumbers[position]);
usernamesView.setText(listUsernames[position]);
usernameButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(), ProfileActivity.class);
i.putExtra("usernameOfProfile",listUsernames[position]);
startActivity(i);
finish();
}
});
numberButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
Intent i = new Intent(getApplicationContext(), ProfileActivity.class);
i.putExtra("NumberProfile",listNumbers[position]);
startActivity(i);
finish();
}
});
}
catch(Exception e)
{
e.printStackTrace();
}
return v;
}
public void add(String[] comments, String[] usernames,
String[] numbers) {
listComments = comments;
listNumbers = usernames;
listUsernames = numbers;
}
public int getCount1() {
if(null == listComments)
{
return 0;
}
// TODO Auto-generated method stub
return listComments.length;
}
public Object getItem1(int position) {
// TODO Auto-generated method stub
return listComments[position];
}
public long getItemId1(int position) {
// TODO Auto-generated method stub
return 0;
}
public View getView1(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View v = null;
try
{
String inflater = Context.LAYOUT_INFLATER_SERVICE;
LayoutInflater li = (LayoutInflater)ctx_invitation.getSystemService(inflater);
v = li.inflate(R.layout.list_item, null);
TextView commentView = (TextView)v.findViewById(R.id.listComment);
TextView NumbersView = (TextView)v.findViewById(R.id.listNumber);
TextView usernamesView = (TextView)v.findViewById(R.id.listPostedBy);
Button usernameButton = (Button)v.findViewById(R.id.listUsernameButton);
Button numberButton = (Button)v.findViewById(R.id.listNumberButton);
commentView.setText(listComments[position]);
NumbersView.setText(listNumbers[position]);
usernamesView.setText(listUsernames[position]);
usernameButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(), ProfileActivity.class);
i.putExtra("usernameOfProfile",listUsernames[position]);
startActivity(i);
finish();
}
});
numberButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
Intent i = new Intent(getApplicationContext(), ProfileActivity.class);
i.putExtra("NumberProfile",listNumbers[position]);
startActivity(i);
finish();
}
});
}
catch(Exception e)
{
e.printStackTrace();
}
return v;
}
final CreateCommentLists mycmlist = new CreateCommentLists(comments, usernames, numbers, DashboardActivity.this);
lstComments = (ListView)findViewById(android.R.id.list);
lstComments.setAdapter(mycmlist);
final ProgressDialog progDailog = new ProgressDialog(DashboardActivity.this);
class loadComments extends AsyncTask<JSONObject, String, JSONObject> {
@Override
protected void onPreExecute() {
super.onPreExecute();
progDailog.setIndeterminate(false);
progDailog.setCancelable(true);
progDailog.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
progDailog.show();
progDailog.setContentView(R.layout.progress_circle);
}
@Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
}
protected JSONObject doInBackground(JSONObject... params) {
JSONObject json2 = CollectComments.collectComments(usernameforcomments, offsetNumber);
return json2;
}
@Override
protected void onPostExecute(JSONObject json2) {
try {
if (json2.getString(KEY_SUCCESS) != null) {
registerErrorMsg.setText("");
String res2 = json2.getString(KEY_SUCCESS);
if(Integer.parseInt(res2) == 1){
JSONArray commentArray = json2.getJSONArray(KEY_COMMENT);
String comments[] = new String[commentArray.length()];
for ( int i=0; i<commentArray.length(); i++ ) {
comments[i] = commentArray.getString(i);
}
JSONArray numberArray = json2.getJSONArray(KEY_NUMBER);
String numbers[] = new String[numberArray.length()];
for ( int i=0; i<numberArray.length(); i++ ) {
numbers[i] = numberArray.getString(i);
}
JSONArray usernameArray = json2.getJSONArray(KEY_USERNAME);
String usernames[] = new String[usernameArray.length()];
for ( int i=0; i<usernameArray.length(); i++ ) {
usernames[i] = usernameArray.getString(i);
}
mycmlist.add(comments,usernames,numbers);
mycmlist.notifyDataSetChanged();
}//end if key is == 1
else{
// Error in registration
registerErrorMsg.setText(json2.getString(KEY_ERROR_MSG));
}//end else
}//end if
} //end try
catch (JSONException e) {
e.printStackTrace();
}//end catch
progDailog.dismiss();
}
}
mainListView = (ListView) findViewById(android.R.id.list);
class EndlessScrollListener implements OnScrollListener {
private int i = 0;
private int visibleThreshold = 5;
private int previousTotal = 0;
private boolean loading = true;
public EndlessScrollListener() {
}
public EndlessScrollListener(int visibleThreshold) {
this.visibleThreshold = visibleThreshold;
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if ((firstVisibleItem + visibleItemCount) == totalItemCount) {
new loadComments().execute();
mainListView.smoothScrollToPosition(0);
}
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
}
mainListView.setOnScrollListener(new EndlessScrollListener());
推荐答案
你试试这个:
public class Comment {
String username;
String content;
String number;
}
类适配器:
public class CommentAdapter extends BaseAdapter {
private List<Comment> listComment;
private Context context;
public CommentAdapter(List<Comment> listComment, Context context) {
super();
this.listComment = listComment;
this.context = context;
}
@Override
public int getCount() {
return listComment.size();
}
@Override
public Comment getItem(int position) {
return listComment.get(position);
}
@Override
public long getItemId(int arg0) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater mInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = mInflater.inflate(R.layout.comment_item, null);
}
final TextView textViewUsername = (TextView) v
.findViewById(R.id.comment_Username);
final TextView textViewNumber = (TextView) v
.findViewById(R.id.comment_number);
final TextView textViewContent = (TextView) v
.findViewById(R.id.comment_Content);
final String username = listComment.get(position).getUsername();
final String number= listComment.get(position).getNumber();
String content = listComment.get(position).getContent();
textViewUsername.setText(username);
textViewNumber.setText(number);
textViewContent.setText(content);
return v;
}
}
当您需要向列表添加新评论时.只需创建新评论并添加到listComment(listComment.add(newComment))，然后调用adapter.notifyDataSetChanged();
When you need to add new comment to list. just create new Comment and add to listComment(listComment.add(newComment)), after that, call adapter.notifyDataSetChanged();
这篇关于如何将数据添加到 listView 的自定义 BaseAdapter - Android的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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