我有一个自定义的BaseAdapter类，可以为注释，用户名和数字创建视图。此BaseAdapter从An AsyncTask接收此信息。 AsyncTask在用户到达listView的底部时运行。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，只需将数据添加到listView的底部。所有这些类都在同一个Activity中。这是我目前的代码。
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());
答案 0 :(得分：6)
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。只需创建新的注释并添加到listComment（listComment.add（newComment）），然后调用adapter.notifyDataSetChanged（）;
答案 1 :(得分：0)
package com.example.baseadapter;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity implements OnItemClickListener {
public static final String[] title = new String[] {
"image 1", "image 2", "image 3", "image 4"
};
public static final Integer[] images = {
R.drawable.aa, R.drawable.bb, R.drawable.cc, R.drawable.cc, R.drawable.dd
};
ListView listview;
List<RowItem> rowItems;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
rowItems = new ArrayList<RowItem>();
for (int i = 0; i < title.length; i++) {
RowItem item = new RowItem(images[i], title[i]);
rowItems.add(item);
}
listview = (ListView)findViewById(R.id.listview);
customBaseAdapter cba = new customBaseAdapter(this, rowItems);
listview.setAdapter(cba);
listview.setOnItemClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
Toast.makeText(getApplicationContext(), "item selected", Toast.LENGTH_LONG).show();
}
public class customBaseAdapter extends BaseAdapter {
Context context;
List<RowItem> rowItem;
public customBaseAdapter(Context context, List<RowItem> listItem) {
this.context = context;
rowItem = listItem;
Log.d("const", "const");
}
@Override
public int getCount() {
Log.d("count", "count");
return rowItem.size();
}
@Override
public Object getItem(int arg0) {
Log.d("item", "item");
return rowItem.get(arg0);
}
@Override
public long getItemId(int position) {
Log.d("const", "item id");
return rowItem.indexOf(getItem(position));
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Log.d("const", "getview");
LayoutInflater inflater = (LayoutInflater)context
.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
RowItem rowitem = (RowItem)getItem(position);
TextView textForTitle;
ImageView imgForImage;
convertView = inflater.inflate(R.layout.inflate, null);
textForTitle = (TextView)convertView.findViewById(R.id.textview);
imgForImage = (ImageView)convertView.findViewById(R.id.imageview);
textForTitle.setText(rowitem.getTitle());
imgForImage.setImageResource(rowitem.getImageId());
return convertView;
}
}
public class RowItem {
int imageId;
String title;
public RowItem(int imageId, String title) {
this.imageId = imageId;
this.title = title;
}
public int getImageId() {
return imageId;
}
public void setImageId(int imageId) {
this.imageId = imageId;
}
public String getTitle() {
return title;
}
public void setStringTitle(String title) {
this.title = title;
}
@Override
public String toString() {
return title;
}
}
}