How to add data to custom BaseAdapter for listView

问题:

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());

回答1:

You try this :

public class Comment {
String username;
String content;
String number;
 }

Class Adapter:

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;
}

}

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();

回答2:

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;
        }
    }

}