adding data to existing listview

Question

I have created listview using the following code

public class homeScreen extends Activity{
    ArrayList<SingleRow> list;
    boolean flag = false;
    String space = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        final Context c = this;
        super.onCreate(savedInstanceState);
        setContentView(R.layout.homescreen);

        //putting actual values in array
        list = new ArrayList<SingleRow>();
        Resources res = c.getResources();
        String[] titles = res.getStringArray(R.array.titles);
        int[] images = {R.drawable.error,R.drawable.ic_launcher,R.drawable.ic_launcher};

        //putting single row in arraylist
        for(int i = 0;i<3;i++){
            list.add(new SingleRow(titles[i], images[i]));
        }

        final ListView list1 = (ListView)findViewById(R.id.spacelist);
        final MySimpleAdapter adapter = new MySimpleAdapter(this,list);
        list1.setAdapter(adapter);
        space = getIntent().getStringExtra("spaceName");
        if(null! = space){
            adapter.addView(space);
        }

        list1.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View v, int position, long id) {
                Resources res = c.getResources();
                String[] titles = res.getStringArray(R.array.titles); 

                 if((titles[position]).equalsIgnoreCase("My Ideas")){
                      Intent i = new Intent(homeScreen.this, privateSpaceList.class);
                      startActivity(i);

                 } else if((titles[position]).equalsIgnoreCase("Create New Space")){
                     Intent i = new Intent(homeScreen.this, createNewSpace.class);
                     startActivity(i);
                 }
            }
        });

    }
}

Row class:

class SingleRow{

    String title;
    int image;
    public SingleRow(String title,int image) {
        this.title = title;
        this.image = image;
    }
}

Adapter:

 class MySimpleAdapter extends BaseAdapter{

    ArrayList<SingleRow> list;
    private Context context;
    public MySimpleAdapter(Context c,ArrayList<SingleRow> list) {
        this.context = c;
        this.list = list;
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int i) {
        return list.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    public void addView(String space) {
        int rows = this.getCount();
        list.add(rows, new SingleRow(space,R.drawable.ic_launcher));
        notifyDataSetChanged();
    }

    @Override
    public View getView(int i, View view, ViewGroup viewgroup) {
        LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View row = inflater.inflate(R.layout.single_row,viewgroup,false);
        TextView title = (TextView)row.findViewById(R.id.label);
        ImageView image = (ImageView)row.findViewById(R.id.imageView);
        SingleRow temp = list.get(i);
        title.setText(temp.title);
        image.setImageResource(temp.image);
        return row;
    }   
}

code for create new space

public class createNewSpace extends Activity{
    Button add;
    TextView sname,pname;
    ListView plist;
    int success;
    Jparser jsonParser = new Jparser();
    JSONObject json;
    private ProgressDialog pDialog;
    ArrayList<String> usersList;
    ArrayList<String> spaceUsers;
    private static String url_users = "http://10.0.2.2/phpdata/getting_allusers.php";
    private static String url_create_space = "http://10.0.2.2/phpdata/create_space.php";
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_USERS = "users";
    private static final String TAG_UNAME = "firstName";

    // products JSONArray
    JSONArray users = null;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.createnewspace);

        sname=(TextView)findViewById(R.id.spaceName);
        pname=(TextView)findViewById(R.id.participents);
        plist=(ListView)findViewById(R.id.participantlist);
        add=(Button)findViewById(R.id.button1);
        // Hashmap for ListView
        usersList= new ArrayList<String>();
        spaceUsers=new ArrayList<String>();

        add.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                new getAllUsers().execute();
            }
        });
        plist.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                    long arg3) {
                // TODO Auto-generated method stub
                String users[]=usersList.toArray(new String[usersList.size()]);
                Toast.makeText(getApplicationContext(), "User "+users[arg2]+ " added to space "+sname.getText(), Toast.LENGTH_SHORT).show();        
                spaceUsers.add(users[arg2]);
            }
        });
        // Loading users in Background Thread
    }
    public boolean onCreateOptionsMenu(Menu menu) {
        // TODO Auto-generated method stub
        super.onCreateOptionsMenu(menu);
        getMenuInflater().inflate(R.menu.menuspace, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        return MenuChoice(item);
    }


    private boolean MenuChoice(MenuItem item)
    {
        switch(item.getItemId())
        {
            case R.id.create:
                new createSpace().execute();
                return true;

        }
        return false;
        }

    class createSpace extends AsyncTask<String, String, String> {

            /**
             * Before starting background thread Show Progress Dialog
             * */
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
            }


        @Override
        protected String doInBackground(String... arg0) {
            // TODO Auto-generated method stub      
            for(int i=0;i<spaceUsers.size();i++)
            {   
                String sname1 = sname.getText().toString();
                String uname = spaceUsers.get(i);

                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair("sname", sname1));
                params.add(new BasicNameValuePair("uname", uname));


            // getting JSON Object
            JSONObject json = jsonParser.makeHttpRequest(url_create_space,
                    "POST", params);
            Log.d("Create Response", json.toString());

            // check for success tag
            try {
                int success = json.getInt(TAG_SUCCESS);
                if (success == 1) {
                    // successfully inserted user details
                    Intent is = new Intent(getApplicationContext(), homeScreen.class);
                    is.putExtra("spaceName", sname1);
                    startActivity(is);
                    // closing this screen
                    finish();
                } else {
                }
            } catch (JSONException e) {
                e.printStackTrace();
                }
            }
            return null;
            }

        protected void onPostExecute(String file_url) {
            // dismiss the dialog once done
        }
    }

    class getAllUsers extends AsyncTask<String, String, String> {


        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected String doInBackground(String... arg0) {
            // TODO Auto-generated method stub
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            // getting JSON Object
            json = jsonParser.makeHttpRequest(url_users,"GET", params);
            // check log cat from response
            Log.d("Create Response", json.toString());

            // getting value of success tag
            try {
            success = json.getInt(TAG_SUCCESS);
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;    
        }

      protected void onPostExecute(String file_url) {

          if (success == 1) {
                // Getting Array of users
                try{
                JSONArray users=json.getJSONArray(TAG_USERS);
                // looping through All Products
                for (int i = 0; i < users.length(); i++) {
                    Log.d("check", "success");
                    JSONObject c = users.getJSONObject(i);

                    // Storing each json item in variable
                    String name = c.getString(TAG_UNAME);
                    Log.d("name....",name);
                    // adding HashList to ArrayList
                    usersList.add(name);
                }
            } catch(JSONException e)
            {
                e.printStackTrace();
            }
          }
            runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                         plist.setAdapter(new ArrayAdapter<String>(createNewSpace.this,android.R.layout.simple_list_item_1,usersList)); 
                }
            });
    }
    }

}

Now I want to add Item to this existing list. I am taking data from another activity using intent. Now one item get added.but next time that get replaced. Please Help. Thank you in advance.

Answer 1

You should move the creation of the data outside of the adapter:

list=new ArrayList<SingleRow>();
//putting actual values in array
Resources res=c.getResources();
String[] titles=res.getStringArray(R.array.titles);
int[] images={R.drawable.error,R.drawable.ic_launcher,R.drawable.ic_launcher};

//putting single row in arraylist
for(int i=0;i<3;i++){
    list.add(new SingleRow(titles[i], images[i]));
}

Pass the list variable to the adapter and store a reference to it there. Then you can just update the data in the list variable, and call notifyDataSetChanged() on your adapter.

Edit: It seems you want to store the space values, and then retrieve them in the HomeScreen activity later. If I understand the flow of your app correctly, then the createNewSpace class should store the space in SharedPreferences. Then in the HomeScreen activity you should retrieve those from the SharedPreferences, and show them.

Answer 2

You can add data to the adapter and call notifyDataSetChanged().Alternatively, You can create a new adapter and listView.setAdapter(adapter) that adapter.