按下后退按钮时刷新listview-android

Question

sir, how do i refresh my listview if i pressed the back button in android emulator? i've clicked an item on activityA then goes to an edit form in activityB. after saving updates, if i pressed the back button, it should refresh the list.

here is my activityA

public class CustomListView extends Activity {
final Context context = this;
public static String name;
public static String number;
int REQUEST_CODE = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    GroupDb info = new GroupDb(this);
    info.open();
    ArrayList<Contact> searchResults = info.getView();

    MyCustomBaseAdapter mcba = new MyCustomBaseAdapter(CustomListView.this, searchResults);
    mcba.updateResults(searchResults);
    final ListView lv = (ListView) findViewById(R.id.srListView);
    lv.setAdapter(new MyCustomBaseAdapter(this, searchResults));

    info.close();

    lv.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> a, View v, int position, long id) {
            // TODO Auto-generated method stub
            Object o = lv.getItemAtPosition(position);
            final Contact fullObject = (Contact)o;
            AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);
            alertDialogBuilder
            .setMessage("Select action")
            .setCancelable(false)
            .setPositiveButton("Edit", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int id) {
                    Toast.makeText(getApplicationContext(), "Edit ", Toast.LENGTH_LONG).show();
                    name = fullObject.getName();
                    number = fullObject.getPhoneNumber();
                    Intent intent = new Intent();
                    intent.setClass(CustomListView.this, EditDetails.class);

                    startActivityForResult(intent, REQUEST_CODE);

                }
              })

             .setNeutralButton("Delete", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int id) {
                    Toast.makeText(getApplicationContext(), "Delete ", Toast.LENGTH_LONG).show();

                }
              }) 
            .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    // if this button is clicked, just close
                    // the dialog box and do nothing
                    dialog.cancel();
                }
            });

            // create alert dialog
            AlertDialog alertDialog = alertDialogBuilder.create();

            // show it
            alertDialog.show();
        }

    });
}
public void onResume()
{  // After a pause OR at startup
super.onResume();
//Refresh your stuff here
GroupDb info = new GroupDb(this);
info.open();
ArrayList<Contact> searchResults = info.getView();

MyCustomBaseAdapter mcba = new MyCustomBaseAdapter(CustomListView.this, searchResults);
mcba.updateResults(searchResults);

info.close();
}

protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
    super.onActivityResult(requestCode, resultCode, intent);

    if (requestCode == REQUEST_CODE) {
        GroupDb info = new GroupDb(this);
        info.open();
        ArrayList<Contact> searchResults = info.getView();

        MyCustomBaseAdapter mcba = new MyCustomBaseAdapter(CustomListView.this, searchResults);
        mcba.updateResults(searchResults);

        info.close();
    }
}
//edit or delete list when clicked
public void deleteEditOption()
{

}//end deleteEditOption()
}

and here is my activityB

public class EditDetails extends Activity{
public String nameChanged;
public String numChanged;
public String name;
public String num;
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.editdetails);
    final EditText sqlName = (EditText)findViewById(R.id.editName);
    final EditText sqlNumber = (EditText)findViewById(R.id.editNumber);
    name = CustomListView.name;
    num = CustomListView.number;
    Button bUpdate = (Button)findViewById(R.id.editUpdate);
    Button bView = (Button)findViewById(R.id.editView);
    sqlName.setText(name);
    sqlNumber.setText(num);

    bUpdate.setOnClickListener(new OnClickListener() {

        public void onClick(View arg0) {
            nameChanged = sqlName.getText().toString();
            numChanged = sqlNumber.getText().toString();
            GroupDb info = new GroupDb(EditDetails.this);
            info.open();
            long rowid = info.getRowId(name, num);
            info.updateNameNumber(rowid+1, nameChanged, numChanged);
            Toast.makeText(getApplicationContext(), rowid+" "+nameChanged+" "+numChanged, Toast.LENGTH_LONG).show();
            ArrayList<Contact> searchResults = info.getView();
            MyCustomBaseAdapter mcba = new MyCustomBaseAdapter(EditDetails.this, searchResults);
            mcba.updateResults(searchResults);
            Toast.makeText(getApplicationContext(), "Update Successful!", Toast.LENGTH_LONG).show();
            info.close();
            }
        });
    bView.setOnClickListener(new OnClickListener() {

        public void onClick(View arg0) {
            Intent intent = new Intent();
            intent.setClass(EditDetails.this, CustomListView.class);

            startActivityForResult(intent, 0);
            }
        });
}

}

if i clicked this bView button in my activityB, it updates the listview. but pressing the back button just shows my previous unupdated listview. thanks for help in advance

edit

public class MyCustomBaseAdapter extends BaseAdapter {
private static ArrayList<Contact> searchArrayList;

private LayoutInflater mInflater;

public MyCustomBaseAdapter(Context context, ArrayList<Contact> results) {
    searchArrayList = results;
    mInflater = LayoutInflater.from(context);
}

public void updateResults(ArrayList<Contact> results) {
    searchArrayList = results;
    //Triggers the list update
    notifyDataSetChanged();
}

public int getCount() {
    return searchArrayList.size();
}

public Object getItem(int position) {
    return searchArrayList.get(position);
}

public long getItemId(int position) {
    return position;
}

public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.custom_row_view, null);
        holder = new ViewHolder();
        holder.txtName = (TextView) convertView.findViewById(R.id.name);

        holder.txtPhone = (TextView) convertView.findViewById(R.id.phone);

        holder.status = (TextView) convertView.findViewById(R.id.status);
        convertView.setTag(holder);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    holder.txtName.setText(searchArrayList.get(position).getName());

    holder.txtPhone.setText(searchArrayList.get(position).getPhoneNumber());

    holder.status.setText(searchArrayList.get(position).getStatus());

    return convertView;
}

static class ViewHolder {
    TextView txtName;
    TextView txtPhone;
    TextView status;
}

}

Answer 1

Rewrite

While I recommend customizing a CursorAdapter to work with your database. Let's change a couple points with your current code:

First create a field variable for mbca , (just like name and number ).

MyCustomBaseAdapter mcba;

Second update how you initialize mbca in onCreate() :

mcba = new MyCustomBaseAdapter(EditDetails.this, searchResults);
//mcba.updateResults(searchResults); this line isn't necessary here

Third make a small change to onResume() :

public void onResume()
{  // After a pause OR at startup
    super.onResume();
    //Refresh your stuff here
    GroupDb info = new GroupDb(this);
    info.open();
    mcba.updateResults(info.getView());
    info.close();
}

This works because updateResults() calls notifyDataSetChanged() and this updates the ListView automatically.