Question

public void onCreate(Bundle savedInstanceState) 
{
    teachersData=new TeachersData(this);  


    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    ArrayList<Data> classid=teachersData.listClass();
    ArrayAdapter<Data> adapter = new ArrayAdapter<Data>(this, android.R.layout.simple_list_item_1, classid);
    setListAdapter(adapter);

---

                   public void onClick(DialogInterface dialog, int id) {
                        String className = edit.getText().toString();
                        teachersData.insert(null, className, 0, 0, null);
                        Toast.makeText(getBaseContext(), className + " Added.", Toast.LENGTH_LONG).show(); 
                        dialog.cancel();
                   }
               })

I presume it involves notifyDataSetChanged() from my searching so far but I can’t figure out how to implement it.

Answer 1

You call notifyDataSetChanged() at point you have updated the data and you want to display the new data. When you have the new data you do adapter = new ArrayAdapter<Data>(this, android.R.layout.simple_list_item_1, classid); (again) which means you are feeding the adapter with new data, and then you call notifyDataSetChanged() to make ListView repopulate with the new data.