Question

public ArrayList<HashMap<String,String>> c_tmp= new ArrayList<HashMap<String,String>>();
public HashMap<String,String>mapa=new HashMap<String, String>();
String[] name_Val = null;

//i fill the map and the array list in a while()

mapa.put(numberz,nnn);
c_tmp.add(mapa);

and an error occurs( force close)when trying to fill the next line name_Val=….

name_Val = (String[]) c_tmp.toArray(new String[c_tmp.size()]);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_dropdown_item_1line,name_Val);
txtPhoneName.setAdapter(adapter);

/// am I writing that line wrong ( because i’ve copied it from ArrayList<String>)

Answer 1

You should try to do it first with a map and when you initialize it then to hash map, and use a simple adapter

mAdapter = new SimpleAdapter(this, peopleList, R.layout.row ,new String[] 
           { "Name", "Phone"  }, new int[] { R.id.text1, R.id.text2  });
txtPhoneName.setAdapter(mAdapter);

But before all in another function populate the list of people…