private TextView txt_total;
     private TextView text_cost_code;
    private double itemamount = 0;
      private double itemquantity = 0;

itemamount = Double.parseDouble(text_cost_code.getText().toString());                                                    txt_total.setText(Double.toString(itemamount));
edit_qty_code.addTextChangedListener(new TextWatcher() {
public void onTextChanged(CharSequence s, int start, int before,
int count) {
// TODO Auto-generated method stub
if (!edit_qty_code.getText().toString().equals("")
|| !edit_qty_code.getText().toString().equals("")) {
itemquantity = Double.parseDouble(edit_qty_code.getText()
.toString());
itemamount = Double.parseDouble(text_cost_code.getText()
.toString());
txt_total.setText(Double                                                                                .toString(itemquantity * itemamount));
} else {
txt_total.setText("0.00");
}
}