android how to subtract string from given string

android how to subtract string from given string

i m getting string in button.text i want to display only specific
charecter only but when click show full value in toast how i will do that?
Button e01;
e01.setText(days[1]); // 2013/09/11
i want to display only 11
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.e01:
value = e01.getText().toString();
Toast.makeText(this, value, Toast.LENGTH_SHORT) .show();
//value=// 2013/09/11