You can check using the TextUtils class like
TextUtils.isEmpty(ed_text);
or you can check like this:
EditText ed = (EditText) findViewById(R.id.age);
String ed_text = ed.getText().toString().trim();
if(ed_text.isEmpty() || ed_text.length() == 0 || ed_text.equals("") || ed_text == null)
{
//EditText is empty
}
else
{
//EditText is not empty
}