Turning Edit Fields into Password Fields
You need to designate an EditText as a password field, so that characters the user types will not be visible to "shoulder surfers".
Android provides the password attribute on EditTexts
You might wish to provide a login screen in your application. This would require a username and a password field. While the password field would be an EditText, it should be modified a little bit. It should hide the characters after they are typed. This can be done by adding a property to the EditText in XML:
With this new property, this is how the EditText in which password is being entered, looks: