I have a set of radio buttons in an Android application. How would I indicate to the user that a radio-button is required?

Is there a default Android way for it?

EDIT: Selecting the default value is not possible, since selecting the wrong one is crucial in my situation. The user should choose one option and only one.

The user should see, that one option is required, BEFORE he tries to send the content. Red Background or frame are the usual solution in Web forms. What's usual in Android?

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2 Answers 2


Why don't you select one of the two radio buttons by default?

Having a radio buttons group with no selection is an edge case, the user won't be able to restore the initial state once a button is selected.

  • 2
    +1, although it is sometimes required not to preselect any option for legal and other reasons -- e.g. if an insurance company asks 'do you want to be insured for X?', explicit consent is required either way.
    – Brendon
    Jul 29, 2013 at 15:56
  • From the context the choice doesn't seem a critical one "To the left" / "To the right" is probably just a layout option, not a legal agreement... Jul 29, 2013 at 16:00
  • Indeed this is such a case. This example is just a simplified summary of my situation, where I am not able to select a default value, since selecting the wrong one would be crucial - I will let the user choose one.
    – Skip
    Jul 30, 2013 at 5:48
  • 1
    @Brendon besides, that's when you'd use a check-box.
    – Dirk v B
    Jul 30, 2013 at 6:04

Technical Answer: You should be able to use the setError method on your radio buttons.

Here is the setError on a textbox:


More Information:

http://www.donnfelker.com/android-validation-with-edittext/ https://stackoverflow.com/questions/9189424/set-error-android https://stackoverflow.com/questions/10819409/checkbox-error-dont-disappears-after-checking

UX Answer: It is preferable to have a default option selected in a group of radio buttons. There are some instances not to have a default, but really think about what you are asking, and consider if a default or another set of controls would be more appropriate.

See this excerpt from MSDN:

Default values

Because a group of radio buttons represents a set of mutually exclusive choices, always have one radio button selected by default. Select the safest (to prevent loss of data or system access) and most secure and private option. If safety and security aren't factors, select the most likely or convenient option.

Exceptions: Don't have a default selection if:

  • There is no acceptable default option for safety, security, or legal reasons and therefore the user must make an explicit choice. If the user doesn't make a selection, display an error message to force one.

  • The user interface (UI) must reflect the current state and the option hasn't been set yet. A default value would incorrectly imply that the user doesn't need to make a selection.

  • The goal is to collect unbiased data. Default values would bias data collection.
  • The group of radio buttons represents a property in a mixed state, which happens when displaying a property for multiple objects that don't have the same setting. Don't display an error message in
    this case since each object has a valid state.

Make the first option the default option, since users often expect that—unless that order isn't logical. To do this, you might need to change the option labels.

Also, the button should be on the left, with the text on the right.

  • I would like to let the user know, that the radiobutton is required BEFORE he tries to enter or send something. Maybe via a red BG?
    – Skip
    Jul 30, 2013 at 5:52

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