Validating IP never succeeds

Question

The user enters an IP address in a EditTextPreference and I try to validate the IP with this code:

private EditTextPreference ipPref;
private Matcher matcher;
private SharedPreferences settings;
private final Pattern IP_ADDRESS
    = Pattern.compile(
    "((25[0-5]|2[0-4][0-9]|[0-1][0-9]{2}|[1-9][0-9]|[1-9])\\.(25[0-5]|2[0-4]"
    + "[0-9]|[0-1][0-9]{2}|[1-9][0-9]|[1-9]|0)\\.(25[0-5]|2[0-4][0-9]|[0-1]"
    + "[0-9]{2}|[1-9][0-9]|[1-9]|0)\\.(25[0-5]|2[0-4][0-9]|[0-1][0-9]{2}"
    + "|[1-9][0-9]|[0-9]))");

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.settings);

    //PREF_IP is the android:key of the EditTextPreference
    ipPref = (EditTextPreference) getPreferenceManager().findPreference("PREF_IP"); 
    settings = PreferenceManager.getDefaultSharedPreferences(this);
    matcher = IP_ADDRESS.matcher(settings.getString("PREF_IP", "0.0.0.0"));

ipPref.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {            
        public boolean onPreferenceChange(Preference preference, Object newValue) {

            try 
            {
                if(matcher.matches()){
                    Log.d("settings", "matches!");
                    return true;
                }else{
                    Log.d("settings", "doesn't match!");
                    return false;
                }
            }
            catch(Exception e)
            {
                return false;
            }
        }
    }); 
}

If I enter a valid IP address the code never sees it as valid and the log says "doesn't match!". What am I doing wrong?

You should create your matcher in the method `onPreferenceChange()` instead of creating it upfront. — Guillaume Polet, Jun 20 '15 at 10:33
Yes it changes everything. But im not sure your regexp is correct — Guillaume Polet, Jun 21 '15 at 10:30
@GuillaumePolet : I tried it and the behaviour doesn't change... that was I meant. The regex should be ok, I got it from https://stackoverflow.com/questions/3698034/validating-ip-in-android — glass, Jun 21 '15 at 10:38
Don't know the exact internals of Android, but if you use someting like this in the onPreferenceChange() method,it should work: `IP_ADDRESS.matcher(newValue.toString()).matches()` — Guillaume Polet, Jun 21 '15 at 19:25
That's correct! I was stupid to not take care of the Object newValue! Add your answer if you want me to accept it. Thank you! — glass, Jun 22 '15 at 08:16

Guillaume Polet · Accepted Answer · 2015-06-22T19:54:48.817

1

Change your test in the onPreferenceChange() method, to:

 IP_ADDRESS.matcher(newValue.toString()).matches()

edited Jun 22 '15 at 19:54

answered Jun 22 '15 at 11:04

Guillaume Polet

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Validating IP never succeeds

1 Answers1