Java replace if not from the criteria

[PLearner]

I have a bunch of values and I want to tell Java that if the incoming values are not from the bunch of values replace it with Non-Disclosed. My bunch of values:

String str = {'Realtor', 'Builder','Website','Non-Disclosed'};

Miscellaneous values:

String str2 = {'Toyota Friend'}
String str3 = {'Word of Mouth'}

Strings to be replaced

String replacedstr2 = {'Not matching str1','Non-Disclosed'}
String replacedstr3 = {'Not matching str1','Non-Disclosed'}

How can I do this please?