Check parameter string Java regex

Question

I have two string types:

First : key1=value1&key2=value2&key3=value3...

Second : key1=value

How can I use a Java regular expression to check whether a string is of the first or second type? Example:

String str1 = "a=1&b=2"; // true
String str2 = "a=1&"; // false
String str3 = "a=1"; // true

Are there escape characters you have to take into account? Can = be part of a value? Can & be part of a key? — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Mar 5, 2014 at 18:17
Clippy says: It looks like you are trying to process GET request parameters. Would you like me to show you the normal ways of doing that rather than rolling your own? — Dave Newton
– Dave Newton, Commented Mar 5, 2014 at 18:18
The temptation is to go for the easy rep points by posting ([^=&]+=[^=&]+&)*[^=&]+=[^=&]+ as an answer, but it's unlikely to be the best thing to do in this case. — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Mar 5, 2014 at 18:22

Sabuj Hassan · Accepted Answer · 2014-03-05 18:21:36Z

1

Assuming the values are only alphanumeric characters.

String text = "a=1&b=2";
boolean match = text.matches("[a-zA-Z0-9]+=[a-zA-Z0-9]+(&[a-zA-Z0-9]+=[a-zA-Z0-9]+)*");

answered Mar 5, 2014 at 18:21

Sabuj Hassan

39.7k14 gold badges83 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1