replacing some static text with dynamic text using string builder

Question

I have a url which is generate on the fly and i want to place some text with unknowing text using string builder. Please let me know how?

Example:-

http://localhost/abcdef/servlet/cpd.abcd.build.coupons.CouponValueFormatterServlet?dsn=frd_abcdef&lang=ENG&val=PRCTXT|ABCDE_-1223344&classGroupid=101,201&fgcolor=000000&bgcolor=E0DBD8&width=100&height=80&fontSize=11&fontWeight=normal.

The above URL is a string builder and "val=PRCTXT|ABCDE_-1223344" text has to change with "val=123456" text. But here Val is always user input . so it is changing always.

Why are you focused on `StringBuilder`? It is not intended for what you're trying to do, so you're trying to use the wrong tool. — Andreas, Aug 03 '16 at 19:26
I would like to change the URL value with other value, which i know. — RKCY, Aug 03 '16 at 19:28
Possible duplicate of [Java: String formatting with placeholders](http://stackoverflow.com/questions/17537216/java-string-formatting-with-placeholders) — Jerod Johnson, Aug 03 '16 at 19:28
How can i split the string. this url is changing the number of the characters always..means dynamic url but " http://localhost/abcdef/servlet/cpd.abcd.build.coupons.CouponValueFormatterServlet?" is always same — RKCY, Aug 03 '16 at 19:29
I think regex might be desirable here, or, if you know that length of each inner part is always the same you can probably do a substring — SomeStudent, Aug 03 '16 at 19:34
we can replace with new string from "val= " and ending before "&classGroupid" . Is this possible, if know start and end strings to replace in between data. ? — RKCY, Aug 03 '16 at 19:36

score 0 · Accepted Answer · answered Aug 03 '16 at 19:41

If you absolute want to use StringBuilder, you should read the javadoc to find usable methods for your purpose.

That would be:

StringBuilder buf = new StringBuilder("http://localhost/abcdef/servlet/cpd.abcd.build.coupons.CouponValueFormatterServlet?dsn=frd_abcdef&lang=ENG&val=PRCTXT|ABCDE_-1223344&classGroupid=101,201&fgcolor=000000&bgcolor=E0DBD8&width=100&height=80&fontSize=11&fontWeight=normal.");

int start = buf.indexOf("&val=");
if (start != -1) {
    start += 5;
    int end = buf.indexOf("&", start);
    if (end == -1)
        end = buf.length();
    buf.replace(start, end, "123456");
    System.out.println(buf);
}

Thank you Andreas. Its working. – RKCY Aug 04 '16 at 13:40 — RKCY, Aug 04 '16 at 13:40

replacing some static text with dynamic text using string builder

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