Replace certain string's values dynamically

Question

I have a HashMap<Integer, Double> which looks something similar like this: {260=223.118,50, 261=1889,00, 262=305,70, 270=308,00}

From database I take a string that could look something like this: String result = "(260+261)-(262+270)";

I want to change the string's values of 260, 261, 262... (which are always the same with the HashMap's keys) with the values so I could get a string like: String finRes = "(223.118,50+1889,00)-(305,70+308,00)";

Also the string result can contain multiplication and division characters.

what did you try? Why are mathematical expression stored in the DB (and not the result) — user180100
– user180100, Commented Oct 9, 2017 at 16:25
It is very complicated to explain this, sorry. The explanation above was enough and the answers below seem to be very promising. I am going to test them as soon as I get access to the code. — gvlkn
– gvlkn, Commented Oct 9, 2017 at 16:49

Tim Biegeleisen · Accepted Answer · 2017-10-09 17:01:33Z

1

A simple regex solution here would be to match your input string against the pattern (\d+). This should yield all the integers in the arithmetic string. Then, we can lookup each match, converted to an integer, in the map to obtain the corresponding double value. Since the desired output is again a string, we have to convert the double back to a string.

Map<Integer, Double> map = new HashMap<>();
map.put(260, 223.118);
map.put(261, 1889.00);
map.put(262, 305.70);
map.put(270, 308.00);

String input = "(260+261)-(262+270)";
String result = input;
String pattern = "(\\d+)";

Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(input);
StringBuffer sb = new StringBuffer();

while (m.find()) {
    m.appendReplacement(sb, String.valueOf(map.get(Integer.parseInt(m.group(1)))));
}
m.appendTail(sb);
System.out.println(sb.toString());

Output:

(223.118+1889.0)-(305.7+308.0)

Demo here:

Rextester

edited Oct 9, 2017 at 17:01

answered Oct 9, 2017 at 16:28

Tim Biegeleisen

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Comments

Mohamed Ali RACHID · Accepted Answer · 2017-10-09 16:29:52Z

0

here is an explained solution:

    // your hashmap that contains data
    HashMap<Integer,Double> myHashMap = new HashMap<Integer,Double>();
    // fill your hashmap with data ..
    ..
    // the string coming from the Database
    String result = "(260+261)-(262+270)";
    // u will iterate all the keys of your map and replace each key by its value
    for(Integer n : myHashMap.keySet()) {
        result = result.replace(n,Double.toString(myHashMap.get(n)));
    }
    // the String variable 'result' will contains the new String

Hope it helps :)

answered Oct 9, 2017 at 16:29

Mohamed Ali RACHID

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2 Comments

user180100 Over a year ago

This could lead to some "Oh no!" for example if the string contains 160 and the map has a 16 key

Mohamed Ali RACHID Over a year ago

yes i agree with u Mr @RC. .. , i didn't expect this case , so the answer have to be deleted :) , in general i think that he has to try to code first then post the question to get a better solution

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