Replace a variable in a String

Question

I am looking for a String Utils so that I can do something like this.

String input = "this is the $var on $date"
someUtil.evaluate(input, [var: "end", date: "11/11/11"])

output : this is the end on 11/11/11.

someUtil.evaluate(input, [var: "start", date: "10/10/10"])

output : this is the start on 10/10/10.

havent used spring classes for any string manipulation. Surprisingly there is class for StringUtils (docs.spring.io/spring-framework/docs/3.2.0.M1/api/org/…). But Even they suggest use of apache common api — Saurabh
– Saurabh, Commented Dec 2, 2015 at 6:54
You could probably implement on your own using Map and String.replaceFirst(regex, replacement) — Leet-Falcon
– Leet-Falcon, Commented Dec 2, 2015 at 6:54
Why do you need to use a Spring utility? Can't you use SimpleDateFormat? System.out.println(new SimpleDateFormat("yy/MM/dd").format(new Date())); — user1766169
– user1766169, Commented Dec 2, 2015 at 6:59
@saurabh Thanks apache common StrSubstitutor solves the problem — R. S.
– R. S., Commented Dec 2, 2015 at 7:03

Ralph · Accepted Answer · 2015-12-02 08:32:21Z

5

Use standard java MessageFormat, it is quite powerfull (read its class level JavaDoc)

Date endDate = new GregorialCalendar(2011, Calendar.NOVEMBER, 11).getTime();
...
MessageFormat.format(
      "this is the {0} on {1,date,yy/MM/dd}",
      new Object[]{"end", endDate});

answered Dec 2, 2015 at 8:32

Ralph

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xxxvodnikxxx · Accepted Answer · 2015-12-02 09:17:48Z

Do you really need as incoming parameter that "array" ? If not, that you can implement as easy as it is ..

private static String replaceVarByVal(String toReplace,String var,String val){
        return toReplace.replace(var, val);
}

(You can easy modify that to incom params arrays, but better should be eg. Map- key variable, value new value of the "placeholder" - $var)

Arrays variant:

private static String replaceVarByVal(String toReplace,String[] var,String[] val){
        String toRet = toReplace;
        //arrays logic problem 
        if(var.length != val.length){
            return null;
        }else{
            for (int i = 0; i < var.length; i++) {
                toRet = toRet.replace(var[i], val[i]);
            }
        }
        return toRet;
}

Better variant with map:

private static String replaceVarByVal(String toReplace,Map<String, String> paramValsMap){
        String toRet = toReplace;
        for (Map.Entry<String, String> entry : paramValsMap.entrySet())
        {
            toRet=toRet.replace(entry.getKey(), entry.getValue());
        }
        return toRet;
}

(And that can be used universally for anything)

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