Java: Regular expression to strip out: %j or %f

Is there an easy way to strip out something like %j or %f out of a string and replace it with an int? like:

XYZ: %J开发者_如何学Python Num: %f

becomes

XYZ: 12 Num: 34

---

A simple way would be:

"XYZ: %J Num: %f".replace("%J", "12").replace("%f", "34");

---

import java.util.Enumeration;
import java.util.Hashtable;

public class BasicReplace {

    public static void main(String[] args) {
        Hashtable<String, Integer> values = new Hashtable<String, Integer>();
       values.put("%J", 3);
       values.put("%F", 5);
       values.put("%E", 7);
        String inputStr = "XYZ: %J ABC: %F";
        String currentKey;
        Enumeration<String> enume = values.keys();
        while(enume.hasMoreElements()){
            currentKey = enume.nextElement();
            inputStr = inputStr.replaceAll(currentKey, String.valueOf(values.get(currentKey)));
        }
        System.out.println(inputStr);
        System.out.println("XYZ: %J Num: %f".replace("%J", "12").replace("%f", "34"));
    }
}

TUNDUN ! :D
Well, it might not exactly be "an easy way", but it works.

---

If you want to do this reliably you should also take into consideration that %J might be prefixed with a % character, in which case %J should not be replaced. E.g.

XYZ: %J Num: %f. %%Just like I told you%%

which should then print as

XYZ: 12 Num: 34. %Just like I told you%

So I do not think regular expressions can be used for this. You need to keep track of states, something simple like outlined in my answer here.

---

Maybe you in fact want to use the java.util.Formatter class or it's wrapper methods everywhere in the library?

"XYZ: %Y Num: %f".format(new Date(), 30)

should give "XYZ: 2011 Num: 30.000000". Hmm, does not look like you want this, though ...