使用正则表达式查找字符串以$符号开头

Question

String str = "hai ${name} .... Welcome to ${sitename}....";

from this str i need to replace ${name} by "jack" and ${sitename} by "google"

is it possible to do with regular Expression ?

or

is there any other fastest way to replace the string .

EDITED :

name and sitename is the str variable is dynamic .

1.So first i have to find the key .
Eg : here name , sitename is the key
2.Then i have an Hashmap which has key value pairs .
based on the key value i have to replace the string in str variable.

Answer 1

import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Replacer
{
    public static String replacePlaceHolders(String text)
    {
        Map<String, String> fields = new HashMap<>();

        fields.put("name", "jack");
        fields.put("sitename", "google");

        Pattern p = Pattern.compile("\\$\\{(.*?)\\}");
        Matcher matcher = p.matcher(text);

        StringBuffer result = new StringBuffer();

        while (matcher.find()) {
            String key = matcher.group(1);

            if (!fields.containsKey(key)) {
                continue;
            }

            matcher.appendReplacement(result, fields.get(key));
        }

        matcher.appendTail(result);

        return result.toString();
    }

    public static void main(String[] args)
    {
        System.out.println(
                replacePlaceHolders("hai ${name} .... Welcome to ${sitename}...."));
    }
}

Answer 2

NO Regex is needed!

You could iterate the keySet of your map, and do:

str=str.replace("${"+key+"}", map.get(key));

about the method:

http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#replace(java.lang.CharSequence , java.lang.CharSequence)

Answer 3

我认为你最好使用String.format

String str = String.format("hai %s .... Welcome to %s....", name, site);

Answer 4

Maybe this will help you:

\$\{name+\}

change ${name} to test

-> ${name} trete ${sitename} -> test trete ${sitename}

You have to escape this expression for usage in Java:

\\$\\{name+\\}

Answer 5

If you can replace ${name} and ${sitename} with {0} and {1} you could use MessageFormat .

String str = "hai {0} .... Welcome to {1}....";
String output = MessageFormat.format(str, new String[]{"jack","google"});