Unable to extract string using this regex expression in java

Question

I have a string whose first character is "^". I want to extract the string without this character. For eg : "^coal" should become "coal". Following is the code I wrote, but I don't know why it's not working.

public void RegEx(String s1){
        System.out.println(s1.substring(0,1));  //to check if i am ok.
        if((s1.substring(0,1)).equals("^")){
            Pattern p = Pattern.compile("^");
            String[] extracted = p.split(s1);
            for(String s: extracted){
                System.out.println(s);
            }
        }
    }

s1 = "^coal". Output = "^coal".

I'm not a javascript expert, but if you're trying to remove the first character, can't you just do s1 = s1.substring(1); inside your if statement? For example, "MyString".substring(1); evaluates to "yString" — Tyler Roper
– Tyler Roper, Commented Aug 14, 2016 at 6:15
This is just a fragment of a larger problem. So I really need to know the official way. Thanks though. — Uddipta_Deuri
– Uddipta_Deuri, Commented Aug 14, 2016 at 6:18

Erwin Bolwidt · Accepted Answer · 2016-08-14 06:18:26Z

5

The ^ character has special meaning in a regex so you need to escape it: "\\^".

But a regex is not the most efficient way to do this. Just use substring:

if (s1.startsWith("^")) {
    s1 = s1.substring(1);
}
System.out.println(s1);

Note: as you see above you can also use startsWith to easily check if a string starts with some other string.

edited Aug 14, 2016 at 6:18

answered Aug 14, 2016 at 6:17

Erwin Bolwidt

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1 Comment

Tyler Roper Over a year ago

Knew I shoulda posted my comment as an answer :) +1!

Elliott Frisch · Accepted Answer · 2016-08-14 06:15:28Z

1

The character ^ is significant in a regular expression. Escape it like,

Pattern p = Pattern.compile("\\^");

answered Aug 14, 2016 at 6:15

Elliott Frisch

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Comments

shaifali Gupta · Accepted Answer · 2016-08-14 06:16:55Z

0

Use this using indexOf method. It is short and more efficient

 String s="^coal";
 int l=s.indexOf("^");
 System.out.println(s.substring(l+1));

answered Aug 14, 2016 at 6:16

shaifali Gupta

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