Regular expression to take last word in a string

[Raja Mirrah]

Hi all,
I have a requirement wherein i have to take the last word which in coming in a string.

Ex:

I have a string in below format

String Str = "2009-08-05T15:07:12-04:00#2009-08-05 15:07:09 EDT: Failed or Error in Loopback for OCU"

I have to take the word OCU from the given string

Note: I donot know what string is coming as input and only thing i know is i have to take the last word in the string in this case the last word is OCU.

I am trying to use the regular expression in replaceFirst method.


Can anyone give me regex which will satisfy my requirement?

Early response is highly appreciated!!!

Warm Regards,
Raj

[Gerardo Tasistro]

Assuming the word separator is space " " (as it usually is). The following code works fine:

    
		String data="2009-08-05T15:07:12-04:00#2009-08-05 15:07:09 EDT: Failed or Error in Loopback for OCU" ;
		String[] dataRows=data.split(" ");
		System.out.println(dataRows[dataRows.length-1]);

[Antany Vasanth]

Hello Raja,

Regular expression is very powerfull tool to handle various string manipulation/parsing etc. Use it when its really required.

You can simply do it using some basic String methods.

str = str.substring(str.trim().lastIndexOf(" ")+1,str.trim().length())

The above code just finds the last space and then get the remaining string.

Incase if you want to use regular expression use the following code to match the last string

                        String str = "asdf asdf  asd12f1 ";
		Pattern p = Pattern.compile("\\s(\\w+)$");
		Matcher m = p.matcher(str.trim());
		while(m.find()){
			System.out.println( m.group());
		}

The above regular expression also uses the same logic to findout the last word. It just looks for the space followed by any word and that should be last one.

Regards,
Antany

[Raja Mirrah]

Thanks for your reply Antany,

Even i have done it using String Function as you said using lastIndex.

But Since regex is powerful, i thought of doing it . Anyways Thank you so much.....

[Roldan Baldo]

it can be done also like this:

 . . .
String word= "asdf fds asd fada";
String lastWord="";
for(int i=word.length()-1;i>=0;i--){
    if(word.charAt(i)==" "){
        break;
    }
    lastWord += word.charAt(i);
}
String finalLastWord = "";
for(int i=lastWord.length()-1;i>=0;i--){
    finalLastWord += lastWord.charAt(i);
}

System.out.println("Last word is: "+finalLastWord);
 . . .

you can try many different ways. have fun.

[Campbell Ritchie]

Welcome to JavaRanch Roldan Baldo. Please use the CODE button; I have edited your post so you can see how much better it looks.

[Rob Spoor]

Not quite efficient, Roldan. Apart from the compiler error when comparing a char to a String (you should use '' instead of ""), multiple String concatenations should be prevented (single line String concatenations are ok). Use a StringBuilder instead. It also has a built-in reverse operator:

 . . .
String word= "asdf fds asd fada";
StringBuilder sb = new StringBuilder(word.length());
for (int i = word.length() - 1; i >= 0; i--)
{
    char c = word.charAt(i);
    if (Character.isWhitespace(c)) // better since it also handles \r and \n
    {
        break;
    }
    sb.append(c);
}
sb.reverse();
String lastWord = sb.toString();
System.out.println("Last word is: "+finalLastWord);
 . . .

Now ideally you wouldn't replace but insert the char at position 0, but that can be quite bad for performance if the last word is long - it needs to shift elements in its internal array all the time.

[anandhi mohan]

Try This,

   
String input="abcd scd xsdcsc efgh";
        input = input.trim();
        Pattern p=Pattern.compile("(?<=\\s)[\\w]+$");
        Matcher m=p.matcher(input);
        if(m.find())
        {
            System.out.println("output:"+m.group());
        } 

[Roldan Baldo]

wow! thanks rob and campbell.

i thought it is ok to compare string in my post because there is no compile error. thanks to the comment in my code, now the code is more specific.

i just want to be part of javaranch.

[Henry Wong]

Raja Mirrah wrote:
String Str = "2009-08-05T15:07:12-04:00#2009-08-05 15:07:09 EDT: Failed or Error in Loopback for OCU"

I have to take the word OCU from the given string

...

I am trying to use the regular expression in replaceFirst method.

Since the OP requested that the solution use the replaceFirst() method, here it is...

Str = Str.replaceFirst("^.*?(\\w+)$", "$1");

Henry

[Raja Mirrah]

Thanks Henry,

Even i have written the same regex which you have posted. thanks!!!