TRIM, LTRIM and RTRIM in Java

In java, we have trim() method to remove trailing and leading spaces.

String s = "         dsafsdafdsa dfasfda asfdasf asdfsaf       ";
System.out.println(s.trim());


But there are no direct methods for L-TRIM or R-TRIM individually.

Below are the some of the implementations of L-TRIM and R-TRIM:

Method1:
Implementing using Regular Expressions

String ltrim = s.replaceAll("^\\s+","");
String rtrim = s.replaceAll("\\s+$","");

very simple right..... :)

Method2:
If you have to do it often, you can create and compile a pattern for better performance

private final static Pattern LTRIM = Pattern.compile("^\\s+");
private final static Pattern RTRIM = Pattern.compile("\\s+$");

public static String ltrim(String s) {
    return LTRIM.matcher(s).replaceAll("");
}

public static String rtrim(String s) {
    return RTRIM.matcher(s).replaceAll("");
}


Method3:
Implemented by removing the white spaces.
This method is least prefered.

public static String ltrim3(String s) {
    int i = 0;
    while (i < s.length() && Character.isWhitespace(s.charAt(i))){
        i++;
    }
    return s.substring(i);
}

public static String rtrim3(String s) {
    int i = s.length()-1;
    while (i >= 0 && Character.isWhitespace(s.charAt(i))) {
        i--;
    }
    return s.substring(0,i+1);
}