Java String split()

The java string split() method splits this string against given regular expression and returns a char array.

Internal implementation

public String[] split(String regex, int limit) {  
        /* fastpath if the regex is a 
         (1)one-char String and this character is not one of the 
            RegEx's meta characters ".$|()[{^?*+\\", or 
         (2)two-char String and the first char is the backslash and 
            the second is not the ascii digit or ascii letter. 
         */  
        char ch = 0;  
        if (((regex.value.length == 1 &&  
             ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||  
             (regex.length() == 2 &&  
              regex.charAt(0) == '\\' &&  
              (((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&  
              ((ch-'a')|('z'-ch)) < 0 &&  
              ((ch-'A')|('Z'-ch)) < 0)) &&  
            (ch < Character.MIN_HIGH_SURROGATE || ch > Character.MAX_LOW_SURROGATE))  
        {  
            int off = 0;  
            int next = 0;  
            boolean limited = limit > 0;  
            ArrayList list = new ArrayList<>();  
            while ((next = indexOf(ch, off)) != -1) {  
                if (!limited || list.size() < limit - 1) {  
                    list.add(substring(off, next));  
                    off = next + 1;  
                } else {    // last one  
                    //assert (list.size() == limit - 1);  
                    list.add(substring(off, value.length));  
                    off = value.length;  
                    break;  
                }  
            }  
            // If no match was found, return this  
            if (off == 0)  
                return new String[]{this};  
  
            // Add remaining segment  
            if (!limited || list.size() < limit) list.add(substring(off, value.length)); // Construct result int resultSize = list.size(); if (limit == 0) while (resultSize > 0 && list.get(resultSize - 1).length() == 0)  
                    resultSize--;  
            String[] result = new String[resultSize];  
            return list.subList(0, resultSize).toArray(result);  
        }  
        return Pattern.compile(regex).split(this, limit);  
    }

Signature

There are two signature for split() method in java string.

public String split(String regex)  
and,  
public String split(String regex, int limit)

Parameter

regex : regular expression to be applied on string.

limit : limit for the number of strings in array. If it is zero, it will returns all the strings matching regex.

Returns

array of strings

Throws

PatternSyntaxException if pattern for regular expression is invalid

Since

1.4

Java String split() method example

The given example returns total number of words in a string excluding space only. It also includes special characters.

public class SplitExample{  
public static void main(String args[]){  
String s1="java string split method by javatpoint";  
String[] words=s1.split("\\s");//splits the string based on whitespace  
//using java foreach loop to print elements of string array  
for(String w:words){  
System.out.println(w);  
}  
}}

java
string
split
method
by
javatpoint

Java String split() method with regex and length example

public class SplitExample2{  
public static void main(String args[]){  
String s1="welcome to split world";  
System.out.println("returning words:");  
for(String w:s1.split("\\s",0)){  
System.out.println(w);  
}  
System.out.println("returning words:");  
for(String w:s1.split("\\s",1)){  
System.out.println(w);  
}  
System.out.println("returning words:");  
for(String w:s1.split("\\s",2)){  
System.out.println(w);  
}  
  
}}

returning words:
welcome 
to 
split 
world
returning words:
welcome to split world
returning words:
welcome 
to split world

Java String split() method with regex and length example 2

Here, we are passing split limit as a second argument to this function. This limits the number of splitted strings.

public class SplitExample3 {  
    public static void main(String[] args) {  
        String str = "Javatpointtt";  
        System.out.println("Returning words:");  
        String[] arr = str.split("t", 0);  
        for (String w : arr) {  
            System.out.println(w);  
        }  
        System.out.println("Split array length: "+arr.length);  
    }  
}

Returning words:
Java
poin
Split array length: 2