Java String substring() method example

The Java String substring() method returns a new string that is a substring of this string. substring() method is overloaded method and comes in two variants:

1. String substring(int beginIndex)
2. String substring​(int beginIndex, int endIndex)

Where method arguments are:

• beginIndex – the beginning index, inclusive.
• endIndex – the ending index, exclusive.

1. Java String substring(int beginIndex) example

It returns a string that is a substring of the string. The substring begins with the character at the specified 'beginIndex' to the end of string.

1. Please note that index starts from ‘0’ which refer to first character of String.
2. Method will throw StringIndexOutOfBoundsException error if argument index is not a valid index. A valid index is always greater than or equal to zero; or less than or equal to the length of string.

0 >= Valid index <= length of string

Java program to get substring of a string from given index.

public class StringExample 
{
    public static void main(String[] args) 
    {
        String blogName = "howtodoinjava.com";

        System.out.println(blogName.substring(3));	//todoinjava.com
        
        System.out.println("hello world".substring(6));	//world
    }
}

Program output.

todoinjava.com
world

2. Java String substring(int beginIndex, int endIndex) example

It returns a string that is a substring of the string. The substring begins with the character at the specified 'beginIndex' (included) to the 'endIndex' (excluded) position.

Java program to get substring of a string from given start index to end index.

public class StringExample 
{
    public static void main(String[] args) 
    {
        String blogName = "howtodoinjava.com";

        System.out.println(blogName.substring(14, blogName.length()));	//com
        	
        System.out.println("hello world".substring(6,9));	//wor
       
        System.out.println("0123456789".substring(3, 7));	//3456
    }
}

Program output.

com
wor
3456

In last statement, example makes more sense as each character represent it’s index position in the string. ‘0’ at 0th index, ‘1’ at first index and so on till ‘9’ at ninth position.

When we find a substring from index 3 to index 7, we get string ‘3456’. Begin index is included and end index ‘7’ got excluded.

Happy Learning !!

References:

Java String Doc