Java String subSequence() method with Examples

The Java.lang.String.subSequence() is a built-in function in Java that returns a CharSequence. CharSequence that is a subsequence of this sequence. The subsequence starts with the char value at the specified index and ends with the char value at (end-1). The length (in chars) of the returned sequence is (end-start, so if start == end then an empty sequence is returned.

Syntax:

public CharSequence subSequence(int start, int end) 
Parameters: 
start - This is the index from where the subsequence starts, it is inclusive.
end - This is the index where the subsequence ends, it is exclusive.

Returns:
It returns the specified subsequence in range [start, end).

Errors and Exceptions:
IndexOutOfBoundsException – It throws this error if start or end are negative, if end is greater than length(), or if start is greater than end.

Program 1: To show working of Java.lang.String.subSequence() function.

// Java program to demonstrate working
// of Java.lang.String.subSequence() method
import java.lang.Math;

class Gfg {

    // driver code
    public static void main(String args[])
    {

        String Str = "Welcome to geeksforgeeks";

        // prints the subsequence from 0-7, exclusive 7th index
        System.out.print("Returns: ");
        System.out.println(Str.subSequence(0, 7));

        System.out.print("Returns: ");
        System.out.println(Str.subSequence(10, 24));
    }
}

Output:

Returns: Welcome
Returns:  geeksforgeeks

Program 2: To show error of Java.lang.String.subSequence() function when index is negative

// Java program to demonstrate error
// of Java.lang.String.subSequence() method
import java.lang.Math;

class Gfg {

    // driver code
    public static void main(String args[])
    {

        String Str = "Welcome to geeksforgeeks";

        // throws an error as index is negative
        System.out.print("Returns: ");
        System.out.println(Str.subSequence(-1, 7));
    }
}

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: 
String index out of range: -1
    at java.lang.String.substring(String.java:1960)
    at java.lang.String.subSequence(String.java:2003)
    at Gfg.main(File.java:15)

Program 3: To show error of Java.lang.String.subSequence() function when index is out of range.

// Java program to demonstrate error
// of Java.lang.String.subSequence() method
import java.lang.Math;

class Gfg {

    // driver code
    public static void main(String args[])
    {

        String Str = "Welcome to geeksforgeeks";

        // throws an error as end is out of range
        System.out.print("Returns: ");
        System.out.println(Str.subSequence(10, 50));
    }
}

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: 
String index out of range: 50
    at java.lang.String.substring(String.java:1963)
    at java.lang.String.subSequence(String.java:2003)
    at Gfg.main(File.java:16)