StringBuffer codePointCount() method in Java with Examples

The codePointCount() method of StringBuffer class is used to return the number of Unicode code points in the specified range of beginIndex to endIndex of String contained by StringBuffer. This method takes beginIndex and endIndex as a parameter where beginIndex is the index of the first character of the text range and endIndex is index after the last character of the text range. The indexes refer to char values (Unicode code units) and the value of index must be lie between 0 to length-1. The range starts at the beginIndex and end at the char at index endIndex – 1. Thus the length (in chars) of the text range is endIndex-beginIndex.

Syntax:

public int codePointCount(int beginIndex,
                               int endIndex)

Parameters: This method takes two parameters:

• beginIndex: int value representing index of the first character of the text range.
• endIndex: int value representing index after the last character of the text range.

Return Value: This method returns int value representing the number of Unicode code points in the specified text range.

Exception: This method throws IndexOutOfBoundsException if:

• the beginIndex is less than zero,
• or endIndex is larger than the length of String,
• or beginIndex is larger than endIndex.

Below programs illustrate the StringBuffer.codePointCount() method:

Example 1:

// Java program to demonstrate
// the codePointCount() Method.

class GFG {
    public static void main(String[] args)
    {

        // create a StringBuffer object
        // with a String pass as parameter
        StringBuffer
            str
            = new StringBuffer("Welcome to GeeksforGeeks");

        // print string
        System.out.println("String = " + str.toString());

        // returns the codepoint count from index 4 to 10
        int codepoints = str.codePointCount(4, 10);

        System.out.println("No of Unicode code points "
                           + " between index 4 and index 10 = "
                           + +codepoints);
    }
}

Output:

String = Welcome to GeeksforGeeks
No of Unicode code points  between index 4 and index 10 = 6

Example 2:

// Java program to demonstrate
// the codePointCount() Method.

class GFG {
    public static void main(String[] args)
    {

        // create a StringBuffer object
        // with a String pass as parameter
        StringBuffer
            str
            = new StringBuffer("GeeksForGeeks contribute");

        // print string
        System.out.println("String = "
                           + str.toString());

        // returns the codepoint count
        // from index 3 to 7
        int
            codepoints
            = str.codePointCount(13, 17);

        System.out.println("No of Unicode code points"
                           + " between index 13 and 17 = "
                           + codepoints);
    }
}

Output:

String = GeeksForGeeks contribute
No of Unicode code points between index 13 and 17 = 4

Example 3: To demonstrate IndexOutOfBoundsException

// Java program to demonstrate
// exception thrown by the codePointCount() Method.

class GFG {
    public static void main(String[] args)
    {

        // create a StringBuffer object
        // with a String pass as parameter
        StringBuffer
            str
            = new StringBuffer("GeeksForGeeks");

        try {

            // make beginIndex greater than endIndex
            int codepoints = str.codePointCount(2, 0);
        }

        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

Output:

Exception: java.lang.IndexOutOfBoundsException

References:
https://docs.oracle.com/javase/10/docs/api/java/lang/StringBuffer.html#codePointCount(int, int)