Java StringBuilder offsetByCodePoints()

The offsetByCodePoints(int index, int codePointOffset) method returns the index of a character that is offset from the given index by the specified code points.

Syntax of offsetByCodePoints() Method:

int index = sb.offsetByCodePoints(3, 4);

The above statement will return the index of a character that is 4 code points away from the character present at index 3.

offsetByCodePoints() Description

public int offsetByCodePoints(int index, int codePointOffset): Returns the index of a character that is specified code points away from the character present at the given index.

offsetByCodePoints() Parameters

It takes two parameters:

• index: Gives the starting position. Integer index value that specifies a char in sequence. The offset count starts from here.
• codePointOffset: It is the integer offset value in code points.

offsetByCodePoints() Return Value

• Returns an index of character in the sequence represented by objected of StringBuilder class.

It throws IndexOutOfBoundsException, if any of the following condition occurs:

• If index < 0 or > sb.length()
• If codePointOffset is positive and index + codePointOffset > sb.length()
• If codePointOffset is negative and index + codePointOffset < 0

Also Read: StringBuilder in Java

Example 1: Finding index of an offset character

public class JavaExample {
  public static void main(String[] args) {
    StringBuilder sb = new StringBuilder("Welcome");
    //starting index 0, offset 2
    int index = sb.offsetByCodePoints(0,2);
    //Index of char that is 2 code points away from first char
    System.out.println("Index of offset char: "+index);
  }
}

Output:

Example 2: If codePointOffset is negative

public class JavaExample {
  public static void main(String[] args) {
    StringBuilder sb = new StringBuilder("Welcome");
    //starting index 5, offset -2
    int index = sb.offsetByCodePoints(5,-2);
    System.out.println("Index of offset char: "+index);
  }
}

Output:

Example 3: If index + codePointOffset is greater than the length of Sequence

public class JavaExample {
  public static void main(String[] args) {
    StringBuilder sb = new StringBuilder("Welcome");
    //starting index 5, offset 5
    int index = sb.offsetByCodePoints(5,5);
    System.out.println("Index of offset char: "+index);
  }
}

Output:

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