Java StringBuilder offsetByCodePoints()方法及示例

StringBuilder类 的 offsetByCodePoints() 方法返回StringBuilder包含的索引，该索引与作为参数传递的codePointOffset代码点相抵。位于索引和codePointOffset之间的未配对的代用品各算作一个码点。

语法

public int offsetByCodePoints(int index,                       int codePointOffset)

参数： 该方法需要两个参数。

返回值 ：该方法返回 该序列中的索引。

异常： 如果以下任何一项为真，该方法会抛出 IndexOutOfBoundsException 。

下面的程序演示了StringBuilder类的 offsetByCodePoints()方法。

例1 :

// Java program to demonstrate// the offsetByCodePoints() Method.  class GFG {    public static void main(String[] args)    {          // create a StringBuilder object        // with a String pass as parameter        StringBuilder            str            = new StringBuilder("WelcomeGeeks");          // print string        System.out.println("String = "                           + str.toString());          // returns the index within this sequence        int returnvalue = str.offsetByCodePoints(1, 4);          // prints the index        System.out.println("Index = " + returnvalue);    }}

输出:

String = WelcomeGeeksIndex = 5

例2 :

// Java program to demonstrate// the offsetByCodePoints() Method.  class GFG {    public static void main(String[] args)    {          // create a StringBuilder object        // with a String pass as parameter        StringBuilder            str            = new StringBuilder("India Is great");          // print string        System.out.println("String = " + str.toString());          // returns the index within this sequence        int returnvalue = str.offsetByCodePoints(2, 9);          // prints the index        System.out.println("Index = " + returnvalue);    }}

输出:

String = India Is greatIndex = 11

例3：演示IndexOutOfBoundException

// Java program to demonstrate// Exception thrown by offsetByCodePoints() Method.  class GFG {    public static void main(String[] args)    {          // create a StringBuilder object        // with a String pass as parameter        StringBuilder            str            = new StringBuilder("India");          try {              // returns the index within this sequence            int returnvalue = str.offsetByCodePoints(2, 9);              // prints the index            System.out.println("Index = " + returnvalue);        }          catch (IndexOutOfBoundsException e) {            System.out.println("Exception: " + e);        }    }}

输出:

Exception: java.lang.IndexOutOfBoundsException

参考资料：
https://docs.oracle.com/javase/10/docs/api/java/lang/StringBuilder.html#offsetByCodePoints(int, int)。