Java Character codePointBefore()方法

java.lang.Character.codePointBefore(CharSequence seq, int index) 返回CharSequence的给定索引前面的代码点。如果在(index - 1)的char值在CharSequence是在低代理项范围，(index - 2)不为负，char值(index - 2)在CharSequence的是在高代理项范围，则对应于此代理项对的增补代码点返回。否则，在(index - 1)处的char值返回。

1 语法

public static int codePointBefore(CharSequence seq, int index)

2 参数

seq：该实例的CharSequence

index：下面返回代码点的索引

3 返回值

此方法将返回给定索引之前的Unicode代码点值。

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java Character codePointBefore()方法
 */
import java.lang.*;

public class CharacterDemo {

   public static void main(String[] args) {

      // create a CharSequence seq and assign value
      CharSequence seq = "Hello";

      // create and assign value to index
      int index  = 4;

      // create an int res
      int res;

      // assign result of codePointBefore on seq at index to res
      res = Character.codePointBefore(seq, index);

      String str = "Unicode code point is " + res;

      // print res value
      System.out.println( str );
   }
}

输出结果为：

Unicode code point is 108