Java中的BreakIteratorprevious()方法和示例

Java .text.BreakIterator类的preceding()方法用于获取指定字符偏移边界之前最后一个边界字符的索引。它提供了在 BreakIterator 指向的当前边界之后或之前的边界第一个字符的偏移量。

句法：

public int preceding(int offset)

参数：它需要找到前一个边界的字符的偏移量。

返回值：此方法提供指定字符偏移之前的边界索引。

异常：如果指定的索引小于第一个文本边界或大于最后一个文本边界，则此方法抛出IllegalArgumentException 。

以下是说明previous()方法的示例：

示例 1：

// Java program to demonstrate preceding() method
  
import java.text.*;
import java.util.*;
import java.io.*;
  
public class GFG {
    public static void main(String[] argv)
    {
        // creating and initializing with zero
        int current = 0, next = 0;
  
        // creating and initializing BreakIterator
        BreakIterator wb
            = BreakIterator.getWordInstance();
  
        // setting text for BreakIterator
        wb.setText("Code  Geeks");
  
        // setting the current position to 11
        // by skipping 3 boundaries
        wb.next(3);
  
        // getting the current text boundary
        current = wb.current();
  
        // display the result
        System.out.println(
            "current position before"
            + " calling preceding() : "
            + current);
  
        // calling preceding() method
        next = wb.preceding(6);
  
        // display the result
        System.out.println(
            "\ncurrent position after"
            + " calling 1st preceding() : "
            + next);
  
        // calling preceding() method
        next = wb.preceding(11);
  
        // display the result
        System.out.println(
            "\ncurrent position after"
            + " calling 2nd preceding() : "
            + next);
    }
}

输出：

current position before calling preceding() : 11

current position after calling 1st preceding() : 4

current position after calling 2nd preceding() : 6

示例 2：

// Java program to demonstrate preceding() method
  
import java.text.*;
import java.util.*;
import java.io.*;
  
public class GFG {
    public static void main(String[] argv)
    {
        try {
            // creating and initializing with zero
            int current = 0, next = 0;
  
            // creating and initializing BreakIterator
            BreakIterator wb
                = BreakIterator.getWordInstance();
  
            // setting text for BreakIterator
            wb.setText("Code  Geeks");
  
            // setting the current position to 11
            // by skipping 3 boundaries
            wb.next(3);
  
            // getting the current text boundary
            current = wb.current();
  
            // display the result
            System.out.println(
                "current position before"
                + " calling preceding() : "
                + current);
  
            // calling preceding() method
            next = wb.preceding(6);
  
            // display the result
            System.out.println(
                "\ncurrent position after"
                + " calling 1st preceding() : "
                + next);
  
            // calling preceding() method
            next = wb.preceding(-1);
  
            // display the result
            System.out.println(
                "\ncurrent position after"
                + " calling 2nd preceding() : "
                + next);
        }
        catch (IllegalArgumentException e) {
  
            System.out.println(
                "\noffset is less than the first boundary");
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出：

current position before calling preceding() : 11

current position after calling 1st preceding() : 4

offset is less than the first boundary
Exception thrown : java.lang.IllegalArgumentException: offset out of bounds

参考： https://docs.oracle.com/javase/9/docs/api/ Java/text/BreakIterator.html#preceding-int-