Java BreakIterator previous()方法及示例

java.text.BreakIterator 类的 previous() 方法是用来获取当前边界（通过调用current()方法获取的边界）后面的前一个边界的索引。它提供了BreakIterator指向的当前边界之前的边界的第一个字符的偏移。

语法

public abstract int previous()

参数： 该方法不接受任何参数。

返回值： 该方法提供了当前边界之后的前一个边界的 索引 。

下面是说明 previous() 方法的例子。

例1 :

// Java program to demonstrate previous() 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 index 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 previous() : "
            + current);
  
        // calling previous() method
        next = wb.previous();
  
        // display the result
        System.out.println(
            "\ncurrent position after"
            + " calling 1st previous() : "
            + next);
  
        // calling previous() method
        next = wb.previous();
  
        // display the result
        System.out.println(
            "\ncurrent position after"
            + " calling 2nd previous() : "
            + next);
    }
}

输出:

current position before calling previous() : 11

current position after calling 1st previous() : 6

current position after calling 2nd previous() : 4

例2 :

// Java program to demonstrate
// previous() 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("GeeksForGeeks");
  
        // setting the current position to index 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 previous() : "
            + current);
  
        // calling previous() method
        next = wb.previous();
  
        // display the result
        System.out.println(
            "\ncurrent position after"
            + " calling 1st previous() : "
            + next);
  
        // calling previous() method
        next = wb.previous();
  
        // display the result
        System.out.println(
            "\ncurrent position after"
            + " calling 2nd previous() : "
            + next);
    }
}

输出:

current position before calling previous() : 13

current position after calling 1st previous() : 0

current position after calling 2nd previous() : -1

参考资料: https://docs.oracle.com/javase/9/docs/api/java/text/BreakIterator.html#previous-