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Java LineNumberReader reset()用法及代码示例


LineNumberReader类reset()方法

  • reset() 方法可在java.io包。
  • reset() 方法用于将此 LineNumberReader 流重置为通过调用其 mark() 方法设置的最新标记的位置。
  • reset() 方法是一个非静态方法,它只能通过类对象访问,如果我们尝试使用类名访问方法,那么我们将得到一个错误。
  • reset() 方法可能会在重置流时抛出异常。
    IOException:当此流尚未标记或设置标记无效时,可能会抛出此异常。

用法:

    public void reset();

参数:

  • 它不接受任何参数。

返回值:

该方法的返回类型是void,它什么都不返回。

例:

// Java program to demonstrate the example 
// of void reset() method of LineNumberReader

import java.io.*;

public class ResetOfLNR {
 public static void main(String[] args) throws Exception {
  FileReader fr_stm = null;
  LineNumberReader line_r = null;
  int val = 0;

  try {
   // Instantiates FileReader and LineNumberReader
   fr_stm = new FileReader("D:\\includehelp.txt");
   line_r = new LineNumberReader(fr_stm);

   // By using read() method isto 
   // read the character from line_r
   char ch1 = (char) line_r.read();
   char ch2 = (char) line_r.read();
   char ch3 = (char) line_r.read();

   System.out.println("ch1:" + ch1);
   System.out.println("ch2:" + ch2);
   System.out.println("ch3:" + ch3);

   // By using mark() method isto
   // set the current position in this
   // line_r

   System.out.println("line_r.mark(0):");
   line_r.mark(0);
   char ch4 = (char) line_r.read();
   char ch5 = (char) line_r.read();

   System.out.println("ch4:" + ch4);
   System.out.println("ch5:" + ch5);

   // By using reset() method isto
   // reset the stream to the position 
   // set by the call mark() method

   System.out.println("line_r.reset():");
   line_r.reset();
   char ch6 = (char) line_r.read();
   char ch7 = (char) line_r.read();
   char ch8 = (char) line_r.read();
   char ch9 = (char) line_r.read();
   char ch10 = (char) line_r.read();
   char ch11 = (char) line_r.read();


   System.out.println("ch4:" + ch6);
   System.out.println("ch5:" + ch7);
   System.out.println("ch6:" + ch8);
   System.out.println("ch7:" + ch9);
   System.out.println("ch8:" + ch10);
   System.out.println("ch9:" + ch11);

  } catch (Exception ex) {
   System.out.println(ex.toString());
  } finally {
   // with the help of this block is to
   // free all necessary resources linked
   // with the stream
   if (fr_stm != null) {
    fr_stm.close();
    if (line_r != null) {
     line_r.close();
    }
   }
  }
 }
}

输出

ch1:J
ch2:A
ch3:V
line_r.mark(0):
ch4:A
ch5:W
line_r.reset():
ch4:A
ch5:W
ch6:O
ch7:R
ch8:L
ch9:D


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注:本文由纯净天空筛选整理自Preeti Jain大神的英文原创作品 Java LineNumberReader reset() Method with Example。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。