Java FilterReader reset()用法及代码示例

FilterReader类reset()方法

• reset() 方法可在java.io包。
• reset() 方法用于将流重置为最近调用 mark() 方法设置的位置。
• 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:当给定的参数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 FilterReader

import java.io.*;

public class ResetOfFR {
 public static void main(String[] args) throws Exception {
  Reader r_stm = null;
  FilterReader fr_stm = null;

  try {
   // Instantiates StringReader and 
   // FilterReader
   r_stm = new StringReader("JavaWorld!!!!");
   fr_stm = new FilterReader(r_stm) {};

   // By using read() method isto 
   // read the character from fr_stm
   char ch1 = (char) fr_stm.read();
   char ch2 = (char) fr_stm.read();
   char ch3 = (char) fr_stm.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
   // fr_stm
   System.out.println("fr_stm.mark(1):");
   fr_stm.mark(1);
   char ch4 = (char) fr_stm.read();
   char ch5 = (char) fr_stm.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("fr_stm.reset():");
   fr_stm.reset();
   char ch6 = (char) fr_stm.read();
   char ch7 = (char) fr_stm.read();
   char ch8 = (char) fr_stm.read();
   char ch9 = (char) fr_stm.read();
   char ch10 = (char) fr_stm.read();
   char ch11 = (char) fr_stm.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();
   }
  }
 }
}

输出

ch1:J
ch2:a
ch3:v
fr_stm.mark(1):
ch4:a
ch5:W
fr_stm.reset():
ch4:a
ch5:W
ch6:o
ch7:r
ch8:l
ch9:d