Java中的 BufferedReader reset() 方法及示例

Java中BufferedReader类的reset()方法用于固定或标记上一次标记位置的位置，以便再次读取相同的字节。

句法：

public void reset() 
            throws IOException

覆盖：它覆盖了Reader类的 reset() 方法。

参数：该方法不接受任何参数。

返回值：该方法不返回任何值。

异常：如果 mark() 方法从未在流上调用或者如果 mark 的值无效，则该方法将引发IOException 。

下面的程序说明了 IO 包中 BufferedReader 类中的 reset() 方法：

程序1：假设文件“c:/demo.txt”存在。

// Java program to illustrate
// BufferedReader reset() method
  
import java.io.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Read the stream 'demo.txt'
        // for containing text "GEEKS"
        FileReader fileReader
            = new FileReader(
                "c:/demo.txt");
  
        // Convert fileReader to
        // bufferedReader
        BufferedReader buffReader
            = new BufferedReader(
                fileReader);
  
        // Read and print characters
        // one by one
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
  
        // Mark is set on the stream
        buffReader.mark(0);
  
        System.out.println(
            "Char : "
            + (char)buffReader.read());
  
        // Reset() is invoked
        buffReader.reset();
  
        // Read and print characters
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
    }
}

输出：

Char : G
Char : E
Char : E
Char : K
Char : K
Char : S

程序2：假设文件“c:/demo.txt”存在。

// Java program to illustrate
// BufferedReader reset() method
import java.io.*;
public class GFG {
    public static void main(String[] args)
    {
  
        // Read the stream 'demo.txt'
        // containing text "GEEKSFORGEEKS"
        FileReader fileReader
            = new FileReader(
                "c:/demo.txt");
  
        // Convert fileReader to
        // bufferedReader
        BufferedReader buffReader
            = new BufferedReader(
                fileReader);
  
        // Read and print characters
        // one by one
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
  
        // Mark is set on the stream
        buffReader.mark(0);
  
        System.out.println(
            "Char : "
            + (char)buffReader.read());
  
        // Reset() is invoked
        buffReader.reset();
  
        // read and print characters
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
        System.out.println(
            "Char : "
            + (char)buffReader.read());
    }
}

输出：

Char : G
Char : E
Char : E
Char : K
Char : S
Char : S
Char : F
Char : O
Char : R

参考：
https://docs.oracle.com/javase/10/docs/api/java Java()