Java 中的 BufferedReader reset()方法，示例

原文:https://www . geeksforgeeks . org/bufferedeeler-reset-method-in-Java-with-examples/

Java 中buffere reader类的 reset() 方法是将位置固定或标记在最后标记的位置，这样就可以再次读取同一个字节。

语法:

public void reset() 
            throws IOException

覆盖:覆盖阅读器类的重置()方法。

参数:该方法不接受任何参数。

返回值:该方法不返回值。

异常:如果从未在流上调用 mark()方法，或者如果 mark 的值无效，该方法将抛出 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”的存在。

// 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());
    }
}

Output:

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

程序 2: 假设文件“c:/demo.txt”的存在。

// 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());
    }
}

Output:

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

参考文献: https://docs . Oracle . com/javase/10/docs/API/Java/io/bufferedreader . html # reset()

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