Java PushbackReader unread()方法

java.io.PushbackReader.unread(int c) 方法将其复制到推回缓冲区前面推回一个字符。此方法返回后，将下一个字符被读取的值(字符)。

1 语法

public void unread(int c)

2 参数

c：整型值，表示一个字符被推回

3 返回值

无

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * java.io.PushbackReader.unread(int c)方法的例子
 */
import java.io.*;

public class Demo {
    public static void main(String[] args) {
        String s = "Hello World";

        // create a new StringReader
        StringReader sr = new StringReader(s);

        // create a new PushBack reader based on our string reader
        PushbackReader pr = new PushbackReader(sr, 20);

        try {
            // read the first five chars
            for (int i = 0; i < 5; i++) {
                char c = (char) pr.read();
                System.out.print("" + c);
            }

            // change line
            System.out.println();

            // unread a character
            pr.unread('F');

            // read the next char, which is the one we unread
            char c = (char) pr.read();

            // print that character
            System.out.println("" + c);

            // close the stream
            pr.close();

        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}

输出结果为：

Hello
F