BufferedReader类mark()方法 (BufferedReader Class mark() method)

• mark() method is available in java.io package.

  mark()方法在java.io包中可用。

• mark() method is used to mark the current position in this stream and whenever we call reset() method so it will reset the stream to the given point (read_from_here).

  mark()方法用于标记此流中的当前位置，并且每当我们调用reset()方法时，都会将流重置到给定点(read_from_here)。

• mark() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  mark()方法是一种非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• mark() method may throw an exception at the time of setting a limit.

  设置限制时， mark()方法可能会引发异常。

  • IllegalArgumentException: This exception may throw when the given parameter is negative.IllegalArgumentException ：如果给定参数为负，则可能引发此异常。
  • IOException: This exception may throw while performing input/output operation.IOException ：在执行输入/输出操作时，可能会抛出此异常。

Syntax:

句法：

    public void mark(int read_from_here);

Parameter(s):

参数：

• int read_from_here – represents the number of bytes to read during mark() preserves.

  int read_from_here –表示mark()保留期间要读取的字节数。

Return value:

返回值：

The return type of the method is void, it returns nothing.

该方法的返回类型为void ，不返回任何内容。

Example:

例：

// Java program to demonstrate the example 
// of void mark(int read_from_here) method of 
// BufferedReader
import java.io.*;
public class MarkBR {
public static void main(String[] args) throws Exception {
// To open text file by using 
// FileInputStream
FileInputStream fis = new FileInputStream("e:/includehelp.txt");
// Instantiates InputStreamReader 
InputStreamReader inp_r = new InputStreamReader(fis);
// Instantiates BufferedReader 
BufferedReader buff_r = new BufferedReader(inp_r);
// Read character from the stream
char ch1 = (char) buff_r.read();
char ch2 = (char) buff_r.read();
char ch3 = (char) buff_r.read();
System.out.println("ch1: " + ch1);
System.out.println("ch2 : " + ch2);
// By using mark() method isto
// set the limit the number of byte
// to be read 
System.out.println("buff_r.mark(5): ");
buff_r.mark(5);
System.out.println("ch3: " + ch3);
// reset stream by using reset()
System.out.println("buff_r.reset(): ");
buff_r.reset();
// Read from the stread
char ch4 = (char) buff_r.read();
char ch5 = (char) buff_r.read();
// Display character
System.out.println("ch4: " + ch4);
System.out.println("ch5: " + ch5);
fis.close();
inp_r.close();
buff_r.close();
}
}

Output

输出量

ch1: H
ch2 : e
buff_r.mark(5):
ch3: l
buff_r.reset():
ch4: l
ch5: o

翻译自: https://www.includehelp.com/java/bufferedreader-mark-method-with-example.aspx