Java 中的 Reader reset()方法，示例

原文:https://www . geesforgeks . org/reader-reset-method-in-Java-with-examples/

Java 中 Reader 类的 reset() 方法用于重置流。重置后，如果流已被标记，则此方法尝试在标记处重新定位它，否则它将尝试将其定位到起点。

语法:

public void reset()

参数:该方法不接受任何参数。

返回值:此方法不返回值。

异常:如果输入输出时出现错误

  • If the stream is not marked If the tag is invalid If the reset () method is not supported, this method throws IOException:
    • 。

下面的方法说明了 reset()方法的工作原理:

程序 1:

// Java program to demonstrate
// Reader reset() method

import java.io.*;
import java.util.*;

class GFG {
    public static void main(String[] args)
    {

        try {

            String str = "GeeksForGeeks";

            // Create a Reader instance
            Reader reader
                = new StringReader(str);

            // Get the character
            // to be read from the stream
            int ch;

            // Read the first 10 characters
            // to this reader using read() method
            // This will put the str in the stream
            // till it is read by the reader
            for (int i = 0; i < 10; i++) {
                ch = reader.read();
                System.out.print((char)ch);
            }

            System.out.println();

            // mark the stream for
            // 5 characters using reset()
            reader.mark(5);

            // reset the stream position
            reader.reset();

            // Read the 5 characters from marked position
            // to this reader using read() method
            for (int i = 0; i < 5; i++) {
                ch = reader.read();
                System.out.print((char)ch);
            }
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出:

GeeksForGe
eks??

程序二:

// Java program to demonstrate
// Reader reset() method

import java.io.*;
import java.util.*;

class GFG {
    public static void main(String[] args)
    {

        try {
            String str = "GeeksForGeeks";

            // Create a Reader instance
            Reader reader
                = new StringReader(str);

            // Get the character
            // to be read from the stream
            int ch;

            // Read the first 10 characters
            // to this reader using read() method
            // This will put the str in the stream
            // till it is read by the reader
            for (int i = 0; i < 10; i++) {
                ch = reader.read();
                System.out.print((char)ch);
            }

            System.out.println();

            // reset the stream position
            reader.reset();

            // Read the 5 characters from marked position
            // to this reader using read() method
            for (int i = 0; i < 5; i++) {
                ch = reader.read();
                System.out.print((char)ch);
            }
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出:

GeeksForGe
Geeks

参考:https://docs . Oracle . com/javase/9/docs/API/Java/io/reader . html # reset–

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