Java Buffer reset()方法及示例

java.nio.Buffer类的 reset() 方法是用来将这个缓冲区的位置重置到之前标记的位置。调用这个方法既不改变也不丢弃标记的值。

语法：

public Buffer reset()

返回值： 该方法返回这个缓冲区。

以下是说明reset()方法的例子：

例子1：

// Java program to demonstrate// reset() method import java.nio.*;import java.util.*; public class GFG {     public static void main(String[] args)    {        try {             byte[] barr = { 10, 20, 30, 40 };             // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.wrap(barr);             // Typecast ByteBuffer to buffer            Buffer buffer = (Buffer)bb;             // try to set the position at index 2            buffer.position(2);             // Set this buffer mark position            // using mark() method            buffer.mark();             // try to set the position at index 4            buffer.position(4);             // display position            System.out.println("position before reset: "                               + buffer.position());             // try to call reset() to restore            // to the position we marked            buffer.reset();             // display position            System.out.println("position after reset: "                               + buffer.position());        }         catch (InvalidMarkException e) {            System.out.println("new position is less than "                               + "the position we marked before ");            System.out.println("Exception throws: " + e);        }    }}

输出

position before reset: 4position after reset: 2

实例2：

// Java program to demonstrate// reset() method import java.nio.*;import java.util.*; public class GFG {     public static void main(String[] args)    {         try {             byte[] barr = { 10, 20, 30, 40 };             // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.wrap(barr);             // Typecast ByteBuffer to buffer            Buffer buffer = (Buffer)bb;             // try to set the position at index 2            buffer.position(2);             // Set this buffer mark position            // using mark() method            buffer.mark();             // try to set the position at index 4            buffer.position(1);             // display position            System.out.println("position before reset: "                               + buffer.position());             // try to call reset() to restore            // to the position we marked            buffer.reset();             // display position            System.out.println("position after reset: "                               + buffer.position());        }         catch (InvalidMarkException e) {            System.out.println("\new position is less than "                               + "the position we marked before ");            System.out.println("Exception throws: " + e);        }    }}

输出

position before reset: 1new position is less than the position we marked before Exception throws: java.nio.InvalidMarkException

参考资料: https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.html#reset-