java.nio.ByteBuffer类的rewind()方法用于倒带此缓冲区。位置设置为零，标记被丢弃。假设已正确设置了限制，请在序列channel-write或get操作之前调用此方法。调用此方法既不会更改，也不会丢弃标记的值。

用法:

public ByteBuffer rewind()

返回值：此方法返回此缓冲区。

下面是说明rewind()方法的示例：

范例1：

// Java program to demonstrate

// rewind() method

import java.nio.*;

import java.util.*;

public class GFG {

public static void main(String[] args)

{

// defining and allocating ByteBuffer

// using allocate() method

ByteBuffer byteBuffer = ByteBuffer.allocate(4);

// put byte value in byteBuffer

// using put() method

byteBuffer.put((byte)20);

byteBuffer.put((byte)'a');

// print the byte buffer

System.out.println("Buffer before operation:"

+ Arrays.toString(byteBuffer.array())

+ "\nPosition:" + byteBuffer.position()

+ "\nLimit:" + byteBuffer.limit());

// rewind the Buffer

// using rewind() method

byteBuffer.rewind();

// print the bytebuffer

System.out.println("\nBuffer after operation:"

+ Arrays.toString(byteBuffer.array())

+ "\nPosition:" + byteBuffer.position()

+ "\nLimit:" + byteBuffer.limit());

}

}

输出：

Buffer before operation:[20, 97, 0, 0]

Position:2

Limit:4

Buffer after operation:[20, 97, 0, 0]

Position:0

Limit:4

范例2：

// Java program to demonstrate

// rewind() method

import java.nio.*;

import java.util.*;

public class GFG {

public static void main(String[] args)

{

// defining and allocating ByteBuffer

// using allocate() method

ByteBuffer byteBuffer = ByteBuffer.allocate(5);

// put byte value in byteBuffer

// using put() method

byteBuffer.put((byte)20);

byteBuffer.put((byte)30);

byteBuffer.put((byte)40);

// mark will be going to discarded by rewind()

byteBuffer.mark();

// print the buffer

System.out.println("Buffer before operation:"

+ Arrays.toString(byteBuffer.array())

+ "\nPosition:" + byteBuffer.position()

+ "\nLimit:" + byteBuffer.limit());

// Rewind the Buffer

// using rewind() method

byteBuffer.rewind();

// print the buffer

System.out.println("\nBuffer after operation:"

+ Arrays.toString(byteBuffer.array())

+ "\nPosition:" + byteBuffer.position()

+ "\nLimit:" + byteBuffer.limit());

}

}

输出：

Buffer before operation:[20, 30, 40, 0, 0]

Position:3

Limit:5

Buffer after operation:[20, 30, 40, 0, 0]

Position:0

Limit:5