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
参考: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#rewind-
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注:本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 ByteBuffer rewind() methods in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。