极客教程Java CharBuffer rewind()方法及示例
java.nio.CharBuffer类的 rewind() 方法是用来倒退这个缓冲区的。位置被设置为零，标记被丢弃。在一连串的channel-write或get操作之前调用这个方法，假设限制已经被适当地设置了。调用这个方法既不改变也不丢弃标记的值。
语法
public ByteBuffer rewind()Java
返回值： 该方法返回这个缓冲区。
下面是说明rewind()方法的例子。
例子 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 CharBuffer
// using allocate() method
CharBuffer charBuffer = CharBuffer.allocate(4);
// put char value in charBuffer
// using put() method
charBuffer.put('a');
charBuffer.put((char)105);
// print the char buffer
System.out.println("Buffer before operation: "
+ Arrays.toString(
charBuffer.array())
+ "\nPosition: "
+ charBuffer.position()
+ "\nLimit: "
+ charBuffer.limit());
// rewind the Buffer
// using rewind() method
charBuffer.rewind();
// print the charbuffer
System.out.println("\nBuffer after operation: "
+ Arrays.toString(
charBuffer.array())
+ "\nPosition: "
+ charBuffer.position()
+ "\nLimit: "
+ charBuffer.limit());
}
}Java
输出:
Buffer before operation: [a, i,, ]
Position: 2
Limit: 4
Buffer after operation: [a, i,, ]
Position: 0
Limit: 4Java
例子 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 CharBuffer
// using allocate() method
CharBuffer charBuffer
= CharBuffer.allocate(5);
// put byte value in charBuffer
// using put() method
charBuffer.put('a');
charBuffer.put('b');
charBuffer.put('c');
// mark will be going to discarded by rewind()
charBuffer.mark();
// print the buffer
System.out.println("Buffer before operation: "
+ Arrays.toString(
charBuffer.array())
+ "\nPosition: "
+ charBuffer.position()
+ "\nLimit: "
+ charBuffer.limit());
// Rewind the Buffer
// using rewind() method
charBuffer.rewind();
// print the buffer
System.out.println("\nBuffer after operation: "
+ Arrays.toString(
charBuffer.array())
+ "\nPosition: "
+ charBuffer.position()
+ "\nLimit: "
+ charBuffer.limit());
}
}Java
输出:
Buffer before operation: [a, b, c,, ]
Position: 3
Limit: 5
Buffer after operation: [a, b, c,, ]
Position: 0
Limit: 5Java
参考资料: https://docs.oracle.com/javase/9/docs/api/java/nio/CharBuffer.html#rewind-