Java IntBuffer rewind()方法及示例

java.nio.IntBuffer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 final IntBuffer rewind()

参数： 该方法不接受任何参数。

返回值： 该方法返回这个缓冲区。

下面是一些例子来说明rewind()方法。

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 IntBuffer
        // using allocate() method
        IntBuffer intBuffer
            = IntBuffer.allocate(4);
  
        // put char value in intBuffer
        // using put() method
        intBuffer.put(10);
        intBuffer.put(20);
  
        // print the int buffer
        System.out.println(
            "Buffer before operation: "
            + Arrays.toString(
                  intBuffer.array())
            + "\nPosition: "
            + intBuffer.position()
            + "\nLimit: "
            + intBuffer.limit());
  
        // rewind the Buffer
        // using rewind() method
        intBuffer.rewind();
  
        // print the intbuffer
        System.out.println(
            "\nBuffer after operation: "
            + Arrays.toString(
                  intBuffer.array())
            + "\nPosition: "
            + intBuffer.position()
            + "\nLimit: "
            + intBuffer.limit());
    }
}

输出:

Buffer before operation: [10, 20, 0, 0]
Position: 2
Limit: 4

Buffer after operation: [10, 20, 0, 0]
Position: 0
Limit: 4

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 IntBuffer
        // using allocate() method
        IntBuffer intBuffer
            = IntBuffer.allocate(5);
  
        // put int value in IntBuffer
        // using put() method
        intBuffer.put(10);
        intBuffer.put(20);
        intBuffer.put(30);
  
        // mark will be going to
        // discarded by rewind()
        intBuffer.mark();
  
        // print the buffer
        System.out.println(
            "Buffer before operation: "
            + Arrays.toString(
                  intBuffer.array())
            + "\nPosition: "
            + intBuffer.position()
            + "\nLimit: "
            + intBuffer.limit());
  
        // Rewind the Buffer
        // using rewind() method
        intBuffer.rewind();
  
        // print the buffer
        System.out.println(
            "\nBuffer after operation: "
            + Arrays.toString(
                  intBuffer.array())
            + "\nPosition: "
            + intBuffer.position()
            + "\nLimit: "
            + intBuffer.limit());
    }
}

输出:

Buffer before operation: [10, 20, 30, 0, 0]
Position: 3
Limit: 5

Buffer after operation: [10, 20, 30, 0, 0]
Position: 0
Limit: 5

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