Java Buffer position()用法及代码示例

java.nio.Buffer类的position(int newPosition)方法用于设置此缓冲区的位置。如果标记已定义且大于新位置，则将其丢弃。

用法:

public Buffer position(int newPosition)

参数：此方法将newPosition作为新位置值的参数。它必须为非负且不大于电流限制。

返回值：此方法返回此缓冲区。

下面是说明position()方法的示例：

范例1：

// Java program to demonstrate 
// position() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
        byte[] barr = { 10, 20, 30, 40 }; 
  
        // creating object of ByteBuffer 
        // and allocating size capacity 
        ByteBuffer bb = ByteBuffer.wrap(barr); 
  
        // Typecasting ByteBuffer into Buffer 
        Buffer bb1 = (Buffer)bb; 
  
        // try to set the position at index 2 
        // using position() method 
        bb1.position(2); 
  
        // Set this buffer mark position 
        bb1.mark(); 
  
        // try to set the position at index 4 
        // using position() method 
        bb1.position(4); 
  
        // display position 
        System.out.println("position before reset:"
                           + bb.position()); 
  
        // try to call reset() to restore 
        // to the position we marked 
        bb1.reset(); 
  
        // display position 
        System.out.println("position after reset:"
                           + bb1.position()); 
    } 
}

输出：

position before reset:4
position after reset:2

范例2：

// Java program to demonstrate 
// position() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
        // creating object of ByteBuffer 
        // and allocating size capacity 
        ByteBuffer bb = ByteBuffer.allocate(4); 
  
        // Typecasting ByteBuffer into Buffer 
        Buffer bb1 = (Buffer)bb; 
  
        // try to set the position at index 1 
        // using position() method 
        bb1.position(3); 
  
        // display position 
        System.out.println("position before clear:"
                           + bb1.position()); 
  
        // try to clear the Buffer 
        // using clear() method 
        bb1.clear(); 
  
        // display position 
        System.out.println("position after clear:"
                           + bb1.position()); 
    } 
}

输出：

position before clear:3
position after clear:0

参考： https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.html#position-int-

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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 Buffer position() 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。