Java Buffer position()用法及代碼示例

java.nio.Buffer類的position(int newPosition)方法用於設置此緩衝區的位置。如果標記已定義且大於新位置，則將其丟棄。

用法:

public Buffer position(int newPosition)

參數：此方法將newPosition作為新位置值的參數。它必須為非負且不大於電流限製。

返回值：此方法返回此緩衝區。

下麵是說明position()方法的示例：

範例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()); 
    } 
}

輸出：

position before reset:4
position after reset:2

範例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()); 
    } 
}

輸出：

position before clear:3
position after clear:0

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

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注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 Buffer position() methods in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。