Java DoubleBuffer rewind()用法及代碼示例

java.nio.DoubleBuffer類的rewind()方法用於倒帶此緩衝區。此方法將位置設置為零，並且限製不受影響，並且如果有任何先前標記的位置將被丟棄。
當需要對channel-write進行序列化或進行get操作時，應調用此方法。這意味著，如果已經寫入了緩衝區數據，則需要將其複製到另一個數組中。例如：

 
out.write(buf);    // Writes remaining data
buf.rewind();      // Rewind the buffer
buf.get(array);    // Copy the data into array

用法:

public final DoubleBuffer rewind()

參數：該方法不帶任何參數。

返回值：此方法返回此緩衝區。

下麵是說明rewind()方法的示例：

範例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 DoubleBuffer 
        // using allocate() method 
        DoubleBuffer doubleBuffer = DoubleBuffer.allocate(4); 
  
        // put char value in doubleBuffer 
        // using put() method 
        doubleBuffer.put(10.5); 
        doubleBuffer.put(20.5); 
  
        // print the double buffer 
        System.out.println("Buffer before operation: "
                           + Arrays.toString( 
                                 doubleBuffer.array()) 
                           + "\nPosition: "
                           + doubleBuffer.position() 
                           + "\nLimit: "
                           + doubleBuffer.limit()); 
  
        // rewind the Buffer 
        // using rewind() method 
        doubleBuffer.rewind(); 
  
        // print the doublebuffer 
        System.out.println("\nBuffer after operation: "
                           + Arrays.toString( 
                                 doubleBuffer.array()) 
                           + "\nPosition: "
                           + doubleBuffer.position() 
                           + "\nLimit: "
                           + doubleBuffer.limit()); 
    } 
}

輸出：

Buffer before operation: [10.5, 20.5, 0.0, 0.0]
Position: 2
Limit: 4

Buffer after operation: [10.5, 20.5, 0.0, 0.0]
Position: 0
Limit: 4

範例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 DoubleBuffer 
        // using allocate() method 
        DoubleBuffer doubleBuffer 
            = DoubleBuffer.allocate(5); 
  
        // put double value in doubleBuffer 
        // using put() method 
        doubleBuffer.put(10.5); 
        doubleBuffer.put(20.5); 
        doubleBuffer.put(30.5); 
  
        // mark will be going to discarded by rewind() 
        doubleBuffer.mark(); 
  
        // print the buffer 
        System.out.println("Buffer before operation: "
                           + Arrays.toString( 
                                 doubleBuffer.array()) 
                           + "\nPosition: "
                           + doubleBuffer.position() 
                           + "\nLimit: "
                           + doubleBuffer.limit()); 
  
        // Rewind the Buffer 
        // using rewind() method 
        doubleBuffer.rewind(); 
  
        // print the buffer 
        System.out.println("\nBuffer after operation: "
                           + Arrays.toString( 
                                 doubleBuffer.array()) 
                           + "\nPosition: "
                           + doubleBuffer.position() 
                           + "\nLimit: "
                           + doubleBuffer.limit()); 
    } 
}

輸出：

Buffer before operation: [10.5, 20.5, 30.5, 0.0, 0.0]
Position: 3
Limit: 5

Buffer after operation: [10.5, 20.5, 30.5, 0.0, 0.0]
Position: 0
Limit: 5

參考： https://docs.oracle.com/javase/9/docs/api/java/nio/DoubleBuffer.html#rewind–

相關用法

注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 DoubleBuffer rewind() Method 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。