Java中的DoubleBuffer duplicate()方法及示例

Java.nio.DoubleBuffer类的duplicate()方法用于创建一个共享给定缓冲区内容的新浮点缓冲区。

新缓冲区的内容就是这个缓冲区的内容。此缓冲区内容的更改将在新缓冲区中可见，反之亦然；两个缓冲区的位置、限制和标记值将是独立的。

新缓冲区的容量、限制、位置和标记值将与此缓冲区的相同。当且仅当此缓冲区是直接的时，新缓冲区将是直接的，并且当且仅当此缓冲区是只读的时，它将是只读的。

句法 ：

public abstract DoubleBuffer duplicate()

返回值：此方法返回新的双缓冲区，该缓冲区带有先前的双缓冲区内容

以下是说明duplicate()方法的示例：

方案一：

// Java program to demonstrate
// duplicate() method
// Using direct Doublebuffer
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the DoubleBuffer
        int capacity = 10;
  
        // Creating the DoubleBuffer
        try {
  
            // creating object of Doublebuffer
            // and allocating size capacity
            DoubleBuffer db1 = DoubleBuffer.allocate(capacity);
  
            // putting the value in Doublebuffer
            db1.put(8.56F);
            db1.put(2, 9.61F);
            db1.rewind();
  
            // print the Original DoubleBuffer
            System.out.println("Original DoubleBuffer:  "
                               + Arrays.toString(db1.array()));
  
            // Creating a duplicate copy of DoubleBuffer
            // using duplicate() method
            DoubleBuffer db2 = db1.duplicate();
  
            // print the duplicate copy of DoubleBuffer
            System.out.print("\nDuplicate DoubleBuffer: "
                             + Arrays.toString(db2.array()));
        }
  
        catch (IllegalArgumentException e) {
  
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
  
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出：

Original DoubleBuffer:  [8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

Duplicate DoubleBuffer: [8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

示例 2：

// Java program to demonstrate
// duplicate() method
// using read-onlyDoublebuffer
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the DoubleBuffer
        int capacity = 10;
  
        // Creating the DoubleBuffer
        try {
  
            // creating object of Doublebuffer
            // and allocating size capacity
            DoubleBuffer db1 = DoubleBuffer.allocate(capacity);
  
            // putting the value in Doublebuffer
            db1.put(8.56F);
            db1.put(2, 9.61F);
            db1.rewind();
  
            // print the Original DoubleBuffer
            System.out.println("Original DoubleBuffer:  "
                               + Arrays.toString(db1.array()));
  
            // Creating a read-only copy of DoubleBuffer
            // using asReadOnlyBuffer() method
            DoubleBuffer readonly = db1.asReadOnlyBuffer();
  
            // print the read-only copy of DoubleBuffer
            System.out.print("\nread-only DoubleBuffer:  ");
            while (readonly.hasRemaining())
                System.out.print(readonly.get() + ", ");
            System.out.println("");
  
            // Rewinding the readonly DoubleBuffer
            readonly.rewind();
  
            // Creating a duplicate copy of DoubleBuffer
            // using duplicate() method
            DoubleBuffer db2 = readonly.duplicate();
  
            // print the duplicate copy of DoubleBuffer
            System.out.print("\nduplicate copy of read-only DoubleBuffer:  ");
  
            while (db2.hasRemaining())
                System.out.print(db2.get() + ", ");
            System.out.println("");
        }
  
        catch (IllegalArgumentException e) {
  
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
  
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出：

Original DoubleBuffer:  [8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

read-only DoubleBuffer:  8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 

duplicate copy of read-only DoubleBuffer:  8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,