Java CharBuffer duplicate()方法

java.nio.CharBuffer 类的 duplicate() 方法用于创建一个新的 char缓冲区 ，共享给定的缓冲区的内容。

新的缓冲区的内容将是这个缓冲区的内容。这个缓冲区的内容的变化将在新的缓冲区中可见，反之亦然；两个缓冲区的位置、极限和标记值将是独立的。

新缓冲区的容量、极限、位置和标记值将与这个缓冲区的相同。当且仅当这个缓冲区是直接的，新的缓冲区将是直接的；当且仅当这个缓冲区是只读的，它将是只读的。

语法

public abstract CharBuffer duplicate()

返回值： 该方法返回 新的char缓冲区 ，该缓冲区承载了 之前的char缓冲区 内容。

下面是一些例子来说明 duplicate() 方法。

例子1： 直接使用charbuffer

// Java program to demonstrate
// duplicate() method
// Using direct intbuffer
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the CharBuffer
        int capacity = 10;
  
        // Creating the CharBuffer
        try {
  
            // creating object of Intbuffer
            // and allocating size capacity
            CharBuffer cb1 = CharBuffer.allocate(capacity);
  
            // putting the value in Intbuffer
            cb1.put('a');
            cb1.put(2, 'b');
            cb1.rewind();
  
            // print the Original CharBuffer
            System.out.println("Original CharBuffer: "
                               + Arrays.toString(cb1.array()));
  
            // Creating a duplicate copy of CharBuffer
            // using duplicate() method
            CharBuffer cb2 = cb1.duplicate();
  
            // print the duplicate copy of CharBuffer
            System.out.print("Duplicate CharBuffer: "
                             + Arrays.toString(cb2.array()));
        }
  
        catch (IllegalArgumentException e) {
  
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
  
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出:

Original CharBuffer: [a, , b, , , , , , , ]
Duplicate CharBuffer: [a, , b, , , , , , , ]

例2： 使用只读的intbuffer

// Java program to demonstrate
// duplicate() method
// using read-onlyIntbuffer
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the CharBuffer
        int capacity = 10;
  
        // Creating the CharBuffer
        try {
  
            // creating object of Intbuffer
            // and allocating size capacity
            CharBuffer cb1 = CharBuffer.allocate(capacity);
  
            // putting the value in Intbuffer
            cb1.put('a');
            cb1.put(2, 'b');
            cb1.rewind();
  
            // print the Original CharBuffer
            System.out.println("Original CharBuffer: "
                               + Arrays.toString(cb1.array()));
  
            // Creating a read-only copy of CharBuffer
            // using asReadOnlyBuffer() method
            CharBuffer readonly = cb1.asReadOnlyBuffer();
  
            // print the read-only copy of CharBuffer
            System.out.print("read-only CharBuffer: ");
            while (readonly.hasRemaining())
                System.out.print(readonly.get() + ", ");
            System.out.println("");
  
            // Rewinding the readonly CharBuffer
            readonly.rewind();
  
            // Creating a duplicate copy of CharBuffer
            // using duplicate() method
            CharBuffer cb2 = readonly.duplicate();
  
            // print the duplicate copy of CharBuffer
            System.out.print("duplicate copy of read-only CharBuffer: ");
  
            while (cb2.hasRemaining())
                System.out.print(cb2.get() + ", ");
            System.out.println("");
        }
  
        catch (IllegalArgumentException e) {
  
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
  
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出:

Original CharBuffer: [a, , b, , , , , , , ]
read-only CharBuffer: a, , b, , , , , , , , 
duplicate copy of read-only CharBuffer: a, , b, , , , , , , ,