Java ShortBuffer asReadOnlyBuffer()方法及示例

java.nio.ShortBuffer 类的 asReadOnlyBuffer() 方法是用来创建一个新的、只读的短缓冲区，其内容是这个缓冲区的。新的缓冲区是这个缓冲区的复制品。因此，对这个缓冲区的内容所做的改变将在新的缓冲区中可见。

由于新缓冲区是只读的，因此不允许对其内容进行任何修改。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。如果这个缓冲区本身是只读的，那么这个方法的行为与复制方法完全相同。

语法:

public abstract ShortBuffer asReadOnlyBuffer()

返回值 :该方法返回新的、 只读的短缓冲区 ，其内容与该缓冲区的内容相同。

下面是说明 asReadOnlyBuffer() 方法的例子。

程序1 :

// Java program to demonstrate
// asReadOnlyBuffer() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the ShortBuffer
        int capacity = 10;
  
        // Creating the ShortBuffer
        try {
  
            // creating object of shortbuffer
            // and allocating size capacity
            ShortBuffer sb = ShortBuffer.allocate(capacity);
  
            // putting the value in shortbuffer
            sb.put((short)856);
            sb.put(2, (short)961);
            sb.rewind();
  
            // print the ShortBuffer
            System.out.println("Original ShortBuffer: "
                               + Arrays.toString(sb.array()));
  
            // Creating a read-only copy of ShortBuffer
            // using asReadOnlyBuffer() method
            ShortBuffer shortBuffer = sb.asReadOnlyBuffer();
  
            // print the ShortBuffer
            System.out.print("\nReadOnlyBuffer ShortBuffer: ");
  
            while (shortBuffer.hasRemaining())
                System.out.print(shortBuffer.get() + ", ");
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出:

Original ShortBuffer: [856, 0, 961, 0, 0, 0, 0, 0, 0, 0]

ReadOnlyBuffer ShortBuffer: 856, 0, 961, 0, 0, 0, 0, 0, 0, 0,

程序2 :

// Java program to demonstrate
// asReadOnlyBuffer() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args) throws Exception
    {
  
        // Declaring the capacity of the sb
        int capacity1 = 10;
  
        // Declaring the capacity of the sb1
        int capacity2 = 5;
  
        // Creating the ShortBuffer
        try {
  
            //
            // sb
            //
            // creating object of shortbuffer sb
            // and allocating size capacity
            ShortBuffer sb = ShortBuffer.allocate(capacity1);
  
            // putting the value in sb
            sb.put((short)856);
            sb.put(2, (short)961);
            sb.rewind();
  
            // print the ShortBuffer
            System.out.println("ShortBuffer sb: "
                               + Arrays.toString(sb.array()));
  
            //
            // sb1
            //
            // creating object of shortbuffer sb1
            // and allocating size capacity
            ShortBuffer sb1 = ShortBuffer.allocate(capacity2);
  
            // putting the value in sb1
            sb1.put(1, (short)456);
            sb1.put(2, (short)645);
            sb1.rewind();
  
            // print the ShortBuffer
            System.out.println("\nShortBuffer sb1: "
                               + Arrays.toString(sb1.array()));
  
            // Creating a read-only copy of ShortBuffer
            // using asReadOnlyBuffer() method
            ShortBuffer readOnlySb = sb.asReadOnlyBuffer();
  
            // print the ShortBuffer
            System.out.print("\nReadOnlyBuffer FloatBuffer: ");
  
            while (readOnlySb.hasRemaining())
                System.out.print(readOnlySb.get() + ", ");
  
            // try to change readOnlySb
            System.out.println("\n\nTrying to get the array"
                               + " from ReadOnlyFb for editing");
  
            short[] sbarr = readOnlySb.array();
        }
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出:

ShortBuffer sb: [856, 0, 961, 0, 0, 0, 0, 0, 0, 0]

ShortBuffer sb1: [0, 456, 645, 0, 0]

ReadOnlyBuffer FloatBuffer: 856, 0, 961, 0, 0, 0, 0, 0, 0, 0, 

Trying to get the array from ReadOnlyFb for editing
Exception thrown: java.nio.ReadOnlyBufferException