Java中的 IntBuffer asReadOnlyBuffer() 方法

Java.nio.IntBuffer 类的asReadOnlyBuffer()方法用于使用此缓冲区的内容创建一个新的只读 int 缓冲区。新缓冲区是此缓冲区的副本。因此，对此缓冲区内容所做的更改将在新缓冲区中可见。

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、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。如果此缓冲区本身是只读的，则此方法的行为方式与复制方法完全相同。

句法 ：

public abstract IntBuffer asReadOnlyBuffer()

返回值：此方法返回与此缓冲区内容相同的新的只读 int缓冲区。

下面是说明 asReadOnlyBuffer() 方法的示例：

示例 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 IntBuffer
        int capacity = 10;
  
        // Creating the IntBuffer
        try {
  
            // creating object of Intbuffer
            // and allocating size capacity
            IntBuffer ib = IntBuffer.allocate(capacity);
  
            // putting the value in Intbuffer
            ib.put(8);
            ib.put(2, 9);
            ib.rewind();
  
            // print the IntBuffer
            System.out.println("Original IntBuffer:  "
                               + Arrays.toString(ib.array()));
  
            // Creating a read-only copy of IntBuffer
            // using asReadOnlyBuffer() method
            IntBuffer IntBuffer = ib.asReadOnlyBuffer();
  
            // print the IntBuffer
            System.out.print("\nReadOnlyBuffer IntBuffer: ");
  
            while (IntBuffer.hasRemaining())
                System.out.print(IntBuffer.get() + ", ");
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出：

Original IntBuffer:  [8, 0, 9, 0, 0, 0, 0, 0, 0, 0]

ReadOnlyBuffer IntBuffer: 8, 0, 9, 0, 0, 0, 0, 0, 0, 0,

示例 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 ib
        int capacity1 = 10;
  
        // Declaring the capacity of the ib1
        int capacity2 = 5;
  
        // Creating the IntBuffer
        try {
   
            // creating object of Intbuffer ib
            // and allocating size capacity
            IntBuffer ib = IntBuffer.allocate(capacity1);
  
            // putting the value in ib
            ib.put(8);
            ib.put(2, 9);
            ib.rewind();
  
            // print the IntBuffer
            System.out.println("IntBuffer ib: "
                               + Arrays.toString(ib.array()));
  
            // ib1
            // creating object of Intbuffer ib1
            // and allocating size capacity
            IntBuffer ib1 = IntBuffer.allocate(capacity2);
  
            // putting the value in ib1
            ib1.put(1, 4);
            ib1.put(2, 6);
            ib1.rewind();
  
            // print the IntBuffer
            System.out.println("\nIntBuffer ib1:  "
                               + Arrays.toString(ib1.array()));
  
            // Creating a read-only copy of IntBuffer
            // using asReadOnlyBuffer() method
            IntBuffer readOnlyib = ib.asReadOnlyBuffer();
  
            // print the IntBuffer
            System.out.print("\nReadOnlyBuffer IntBuffer: ");
  
            while (readOnlyib.hasRemaining())
                System.out.print(readOnlyib.get() + ", ");
  
            // try to change readOnlyib
            System.out.println("\n\nTrying to get the array"
                               + " from ReadOnlyib for editing");
  
            int[] ibarr = readOnlyib.array();
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出：

IntBuffer ib: [8, 0, 9, 0, 0, 0, 0, 0, 0, 0]

IntBuffer ib1:  [0, 4, 6, 0, 0]

ReadOnlyBuffer IntBuffer: 8, 0, 9, 0, 0, 0, 0, 0, 0, 0, 

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