Java中的 FloatBuffer asReadOnlyBuffer() 方法及示例

Java.nio.FloatBuffer 类的asReadOnlyBuffer()方法用于使用此缓冲区的内容创建一个新的只读浮点缓冲区。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 FloatBuffer asReadOnlyBuffer()

返回值：此方法返回与此缓冲区内容相同的新的只读浮点缓冲区。

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 FloatBuffer
        int capacity = 10;
  
        // Creating the FloatBuffer
        try {
  
            // creating object of floatbuffer
            // and allocating size capacity
            FloatBuffer fb = FloatBuffer.allocate(capacity);
  
            // putting the value in floatbuffer
            fb.put(8.56F);
            fb.put(2, 9.61F);
            fb.rewind();
  
            // print the FloatBuffer
            System.out.println("Original FloatBuffer:  "
                               + Arrays.toString(fb.array()));
  
            // Creating a read-only copy of FloatBuffer
            // using asReadOnlyBuffer() method
            FloatBuffer floatBuffer = fb.asReadOnlyBuffer();
  
            // print the FloatBuffer
            System.out.print("\nReadOnlyBuffer FloatBuffer: ");
  
            while (floatBuffer.hasRemaining())
                System.out.print(floatBuffer.get() + ", ");
        }
  
        catch (IllegalArgumentException e) {
  
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
  
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出：

Original FloatBuffer:  [8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

ReadOnlyBuffer FloatBuffer: 8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 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 fb
        int capacity1 = 10;
  
        // Declaring the capacity of the fb1
        int capacity2 = 5;
  
        // Creating the FloatBuffer
        try {
  
            //
            // fb
            //
            // creating object of floatbuffer fb
            // and allocating size capacity
            FloatBuffer fb = FloatBuffer.allocate(capacity1);
  
            // putting the value in fb
            fb.put(8.56F);
            fb.put(2, 9.61F);
            fb.rewind();
  
            // print the FloatBuffer
            System.out.println("FloatBuffer fb: "
                               + Arrays.toString(fb.array()));
  
            //
            // fb1
            //
            // creating object of floatbuffer fb1
            // and allocating size capacity
            FloatBuffer fb1 = FloatBuffer.allocate(capacity2);
  
            // putting the value in fb1
            fb1.put(1, 4.56F);
            fb1.put(2, 6.45F);
            fb1.rewind();
  
            // print the FloatBuffer
            System.out.println("\nFloatBuffer fb1:  "
                               + Arrays.toString(fb1.array()));
  
            // Creating a read-only copy of FloatBuffer
            // using asReadOnlyBuffer() method
            FloatBuffer readOnlyFb = fb.asReadOnlyBuffer();
  
            // print the FloatBuffer
            System.out.print("\nReadOnlyBuffer FloatBuffer: ");
  
            while (readOnlyFb.hasRemaining())
                System.out.print(readOnlyFb.get() + ", ");
  
            // try to change readOnlyFb
            System.out.println("\n\nTrying to get the array"
                               + " from ReadOnlyFb for editing");
  
            float[] fbarr = readOnlyFb.array();
        }
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出：

FloatBuffer fb: [8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

FloatBuffer fb1:  [0.0, 4.56, 6.45, 0.0, 0.0]

ReadOnlyBuffer FloatBuffer: 8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 

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