Java FloatBuffer asReadOnlyBuffer()方法及示例

java.nio.FloatBuffer类的asReadOnlyBuffer()方法用于用这个缓冲区的内容创建一个新的、只读的浮点数缓冲区。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。

由于新的缓冲区是只读的，因此对其内容的任何修改都是不允许的。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 FloatBuffer asReadOnlyBuffer()

返回值： 该方法返回新的、只读的Float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。

例子 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,

例子 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