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 editingException thrown: java.nio.ReadOnlyBufferException