Java中的FloatBuffer asReadOnlyBuffer（）方法及其示例-yiteyi-C++库

这个 asReadOnlyBuffer（） 方法 JAVA尼奥。浮动缓冲类 用于创建 新的只读浮点缓冲区 用这个缓冲区的内容。新缓冲区是此缓冲区的副本。因此，对该缓冲区内容所做的更改将在新缓冲区中可见。

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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。两个缓冲器的位置、极限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。

语法：

public abstract FloatBuffer asReadOnlyBuffer()

返回值： 此方法返回 新的只读浮点缓冲区 与此缓冲区的内容相同。

下面是演示asReadOnlyBuffer（）方法的示例：

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(                               "ReadOnlyBuffer 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(                               "FloatBuffer 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(                               "ReadOnlyBuffer FloatBuffer: "                               );                   
                             
                                         while                               (readOnlyFb.hasRemaining())                   
                                         System.out.print(readOnlyFb.get() +                               ", "                               );                   
                             
                                         // try to change readOnlyFb                   
                                         System.out.println(                               "Trying 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

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