Java中的ShortBuffer compact（）方法及其示例-yiteyi-C++库

这个 紧凑的 方法 JAVA尼奥。短缓冲区 类用于压缩给定的缓冲区。缓冲区当前位置与其限制之间的短路（如果有）将复制到缓冲区的开头。也就是说，索引p=位置（）处的短路被复制到索引0，索引p+1处的短路被复制到索引1，依此类推，直到索引限制（）处的短路被复制到索引n=限制（）–1–p。然后缓冲区的位置被设置为n+1，其限制被设置为其容量。标记（如果定义）将被丢弃。缓冲区的位置设置为复制的短路数，而不是零，这样调用此方法后，可以立即调用另一个相对put方法。

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语法 :

public abstract ShortBuffer compact()

返回值 ：此方法返回 新短缓冲区 与此缓冲区的内容相同。

例外：此方法抛出 ReadOnlyBufferException ，如果此缓冲区是只读的。

下面的程序说明了 紧凑的 方法：

方案1 :

                     // Java program to demonstrate                   
                     // compact() method                   
                             
                     import                               java.nio.*;                   
                     import                               java.util.*;                   
                             
                     public                               class                               GFG {                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                             
                                         // Declaring the capacity of the ShortBuffer                   
                                         int                               capacity =                               10                               ;                   
                             
                                         // Creating the ShortBuffer                   
                             
                                         // creating object of shortbuffer                   
                                         // and allocating size capacity                   
                                         ShortBuffer sb = ShortBuffer.allocate(capacity);                   
                             
                                         // putting the value in shortbuffer                   
                                         sb.put((                               short                               )                               856                               );                   
                                         sb.put((                               short                               )                               961                               );                   
                                         sb.put((                               short                               )                               54                               );                   
                             
                                         // print the ShortBuffer                   
                                         System.out.println(                               "Original ShortBuffer: "                   
                                         + Arrays.toString(sb.array()));                   
                             
                                         System.out.println(                               "Position: "                               + sb.position());                   
                             
                                         System.out.println(                               "limit: "                               + sb.limit());                   
                             
                                         // Creating a compacted ShortBuffer of same ShortBuffer                   
                                         // using compact() method                   
                                         ShortBuffer shortBuffer = sb.compact();                   
                             
                                         // print the ShortBuffer                   
                                         System.out.println(                               "Compacted ShortBuffer: "                   
                                         + Arrays.toString(shortBuffer.array()));                   
                             
                                         System.out.println(                               "Position: "                               + shortBuffer.position());                   
                             
                                         System.out.println(                               "limit: "                               + shortBuffer.limit());                   
                             
                                         // putting the value in compacted shortbuffer                   
                                         shortBuffer.put((                               short                               )                               961                               );                   
                             
                                         // print the ShortBuffer                   
                                         System.out.println(                               "Updated Compacted ShortBuffer: "                   
                                         + Arrays.toString(shortBuffer.array()));                   
                                         System.out.println(                               "Position: "                               + shortBuffer.position());                   
                                         System.out.println(                               "limit: "                               + shortBuffer.limit());                   
                                         }                   
                     }                   

输出：

Original ShortBuffer: [856, 961, 54, 0, 0, 0, 0, 0, 0, 0]
Position: 3
limit: 10

Compacted ShortBuffer: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
Position: 7
limit: 10

Updated Compacted ShortBuffer: [0, 0, 0, 0, 0, 0, 0, 961, 0, 0]
Position: 8
limit: 10

项目2： 演示ReadOnlyBufferException。

                     // Java program to demonstrate                   
                     // compact() method                   
                             
                     import                               java.nio.*;                   
                     import                               java.util.*;                   
                             
                     public                               class                               GFG {                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                             
                                         // Declaring the capacity of the ShortBuffer                   
                                         int                               capacity =                               10                               ;                   
                             
                                         // Creating the ShortBuffer                   
                                         try                               {                   
                             
                                         // creating object of ShortBuffer                   
                                         // and allocating size capacity                   
                                         ShortBuffer sb = ShortBuffer.allocate(capacity);                   
                             
                                         // putting the value in floatbuffer                   
                                         sb.put((                               short                               )                               856                               );                   
                                         sb.put((                               short                               )                               961                               );                   
                                         sb.put((                               short                               )                               6010                               );                   
                                         sb.rewind();                   
                             
                                         // Creating a read-only copy of ShortBuffer                   
                                         // using asReadOnlyBuffer() method                   
                                         ShortBuffer sb1 = sb.asReadOnlyBuffer();                   
                             
                                         // print the ReadOnlyBuffer                   
                                         System.out.print(                               "ReadOnlyBuffer ShortBuffer: "                               );                   
                                         while                               (sb1.hasRemaining())                   
                                         System.out.print(sb1.get() +                               ", "                               );                   
                                         System.out.println(                               ""                               );                   
                             
                                         // print the Position of ShortBuffer sb                   
                                         System.out.println(                               "Position: "                               + sb.position());                   
                             
                                         // print the Limit of ShortBuffer fb                   
                                         System.out.println(                               "limit: "                               + sb.limit());                   
                             
                                         // Creating a compacted ShortBuffer of same ReadOnlyBuffer                   
                                         // using compact() method                   
                                         System.out.println(                               "Trying to compact the ReadOnlyBuffer sb1"                               );                   
                             
                                         ShortBuffer floatBuffer = sb1.compact();                   
                                         }                   
                             
                                         catch                               (IllegalArgumentException e) {                   
                                         System.out.println(                               "Exception throws "                               + e);                   
                                         }                   
                             
                                         catch                               (ReadOnlyBufferException e) {                   
                                         System.out.println(                               "Exception throws "                               + e);                   
                                         }                   
                                         }                   
                     }                   

输出：

ReadOnlyBuffer ShortBuffer: 856, 961, 6010, 0, 0, 0, 0, 0, 0, 0, 

Position: 0

limit: 10

Trying to compact the ReadOnlyBuffer sb1
Exception throws java.nio.ReadOnlyBufferException

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