Java中的IntBuffer compact（）方法-yiteyi-C++库

这个 紧凑的 方法 JAVA尼奥。IntBuffer 类用于压缩给定的缓冲区。

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缓冲区当前位置与其限制之间的值将复制到缓冲区的开头。然后将缓冲器的位置设置为n+1，并将其限制设置为其容量。缓冲区的位置设置为复制的浮点数。

语法：

public abstract IntBuffer compact()

返回值： 此方法返回 新IntBuffer 与此缓冲区的内容相同。

例外情况： 这个方法抛出了 ReadOnlyBufferException ，如果此缓冲区是只读的。

下面的程序说明了 紧凑的 方法：

例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 IntBuffer                   
                                         int                               capacity =                               10                               ;                   
                             
                                         // Creating the IntBuffer                   
                             
                                         // creating object of Intbuffer                   
                                         // and allocating size capacity                   
                                         IntBuffer ib = IntBuffer.allocate(capacity);                   
                             
                                         // putting the value in Intbuffer                   
                                         ib.put(                               8                               );                   
                                         ib.put(                               9                               );                   
                                         ib.put(                               9                               );                   
                             
                                         // print the IntBuffer                   
                                         System.out.println(                               "Original IntBuffer: "                   
                                         + Arrays.toString(ib.array()));                   
                             
                                         System.out.println(                               "Position: "                               + ib.position());                   
                             
                                         System.out.println(                               "limit: "                               + ib.limit());                   
                             
                                         // Creating a compacted  IntBuffer of same IntBuffer                   
                                         // using compact() method                   
                                         IntBuffer IntBuffer = ib.compact();                   
                             
                                         // print the IntBuffer                   
                                         System.out.println(                               "Compacted IntBuffer: "                   
                                         + Arrays.toString(IntBuffer.array()));                   
                             
                                         System.out.println(                               "Position: "                               + IntBuffer.position());                   
                             
                                         System.out.println(                               "limit: "                               + IntBuffer.limit());                   
                             
                                         // putting the value in compacted Intbuffer                   
                                         IntBuffer.put(                               9                               );                   
                             
                                         // print the IntBuffer                   
                                         System.out.println(                               "Updated Compacted IntBuffer: "                   
                                         + Arrays.toString(IntBuffer.array()));                   
                                         System.out.println(                               "Position: "                               + IntBuffer.position());                   
                                         System.out.println(                               "limit: "                               + IntBuffer.limit());                   
                                         }                   
                     }                   

输出：

Original IntBuffer: [8, 9, 9, 0, 0, 0, 0, 0, 0, 0]
Position: 3
limit: 10

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

Updated Compacted IntBuffer: [0, 0, 0, 0, 0, 0, 0, 9, 0, 0]
Position: 8
limit: 10

例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 IntBuffer                   
                                         int                               capacity =                               10                               ;                   
                             
                                         // Creating the IntBuffer                   
                                         try                               {                   
                             
                                         // creating object of IntBuffer                   
                                         // and allocating size capacity                   
                                         IntBuffer ib = IntBuffer.allocate(capacity);                   
                             
                                         // putting the value in Intbuffer                   
                                         ib.put(                               8                               );                   
                                         ib.put(                               9                               );                   
                                         ib.put(                               9                               );                   
                                         ib.rewind();                   
                             
                                         // Creating a read-only copy of IntBuffer                   
                                         // using asReadOnlyBuffer() method                   
                                         IntBuffer ib1 = ib.asReadOnlyBuffer();                   
                             
                                         // print the ReadOnlyBuffer                   
                                         System.out.print(                               "ReadOnlyBuffer IntBuffer: "                               );                   
                             
                                         while                               (ib1.hasRemaining())                   
                                         System.out.print(ib1.get() +                               ", "                               );                   
                                         System.out.println(                               ""                               );                   
                             
                                         // print the Position of IntBuffer ib                   
                                         System.out.println(                               "Position: "                               + ib.position());                   
                             
                                         // print the Limit of IntBuffer ib                   
                                         System.out.println(                               "limit: "                               + ib.limit());                   
                             
                                         // Creating a compacted  IntBuffer of same ReadOnlyBuffer                   
                                         // using compact() method                   
                                         System.out.println(                               "Trying to compact the ReadOnlyBuffer ib1"                               );                   
                             
                                         IntBuffer IntBuffer = ib1.compact();                   
                                         }                   
                             
                                         catch                               (IllegalArgumentException e) {                   
                                         System.out.println(                               "Exception throws "                               + e);                   
                                         }                   
                             
                                         catch                               (ReadOnlyBufferException e) {                   
                                         System.out.println(                               "Exception throws "                               + e);                   
                                         }                   
                                         }                   
                     }                   

输出：

ReadOnlyBuffer IntBuffer: 8, 9, 9, 0, 0, 0, 0, 0, 0, 0, 

Position: 0

limit: 10

Trying to compact the ReadOnlyBuffer ib1
Exception throws java.nio.ReadOnlyBufferException

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