当前位置: 首页>>代码示例>>用法及示例精选>>正文


Java - ByteBuffer wrap()用法及代码示例

wrap(byte[] array)

java.nio.ByteBuffer类的wrap()方法用于将字节数组包装到缓冲区中。新缓冲区将由给定的字节数组支持;也就是说,对缓冲区的修改将导致数组被修改,反之亦然。新缓冲区的容量和限制为array.length,位置为零,标记未定义。它的支持数组将是给定的数组,其数组偏移量将为零。

用法:

public static ByteBuffer wrap(float[] array)

参数:此方法将float数组作为参数,它将是支持此缓冲区的数组。


返回值:此方法返回新的字节缓冲区。

下面是说明wrap()方法的示例:

范例1:

// Java program to demonstrate 
// wrap() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Declare and initialize the byte array 
        byte[] bbb = { 10, 20, 30 }; 
  
        // print the byte array length 
        System.out.println("Array length : "
                           + bbb.length); 
  
        // print the byte array element 
        System.out.println("\nArray element : "
                           + Arrays.toString(bbb)); 
  
        // wrap the byte array into byteBuffer 
        // using wrap() method 
        ByteBuffer byteBuffer = ByteBuffer.wrap(bbb); 
  
        // Rewind the ByteBuffer 
        byteBuffer.rewind(); 
  
        // print the byte buffer 
        System.out.println("\nbyteBuffer : "
                           + Arrays.toString(byteBuffer.array())); 
  
        // print the ByteBuffer capacity 
        System.out.println("\nbyteBuffer capacity : "
                           + byteBuffer.capacity()); 
  
        // print the ByteBuffer position 
        System.out.println("\nbyteBuffer position:  "
                           + byteBuffer.position()); 
    } 
}
输出:
Array length : 3

Array element : [10, 20, 30]

byteBuffer : [10, 20, 30]

byteBuffer capacity : 3

byteBuffer position:  0

参考: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#wrap-byte:A-

wrap(byte[] array, int offset, int length)

新缓冲区将由给定的字节数组支持;也就是说,对缓冲区的修改将导致数组被修改,反之亦然。新缓冲区的容量将为array.length,其位置将偏移,其限制将为offset + length,其标记将是不确定的。它的支持数组将是给定的数组,其数组偏移量将为零。

用法:

public static ByteBuffer wrap(byte[] array, 
                          int offset, int length)

参数:此方法采用以下参数:

  • array:将支持新缓冲区的数组。
  • offset:要使用的子数组的偏移量;必须为非负数,且不得大于array.length。新缓冲区的位置将设置为此值。
  • length:要使用的子数组的长度;必须为非负且不大于array.length –偏移量。新缓冲区的限制将设置为偏移量+长度。

返回值:此方法返回新的字节缓冲区。

抛出:此方法抛出IndexOutOfBoundsException(如果offset和length参数的前提条件不成立)。


下面是说明wrap()方法的示例:

范例1:

// Java program to demonstrate 
// wrap() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declare and initialize the byte array 
        byte[] bbb = { 10, 20, 30 }; 
  
        // print the byte array length 
        System.out.println("Array length : "
                           + bbb.length); 
  
        // print the byte array element 
        System.out.println("\nArray element : "
                           + Arrays.toString(bbb)); 
  
        // wrap the byte array into ByteBuffer 
        // using wrap() method 
        ByteBuffer byteBuffer = ByteBuffer.wrap(bbb, 0, 
                                                bbb.length); 
  
        // Rewind the bytebuffer 
        byteBuffer.rewind(); 
  
        // print the byte buffer 
        System.out.println("\nbyteBuffer : "
                           + Arrays.toString(byteBuffer.array())); 
  
        // print the ByteBuffer capacity 
        System.out.println("\nbyteBuffer capacity : "
                           + byteBuffer.capacity()); 
  
        // print the ByteBuffer position 
        System.out.println("\nbyteBuffer position:  "
                           + byteBuffer.position()); 
    } 
}
输出:
Array length : 3

Array element : [10, 20, 30]

byteBuffer : [10, 20, 30]

byteBuffer capacity : 3

byteBuffer position:  0

范例2:演示NullPointerException

// Java program to demonstrate 
// asReadOnlyBuffer() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declare and initialize the byte array 
        byte[] bbb = { 10, 20, 30 }; 
  
        // print the byte array length 
        System.out.println("Array length : " + bbb.length); 
  
        // print the byte array element 
        System.out.println("\nArray element : " + Arrays.toString(bbb)); 
  
        try { 
            // wrap the byte array into byteBuffer 
            // using wrap() method 
            System.out.println("\nHere "
                               + "offset and length does not hold"
                               + " the required condition "); 
            ByteBuffer byteBuffer = ByteBuffer.wrap(bbb, 
                                                    1, 
                                                    bbb.length); 
  
            // Rewind the bytebuffer 
            byteBuffer.rewind(); 
  
            // print the byte buffer 
            System.out.println("\nbyteBuffer : "
                               + Arrays.toString(byteBuffer.array())); 
  
            // print the byteBuffer capacity 
            System.out.println("\nbytebuffer capacity : "
                               + byteBuffer.capacity()); 
  
            // print the byteBuffer position 
            System.out.println("\nbytebuffer position:  "
                               + byteBuffer.position()); 
        } 
        catch (IndexOutOfBoundsException e) { 
            System.out.println("Exception throws:  " + e); 
        } 
    } 
}
输出:
Array length : 3

Array element : [10, 20, 30]

Here offset and length does not hold the required condition 
Exception throws:  java.lang.IndexOutOfBoundsException

参考: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#wrap-byte:A-int-int-



相关用法

注:本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 ByteBuffer wrap() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文的传播和使用请遵循“署名-相同方式共享 4.0 国际 (CC BY-SA 4.0)”协议。