Java 中的字节缓冲包装()方法，示例
原文:https://www . geeksforgeeks . org/bytebuffer-wrap-method-in-Java-with-examples/
换行(字节[]数组)
类的 wrap() 方法用于将字节数组包装到缓冲区中。给定的字节数组将支持新的缓冲区；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将为 array.length，其位置将为零，其标记将未定义。它的后备数组将是给定的数组，并且它的数组偏移量将为零。
语法:
public static ByteBuffer wrap(float[] array)
参数:该方法以一个浮点数组作为参数，该数组将支持该缓冲区。
返回值:这个方法返回新的字节缓冲区。
以下是说明包裹()方法的示例:
示例 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-
换行(字节[]数组，int 偏移量，int 长度)
给定的字节数组将支持新的缓冲区；也就是说，对缓冲区的修改将导致数组被修改，反之亦然。新缓冲区的容量将是 array.length，它的位置将被偏移，它的限制将是 offset + length，它的标记将是未定义的。它的后备数组将是给定的数组，并且它的数组偏移量将为零。
语法:
public static ByteBuffer wrap(byte[] array,
int offset, int length)
参数:此方法取以下参数:
- Array: The array of the new buffer will be backed up.
- Offset: Offset of the subarray to be used; Must be non-negative and not greater than the array length. The location of the new buffer will be set to this value.
- Length: The length of the subarray to be used; Must be non-negative and not greater than array.length–offset. The limit of the new buffer will be set to offset+length.
返回值:这个方法返回新的字节缓冲区。
抛出:此方法抛出指数超出边界异常(如果偏移和长度参数的前提条件不成立)。
下面是说明 wrap()方法的示例:
示例 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
示例 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-
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