Java Buffer array()用法及代码示例

java.nio.Buffer类的array()方法用于返回支持已采用缓冲区的数组。此方法旨在使array-backed缓冲区更有效地传递给本机代码。具体的子类为此方法提供了更强类型的返回值。

对该缓冲区内容的修改将导致返回数组的内容被修改，反之亦然。在调用此方法之前，请先调用hasArray方法，以确保此缓冲区具有可访问的后备数组。

用法:

public abstract Object array()

返回值：此方法返回支持此缓冲区的数组。

异常：如果此缓冲区由数组支持但为只读，则此方法引发ReadOnlyBufferException。

下面是说明array()方法的示例：

范例1：

// Java program to demonstrate 
// array() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 4; 
  
        // Creating the ByteBuffer 
        try { 
  
            // creating object of ByteBuffer 
            // and allocating size capacity 
            ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
            // putting the int to byte typecast 
            // value in ByteBuffer 
            bb.put((byte)20); 
            bb.put((byte)30); 
            bb.put((byte)40); 
            bb.put((byte)50); 
  
            // Typecasting ByteBuffer into Buffer 
            Buffer bb1 = (Buffer)bb; 
  
            // getting array that backs this buffer 
            // using array() method 
            byte[] arr = (byte[])bb1.array(); 
  
            // print the array 
            System.out.print("array is:["); 
            for (int i = 0; i < arr.length; i++) 
                System.out.print(" " + arr[i]); 
            System.out.print(" ]"); 
        } 
  
        catch (ReadOnlyBufferException e) { 
  
            System.out.println("Exception throws:"
                               + e); 
        } 
    } 
}

输出：

array is:[ 20 30 40 50 ]

范例2：

// Java program to demonstrate 
// array() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 4; 
  
        // Creating the ByteBuffer 
        try { 
  
            // creating object of ByteBuffer 
            // and allocating size capacity 
            ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
            // putting the int to byte typecast 
            // value in ByteBuffer 
            bb.put((byte)20); 
            bb.put((byte)30); 
            bb.put((byte)40); 
            bb.put((byte)50); 
  
            // Creating a read-only copy of ByteBuffer 
            // using asReadOnlyBuffer() method 
            ByteBuffer bb1 = bb.asReadOnlyBuffer(); 
  
            // Typecasting Read only ByteBuffer 
            // into Read-only Buffer 
            Buffer buffer = (Buffer)bb1; 
  
            // getting array that backs this buffer 
            // using array() method 
            byte[] arr = (byte[])buffer.array(); 
  
            // print the array 
            System.out.print("array is:["); 
            for (int i = 0; i < arr.length; i++) 
                System.out.print(" " + arr[i]); 
            System.out.print(" ]"); 
        } 
  
        catch (ReadOnlyBufferException e) { 
  
            System.out.println("buffer is backed by "
                               + "an array but is read-only"); 
            System.out.println("Exception throws:" + e); 
        } 
    } 
}

输出：

buffer is backed by an array but is read-only
Exception throws:java.nio.ReadOnlyBufferException

参考： https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.html#array-

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注：本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 Buffer array() methods in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。