Java DoubleBuffer array()方法及示例

java.nio.DoubleBuffer 类的 array() 方法是用来返回支持这个缓冲区的双数组。对这个缓冲区内容的修改将导致返回的数组的内容被修改，反之亦然。在调用此方法之前，先使用Invoke()和hasArray()方法，以确保此缓冲区有一个可访问的支持阵列。

语法:

public final float[] array()

返回值： 该方法返回 支持该缓冲区的数组 。

异常： 如果这个缓冲区是由数组支持的，但是是只读的，这个方法会抛出 ReadOnlyBufferException 。

下面的程序说明了array()方法。

例子 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 DoubleBuffer
        int capacity = 10;
  
        // Creating the DoubleBuffer
        try {
  
            // creating object of Doublebuffer
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.allocate(capacity);
  
            // putting the value in Doublebuffer
            db.put(8.56F);
            db.put(2, 9.61F);
            db.rewind();
  
            // getting array from db DoubleBuffer using array() method
            double[] dbb = db.array();
  
            // printing the DoubleBuffer db
            System.out.println("DoubleBuffer:  "
                               + Arrays.toString(dbb));
        }
  
        catch (IllegalArgumentException e) {
  
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
  
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出:

DoubleBuffer:  [8.5600004196167, 0.0, 9.609999656677246, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

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 db
        int capacity1 = 10;
  
        // Declaring the capacity of the db1
        int capacity2 = 5;
  
        // Creating the DoubleBuffer
        try {
            //
            // db
            //
            // creating object of Doublebuffer db
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.allocate(capacity1);
  
            // putting the value in db
            db.put(9.56F);
            db.put(2, 7.61F);
            db.put(3, 4.61F);
            db.rewind();
  
            // print the DoubleBuffer
            System.out.println("DoubleBuffer db: "
                               + Arrays.toString(db.array()));
  
            //
            // db1
            //
            // creating object of Doublebuffer db1
            // and allocating size capacity
            DoubleBuffer db1 = DoubleBuffer.allocate(capacity2);
  
            // putting the value in db1
            db1.put(1, 4.56F);
            db1.put(2, 6.45F);
            db1.rewind();
  
            // print the DoubleBuffer
            System.out.println("\nDoubleBuffer db1:  "
                               + Arrays.toString(db1.array()));
  
            // Creating a read-only copy of DoubleBuffer
            // using asReadOnlyBuffer() method
            DoubleBuffer readOnlyDb = db.asReadOnlyBuffer();
  
            // print the DoubleBuffer
            System.out.print("\nReadOnlyBuffer DoubleBuffer: ");
  
            while (readOnlyDb.hasRemaining())
                System.out.print(readOnlyDb.get() + ", ");
  
            // try to change readOnlyDb
            System.out.println("\n\nTrying to get the array"
                               + " from ReadOnlyDb for editing");
            Arrays.toString(readOnlyDb.array());
        }
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出:

DoubleBuffer db: [9.5600004196167, 0.0, 7.610000133514404, 4.610000133514404, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

DoubleBuffer db1:  [0.0, 4.559999942779541, 6.449999809265137, 0.0, 0.0]

ReadOnlyBuffer DoubleBuffer: 9.5600004196167, 0.0, 7.610000133514404, 4.610000133514404, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 

Trying to get the array from ReadOnlyDb for editing
Exception thrown: java.nio.ReadOnlyBufferException