Java中的 IntBuffer hasArray() 方法

Java.nio.IntBuffer类的hasArray()方法用于确保给定缓冲区是否由可访问的 int 数组支持。如果此缓冲区有可访问的支持数组，则返回 true，否则返回 false。如果此方法返回 true，则可以安全地调用 array() 和 arrayOffset() 方法，因为它们在后备数组上工作。

句法：

public final boolean hasArray()

返回值：当且仅当此缓冲区由数组支持并且不是只读的时，此方法才会返回true 。否则返回false 。

下面是说明hasArray()方法的示例：

示例 1：当缓冲区由数组支持时

// Java program to demonstrate
// hasArray() 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(4);
            ib.put(2, 9);
            ib.rewind();
  
            // checking IntBuffer ib is backed by array or not
            boolean isArray = ib.hasArray();
  
            // checking if else condition
            if (isArray)
                System.out.println("IntBuffer ib is"
                                   + " backed by array");
            else
                System.out.println("IntBuffer ib is"
                                   + " not backed by any array");
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出：

IntBuffer ib is backed by array

示例 2：当缓冲区没有数组支持时

// Java program to demonstrate
// hasArray() 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(2, 9);
            ib.rewind();
  
            // Creating a read-only copy of IntBuffer
            // using asReadOnlyBuffer() method
            IntBuffer ib1 = ib.asReadOnlyBuffer();
  
            // checking IntBuffer ib is backed by array or not
            boolean isArray = ib1.hasArray();
  
            // checking if else condition
            if (isArray)
                System.out.println("IntBuffer ib is"
                                   + " backed by array");
            else
                System.out.println("IntBuffer ib is"
                                   + " not backed by any array");
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("IllegalArgumentException catched");
        }
  
        catch (ReadOnlyBufferException e) {
            System.out.println("ReadOnlyBufferException catched");
        }
    }
}

输出：

IntBuffer ib is not backed by any array