Java IntBuffer hasArray()方法

java.nio.IntBuffer 类的 hasArray() 方法是用来确保给定的缓冲区是否有一个可访问的int数组作为支持。如果这个缓冲区有一个可访问的支持数组，它就返回true，否则就返回false。如果该方法返回true，那么可以安全地调用array()和arrayOffset()方法，因为它们在支持数组上工作。

语法

public final boolean hasArray()

返回值： 当且仅当这个缓冲区是由一个数组支持的并且不是只读的时候，这个方法将返回true。否则它将返回false。

下面是说明 hasArray() 方法的例子。

例子1： 当缓冲区由一个数组支持时

// 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

例子2： 当缓冲区没有数组支持的时候

// 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: