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:

IntBuffer ib is not backed by any array