Java FloatBuffer hasArray()方法及示例

java.nio.FloatBuffer 类的 hasArray() 方法用于确保给定的缓冲区是否有一个可访问的浮点数组作为支持。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： 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 FloatBuffer        int capacity = 10;          // Creating the FloatBuffer        try {              // creating object of floatbuffer            // and allocating size capacity            FloatBuffer fb = FloatBuffer.allocate(capacity);              // putting the value in floatbuffer            fb.put(8.56F);            fb.put(2, 9.61F);            fb.rewind();              // checking FloatBuffer fb is backed by array or not            boolean isArray = fb.hasArray();              // checking if else condition            if (isArray)                System.out.println("FloatBuffer fb is"                                   + " backed by array");            else                System.out.println("FloatBuffer fb is"                                   + " not backed by any array");        }          catch (IllegalArgumentException e) {            System.out.println("IllegalArgumentException catched");        }          catch (ReadOnlyBufferException e) {            System.out.println("ReadOnlyBufferException catched");        }    }}

输出。

FloatBuffer fb is backed by array

例子2： 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 FloatBuffer        int capacity = 10;          // Creating the FloatBuffer        try {              // creating object of floatbuffer            // and allocating size capacity            FloatBuffer fb = FloatBuffer.allocate(capacity);              // putting the value in floatbuffer            fb.put(8.56F);            fb.put(2, 9.61F);            fb.rewind();              // Creating a read-only copy of FloatBuffer            // using asReadOnlyBuffer() method            FloatBuffer fb1 = fb.asReadOnlyBuffer();              // checking FloatBuffer fb is backed by array or not            boolean isArray = fb1.hasArray();              // checking if else condition            if (isArray)                System.out.println("FloatBuffer fb is"                                   + " backed by array");            else                System.out.println("FloatBuffer fb is"                                   + " not backed by any array");        }          catch (IllegalArgumentException e) {            System.out.println("IllegalArgumentException catched");        }          catch (ReadOnlyBufferException e) {            System.out.println("ReadOnlyBufferException catched");        }    }}

输出。

FloatBuffer fb is not backed by any array