Java CharBuffer hasArray()用法及代码示例

java.nio.CharBuffer类的hasArray()方法用于确保给定缓冲区是否由可访问的char数组支持。如果此缓冲区有可访问的后备数组，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，因为它们在支持数组上起作用。

用法:

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：

范例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 CharBuffer 
        int capacity = 10; 
  
        // Creating the CharBuffer 
        try { 
  
            // creating object of Intbuffer 
            // and allocating size capacity 
            CharBuffer cb = CharBuffer.allocate(capacity); 
  
            // putting the value in Intbuffer 
            cb.put('a'); 
            cb.put(2, 'b'); 
            cb.rewind(); 
  
            // checking CharBuffer cb is backed by array or not 
            boolean isArray = cb.hasArray(); 
  
            // checking if else condition 
            if (isArray) 
                System.out.println("CharBuffer cb is"
                                   + " backed by array"); 
            else
                System.out.println("CharBuffer cb is"
                                   + " not backed by any array"); 
        } 
  
        catch (IllegalArgumentException e) { 
            System.out.println("IllegalArgumentException catched"); 
        } 
  
        catch (ReadOnlyBufferException e) { 
            System.out.println("ReadOnlyBufferException catched"); 
        } 
    } 
}

输出：

CharBuffer cb is backed by array

范例2：当缓冲区不由数组支持时

// 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 CharBuffer 
        int capacity = 10; 
  
        // Creating the CharBuffer 
        try { 
  
            // creating object of CharBuffer 
            // and allocating size capacity 
            CharBuffer cb = CharBuffer.allocate(capacity); 
  
            // putting the value in CharBuffer 
            cb.put('a'); 
            cb.put(2, 'b'); 
            cb.rewind(); 
  
            // Creating a read-only copy of CharBuffer 
            // using asReadOnlyBuffer() method 
            CharBuffer cb1 = cb.asReadOnlyBuffer(); 
  
            // checking CharBuffer cb is backed by array or not 
            boolean isArray = cb1.hasArray(); 
  
            // checking if else condition 
            if (isArray) 
                System.out.println("CharBuffer cb is"
                                   + " backed by array"); 
            else
                System.out.println("CharBuffer cb is"
                                   + " not backed by any array"); 
        } 
  
        catch (IllegalArgumentException e) { 
            System.out.println("IllegalArgumentException catched"); 
        } 
  
        catch (ReadOnlyBufferException e) { 
            System.out.println("ReadOnlyBufferException catched"); 
        } 
    } 
}

输出：

CharBuffer cb is not backed by any array

相关用法

注：本文由纯净天空筛选整理自gopaldave大神的英文原创作品 CharBuffer hasArray() method in Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。