Java CharBuffer arrayOffset()用法及代码示例

java.nio.CharBuffer类的arrayOffset()方法用于返回缓冲区第一个元素的缓冲区支持数组内的偏移量。这意味着，如果此缓冲区由数组支持，则缓冲区位置p对应于数组索引p + arrayOffset()。

为了检查此缓冲区是否具有后备数组，可以使用hasArray()方法。它确保此缓冲区具有可访问的后备数组。

用法:

public final int arrayOffset()

返回值：此方法返回此缓冲区数组中第一个元素的偏移量。

异常：如果此缓冲区由数组支持，但此方法是只读的，则此方法将引发ReadOnlyBufferException

以下示例程序旨在说明arrayOffset()方法。

示例1:

// Java program to demonstrate 
// arrayOffset() 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'); 
  
            // print the CharBuffer 
            System.out.println("CharBuffer: "
                               + Arrays.toString(cb.array())); 
  
            // print the arrayOffset 
            System.out.println("arrayOffset: "
                               + cb.arrayOffset()); 
        } 
  
        catch (IllegalArgumentException e) { 
            System.out.println("IllegalArgumentException catched"); 
        } 
  
        catch (ReadOnlyBufferException e) { 
            System.out.println("Exception throws" + e); 
        } 
    } 
}

输出：

CharBuffer: [a, , b, , , , , , , ]
arrayOffset: 0

示例2:演示ReadOnlyBufferException

// Java program to demonstrate 
// arrayOffset() 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 fb = CharBuffer.allocate(capacity); 
  
            // putting the value in CharBuffer 
            fb.put('a'); 
            fb.put(2, 'b'); 
            fb.rewind(); 
  
            // Creating a read-only copy of CharBuffer 
            // using asReadOnlyBuffer() method 
            CharBuffer cb1 = fb.asReadOnlyBuffer(); 
  
            // print the CharBuffer 
            System.out.print("Read only buffer : "); 
            while (cb1.hasRemaining()) 
                System.out.print(cb1.get() + ", "); 
  
            // next line 
            System.out.println(""); 
  
            // print the arrayOffset 
            System.out.println("\nTry to print the array offset"
                               + " of read only buffer"); 
            System.out.println("arrayOffset: " + cb1.arrayOffset()); 
        } 
  
        catch (IllegalArgumentException e) { 
            System.out.println("Exception throws: " + e); 
        } 
  
        catch (ReadOnlyBufferException e) { 
            System.out.println("Exception throws: " + e); 
        } 
    } 
}

输出：

Read only buffer : a, , b, , , , , , , , 

Try to print the array offset of read only buffer
Exception throws: java.nio.ReadOnlyBufferException

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 arrayOffset() 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。