Java CharBuffer arrayOffset()用法及代碼示例

java.nio.CharBuffer類的arrayOffset()方法用於返回緩衝區第一個元素的緩衝區支持數組內的偏移量。這意味著，如果此緩衝區由數組支持，則緩衝區位置p對應於數組索引p + arrayOffset()。

為了檢查此緩衝區是否具有後備數組，可以使用hasArray()方法。它確保此緩衝區具有可訪問的後備數組。

用法:

public final int arrayOffset()

返回值：此方法返回此緩衝區數組中第一個元素的偏移量。

異常：如果此緩衝區由數組支持，但此方法是隻讀的，則此方法將引發ReadOnlyBufferException

以下示例程序旨在說明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); 
        } 
    } 
}

輸出：

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); 
        } 
    } 
}

輸出：

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

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

相關用法

注：本文由純淨天空篩選整理自gopaldave大神的英文原創作品 CharBuffer arrayOffset() method in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。