Java CharBuffer asReadOnlyBuffer()用法及代码示例

java.nio.CharBuffer类的asReadOnlyBuffer()方法用于使用该缓冲区的内容创建一个新的只读char缓冲区。新缓冲区是此缓冲区的副本。因此，对该缓冲区内容所做的更改将在新缓冲区中可见。

由于新缓冲区是只读缓冲区，因此不允许对其内容进行任何修改。这两个缓冲区的位置，限制和标记值将是独立的。新缓冲区的容量，限制，位置和标记值将与此缓冲区相同。如果此缓冲区本身是只读的，则此方法的行为与重复方法完全相同。

用法:

public abstract CharBuffer asReadOnlyBuffer()

返回值：此方法返回新的只读char缓冲区，其内容与此缓冲区相同。

下面是说明asReadOnlyBuffer()方法的示例：

范例1：

// Java program to demonstrate 
// asReadOnlyBuffer() 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(); 
  
            // print the charBuffer 
            System.out.println("Original CharBuffer:  "
                               + Arrays.toString(cb.array())); 
  
            // Creating a read-only copy of CharBuffer 
            // using asReadOnlyBuffer() method 
            CharBuffer charBuffer = cb.asReadOnlyBuffer(); 
  
            // print the CharBuffer 
            System.out.print("\nReadOnlyBuffer CharBuffer: "); 
  
            while (charBuffer.hasRemaining()) 
                System.out.print(charBuffer.get() + ", "); 
        } 
  
        catch (IllegalArgumentException e) { 
            System.out.println("IllegalArgumentException catched"); 
        } 
  
        catch (ReadOnlyBufferException e) { 
            System.out.println("ReadOnlyBufferException catched"); 
        } 
    } 
}

输出：

Original CharBuffer:  [a,  , b,  ,  ,  ,  ,  ,  ,  ]

ReadOnlyBuffer CharBuffer: a,  , b,  ,  ,  ,  ,  ,  ,  ,

范例2：

// Java program to demonstrate 
// asReadOnlyBuffer() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) throws Exception 
    { 
  
        // Declaring the capacity of the cb 
        int capacity1 = 10; 
  
        // Declaring the capacity of the cb1 
        int capacity2 = 5; 
  
        // Creating the CharBuffer 
        try { 
  
            // 
            // cb 
            // 
            // creating object of charbuffer cb 
            // and allocating size capacity 
            CharBuffer cb = CharBuffer.allocate(capacity1); 
  
            // putting the value in cb 
            cb.put('a'); 
            cb.put(2, 'b'); 
            cb.rewind(); 
  
            // print the CharBuffer 
            System.out.println("CharBuffer cb: "
                               + Arrays.toString(cb.array())); 
  
            // 
            // cb1 
            // 
            // creating object of charbuffer cb1 
            // and allocating size capacity 
            CharBuffer cb1 = CharBuffer.allocate(capacity2); 
  
            // putting the value in cb1 
            cb1.put(1, 'c'); 
            cb1.put(2, 'd'); 
            cb1.rewind(); 
  
            // print the CharBuffer 
            System.out.println("\nCharBuffer cb1: "
                               + Arrays.toString(cb1.array())); 
  
            // Creating a read-only copy of CharBuffer 
            // using asReadOnlyBuffer() method 
            CharBuffer readOnlyCb = cb.asReadOnlyBuffer(); 
  
            // print the CharBuffer 
            System.out.print("\nReadOnlyBuffer CharBuffer: "); 
  
            while (readOnlyCb.hasRemaining()) 
                System.out.print(readOnlyCb.get() + ", "); 
  
            // try to change readOnlyCb 
            System.out.println("\n\nTrying to get the array"
                               + " from ReadOnlyCb for editing"); 
  
            char[] fbarr = readOnlyCb.array(); 
        } 
        catch (IllegalArgumentException e) { 
            System.out.println("IllegalArgumentException catched"); 
        } 
        catch (ReadOnlyBufferException e) { 
            System.out.println("Exception thrown: " + e); 
        } 
    } 
}

输出：

CharBuffer cb: [a,  , b,  ,  ,  ,  ,  ,  ,  ]

CharBuffer cb1: [ , c, d,  ,  ]

ReadOnlyBuffer CharBuffer: a,  , b,  ,  ,  ,  ,  ,  ,  , 

Trying to get the array from ReadOnlyCb for editing
Exception thrown: 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 asReadOnlyBuffer() 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。