Java Buffer isReadOnly()用法及代碼示例

java.nio.Buffer類的isReadOnly()方法用於判斷此緩衝區是否為隻讀。

用法:

public abstract boolean isReadOnly()

返回值：僅當此緩衝區是隻讀的時，此方法將返回true。

下麵是說明isReadOnly()方法的示例：

範例1：

// Java program to demonstrate 
// isReadOnly() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 10; 
  
        // creating object of bytebuffer 
        // and allocating size capacity 
        ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
        // putting the value in bytebuffer 
        bb.put((byte)10); 
        bb.put((byte)20); 
        bb.rewind(); 
  
        // Typecast bytebuffer to Buffer 
        Buffer buffer = (Buffer)bb; 
  
        // checking buffer is backed by array or not 
        boolean isReadOnly = buffer.isReadOnly(); 
  
        // checking if else condition 
        if (isReadOnly) 
            System.out.println("buffer is"
                               + " ReadOnly buffer"); 
        else
            System.out.println("buffer is not"
                               + " ReadOnly buffer"); 
    } 
}

輸出：

buffer is not ReadOnly buffer

範例2：

// Java program to demonstrate 
// isReadOnly() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 10; 
  
        // creating object of bytebuffer 
        // and allocating size capacity 
        ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
        // putting the value in bytebuffer 
        bb.put((byte)10); 
        bb.put((byte)20); 
        bb.rewind(); 
  
        // Creating a read-only copy of ByteBuffer 
        // using asReadOnlyBuffer() method 
        ByteBuffer bb1 = bb.asReadOnlyBuffer(); 
  
        // Typecast read-only ByteBuffer to read-only buffer 
        Buffer buffer = (Buffer)bb1; 
  
        // checking buffer is backed by array or not 
        boolean isReadOnly = buffer.isReadOnly(); 
  
        // checking if else condition 
        if (isReadOnly) 
            System.out.println("buffer is"
                               + " ReadOnly buffer"); 
        else
            System.out.println("buffer is not"
                               + " ReadOnly buffer"); 
    } 
}

輸出：

buffer is ReadOnly buffer

參考： https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.html#isReadOnly-

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注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 Buffer isReadOnly() methods in Java with Examples。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。