Java Buffer isReadOnly()方法及示例

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Java Buffer isReadOnly()方法及示例

java.nio.Buffer 类的 isReadOnly() 方法是用来告诉这个缓冲区是否是只读的。

语法

public abstract boolean isReadOnly()

返回： 该方法将在且仅在该缓冲区为只读时返回true。

下面是说明 isReadOnly() 方法的例子。

例子 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");    }}

输出:

buffer is not ReadOnly buffer

例子 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");    }}

输出: