Java中的缓冲区 isDirect() 方法及示例

Java.nio.Buffer 类的isDirect()方法用于判断这个缓冲区是否是直接的。

句法：

public abstract boolean isDirect()

返回值：当且仅当此缓冲区是直接的时，此方法才返回 true。

下面是说明isDirect()方法的示例：

示例 1：

// Java program to demonstrate
// isDirect() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
        // defining and allocating ByteBuffer
        // using allocate() method
        ByteBuffer byteBuffer
            = ByteBuffer.allocateDirect(4);
  
        // Typecast byteBuffer to buffer
        Buffer buffer = (Buffer)byteBuffer;
  
        // check the Buffer
        // using isDirect() method
        boolean val = buffer.isDirect();
  
        // checking the condition
        if (val)
            System.out.println("buffer is direct");
        else
            System.out.println("buffer is not direct");
    }
}

输出：

buffer is direct

示例 2：

// Java program to demonstrate
// isDirect() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
        // defining and allocating ByteBuffer
        // using allocate() method
        ByteBuffer byteBuffer = ByteBuffer.allocate(4);
  
        // Typecast byteBuffer to buffer
        Buffer buffer = (Buffer)byteBuffer;
  
        // check the byteBuffer
        // using isDirect() method
        boolean val = buffer.isDirect();
  
        // checking the condition
        if (val)
            System.out.println("buffer is direct");
        else
            System.out.println("buffer is not direct");
    }
}

输出：

buffer is not direct

参考： https://docs.oracle.com/javase/9/docs/api/ Java/nio/Buffer.html#isDirect–