Java中的 DoubleBuffer flip() 方法及示例

Java.nio.DoubleBuffer 类的flip()方法用于翻转这个缓冲区。通过翻转这个缓冲区，这意味着缓冲区将被修剪到当前位置，然后该位置将变为零。在此过程中，如果缓冲区上有任何标记，则该标记将被自动丢弃。

句法：

public final DoubleBuffer flip()

返回值：该方法返回翻转后的 DoubleBuffer 实例。

以下是说明翻转（）方法的示例：

示例 1：

// Java program to demonstrate
// flip() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Declare and initialize
        // the double array
        double[] db
            = { 10.56, 20.34, 30.78 };
  
        // wrap the double array
        // into DoubleBuffer
        // using wrap() method
        DoubleBuffer doubleBuffer
            = DoubleBuffer.wrap(db);
  
        // set position at index 1
        doubleBuffer.position(1);
  
        // print the buffer
        System.out.println(
            "Buffer before flip: "
            + Arrays.toString(
                  doubleBuffer.array())
            + "\nPosition: "
            + doubleBuffer.position()
            + "\nLimit: "
            + doubleBuffer.limit());
  
        // Flip the Buffer
        // using flip() method
        doubleBuffer.flip();
  
        // print the buffer
        System.out.println(
            "\nBuffer after flip: "
            + Arrays.toString(
                  doubleBuffer.array())
            + "\nPosition: "
            + doubleBuffer.position()
            + "\nLimit: "
            + doubleBuffer.limit());
    }
}

输出：

Buffer before flip: [10.56, 20.34, 30.78]
Position: 1
Limit: 3

Buffer after flip: [10.56, 20.34, 30.78]
Position: 0
Limit: 1

示例 2：

// Java program to demonstrate
// flip() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // defining and allocating DoubleBuffer
        // using allocate() method
        DoubleBuffer doubleBuffer
            = DoubleBuffer.allocate(4);
  
        // put double value in DoubleBuffer
        // using put() method
        doubleBuffer.put(20.4);
        doubleBuffer.put(34.5);
  
        // set position at index 1
        doubleBuffer.position(1);
  
        // print the buffer
        System.out.println(
            "Buffer before flip: "
            + Arrays.toString(
                  doubleBuffer.array())
            + "\nPosition: "
            + doubleBuffer.position()
            + "\nLimit: "
            + doubleBuffer.limit());
  
        // Flip the Buffer
        // using flip() method
        doubleBuffer.flip();
  
        // print the buffer
        System.out.println(
            "\nBuffer after flip: "
            + Arrays.toString(
                  doubleBuffer.array())
            + "\nPosition: "
            + doubleBuffer.position()
            + "\nLimit: "
            + doubleBuffer.limit());
    }
}

输出：

Buffer before flip: [20.4, 34.5, 0.0, 0.0]
Position: 1
Limit: 4

Buffer after flip: [20.4, 34.5, 0.0, 0.0]
Position: 0
Limit: 1

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