Java DoubleBuffer flip()方法及示例

java.nio.DoubleBuffer类 的 flip() 方法是用来翻转这个缓冲区的。通过翻转这个缓冲区，意味着缓冲区将被修剪到当前位置，然后位置将被改变为零。在这个过程中，如果缓冲区上有任何标记，那么这个标记将被自动丢弃。

语法

public final DoubleBuffer flip()

返回值： 该方法返回翻转的DoubleBuffer实例。

下面是说明flip()方法的例子。

例子 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

例子 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

参考资料: https://docs.oracle.com/javase/9/docs/api/java/nio/DoubleBuffer.html#flip-