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: 1Limit: 3Buffer after flip: [10.56, 20.34, 30.78]Position: 0Limit: 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: 1Limit: 4Buffer after flip: [20.4, 34.5, 0.0, 0.0]Position: 0Limit: 1

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