Java中的 LongBuffer flip() 方法及示例

Java.nio.LongBuffer 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
• 然后位置将更改为零
• 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 LongBuffer flip()

参数：此方法不接受任何参数。

返回值：该方法返回翻转后的LongBuffer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 long array
        long[] db
            = { 10, 20, 30 };
  
        // wrap the long array
        // into LongBuffer
        // using wrap() method
        LongBuffer longBuffer
            = LongBuffer.wrap(db);
  
        // set position at index 1
        longBuffer.position(1);
  
        // print the buffer
        System.out.println(
            "Buffer before flip: "
            + Arrays.toString(
                  longBuffer.array())
            + "\nPosition: "
            + longBuffer.position()
            + "\nLimit: "
            + longBuffer.limit());
  
        // Flip the Buffer
        // using flip() method
        longBuffer.flip();
  
        // print the buffer
        System.out.println(
            "\nBuffer after flip: "
            + Arrays.toString(
                  longBuffer.array())
            + "\nPosition: "
            + longBuffer.position()
            + "\nLimit: "
            + longBuffer.limit());
    }
}

输出：

Buffer before flip: [10, 20, 30]
Position: 1
Limit: 3

Buffer after flip: [10, 20, 30]
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 LongBuffer
        // using allocate() method
        LongBuffer longBuffer
            = LongBuffer.allocate(4);
  
        // put long value in LongBuffer
        // using put() method
        longBuffer.put(20);
        longBuffer.put(34);
  
        // set position at index 1
        longBuffer.position(1);
  
        // print the buffer
        System.out.println(
            "Buffer before flip: "
            + Arrays.toString(
                  longBuffer.array())
            + "\nPosition: "
            + longBuffer.position()
            + "\nLimit: "
            + longBuffer.limit());
  
        // Flip the Buffer
        // using flip() method
        longBuffer.flip();
  
        // print the buffer
        System.out.println(
            "\nBuffer after flip: "
            + Arrays.toString(
                  longBuffer.array())
            + "\nPosition: "
            + longBuffer.position()
            + "\nLimit: "
            + longBuffer.limit());
    }
}

输出：

Buffer before flip: [20, 34, 0, 0]
Position: 1
Limit: 4

Buffer after flip: [20, 34, 0, 0]
Position: 0
Limit: 1

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