Java DoubleBuffer reset()方法及示例

java.nio.DoubleBuffer类的 reset() 方法是用来将这个缓冲区的位置重置到之前标记的位置。在这个过程中，既不改变也不丢弃被标记的值。它有助于恢复缓冲区中先前标记的值。

语法

public final DoubleBuffer reset()

参数： 该方法不接受任何参数。

返回值： 该方法返回这个缓冲区。

下面是说明reset()方法的例子。

例子 1 :

// Java program to demonstrate// reset() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          try {              double[] darr = { 10.5, 20.5, 30.5, 40.5 };              // creating object of DoubleBuffer            // and allocating size capacity            DoubleBuffer db = DoubleBuffer.wrap(darr);              // try to set the position at index 2            db.position(2);              // Set this buffer mark position            // using mark() method            db.mark();              // try to set the position at index 4            db.position(4);              // display position            System.out.println("position before reset: "                               + db.position());              // try to call reset() to restore            // to the position we marked            db.reset();              // display position            System.out.println("position after reset: "                               + db.position());        }          catch (InvalidMarkException e) {            System.out.println("new position is less than "                               + "the position we"                               + " marked before ");            System.out.println("Exception throws: " + e);        }    }}

输出:

position before reset: 4position after reset: 2

例子 2 :

// Java program to demonstrate// reset() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          try {              double[] darr = { 10.5, 20.5, 30.5, 40.5 };              // creating object of DoubleBuffer            // and allocating size capacity            DoubleBuffer db = DoubleBuffer.wrap(darr);              // try to set the position at index 2            db.position(2);              // Set this buffer mark position            // using mark() method            db.mark();              // try to set the position at index 4            db.position(1);              // display position            System.out.println("position before reset: "                               + db.position());              // try to call reset() to restore            // to the position we marked            db.reset();              // display position            System.out.println("position after reset: "                               + db.position());        }          catch (InvalidMarkException e) {            System.out.println("\nnew position is less than "                               + "the position we"                               + " marked before ");            System.out.println("Exception throws: " + e);        }    }}

输出:

position before reset: 1new position is less than the position we marked before Exception throws: java.nio.InvalidMarkException

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