Java IntBuffer mark()方法及实例

java.nio.IntBuffer类的 mark() 方法是用来标记这个IntBuffer的当前位置作为这个缓冲区的标记。

语法

public final IntBuffer mark()

参数： 本方法不接受任何参数。

返回值： 该方法在设置了缓冲区在当前位置的标记后返回该IntBuffer。

下面是说明mark()方法的例子。

例子 1 :

// Java program to demonstrate// mark() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          try {              int[] farr = { 10, 20, 30, 40 };              // creating object of IntBuffer            // and allocating size capacity            IntBuffer ib = IntBuffer.wrap(farr);              // try to set the position at index 2            ib.position(2);              // Set this buffer mark position            // using mark() method            ib.mark();              // try to set the position at index 4            ib.position(4);              // display position            System.out.println("position before reset: "                               + ib.position());              // try to call reset() to restore            // to the position we marked            ib.reset();              // display position            System.out.println("position after reset: "                               + ib.position());        }          catch (InvalidMarkException e) {            System.out.println("New position "                               + "is less than "                               + "the position "                               + "marked before ");            System.out.println("Exception throws: "                               + e);        }    }}

输出:

position before reset: 4position after reset: 2

实例2： 演示InvalidMarkException

// Java program to demonstrate// mark() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          try {              int[] farr = { 10, 20, 30, 40 };              // creating object of IntBuffer            // and allocating size capacity            IntBuffer ib = IntBuffer.wrap(farr);              // try to set the position at index 2            ib.position(2);              // Set this buffer mark position            // using mark() method            ib.mark();              // try to set the position at index 1            ib.position(1);              // display position            System.out.println("position before reset: "                               + ib.position());              // try to call reset() to restore            // to the position we marked            ib.reset();              // display position            System.out.println("position after reset: "                               + ib.position());        }          catch (InvalidMarkException e) {            System.out.println("\nNew position "                               + "is less than "                               + "the position "                               + "marked before ");            System.out.println("Exception throws: "                               + e);        }    }}

输出:

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

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