Java DoubleBuffer clear()方法及示例

java.nio.CharBuffer 类的 clear() 方法被用来清除这个缓冲区。在清除这个缓冲区时，会做以下改变。

语法

public final DoubleBuffer clear()

返回值： 该方法在清除DoubleBuffer中的所有数据后返回该实例。

下面的例子说明了clear()方法的作用。

例子 1 :

// Java program to demonstrate// clear() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          try {              double[] darr = { 2.5, 3.5, 4.5, 6.7 };              // 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 clear() to restore            // to the position at index 0            // by discarding the mark            db.clear();              // 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: 0

例子 2 :

// Java program to demonstrate// clear() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          double[] carr = { 2.4, 105.4, 13.9, 23.45d };          // creating object of DoubleBuffer        // and allocating size capacity        DoubleBuffer db = DoubleBuffer.wrap(carr);          // try to set the position at index 3        db.position(3);          // display position        System.out.println("position before clear: "                           + db.position());          // try to call clear() to restore        // to the position at index 0        // by discarding the mark        db.clear();          // display position        System.out.println("position after clear: "                           + db.position());    }}

输出:

position before clear: 3position after clear: 0

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