Java FloatBuffer clear()方法及示例

java.nio.FloatBuffer 类的 clear() 方法是用来清除这个缓冲区。这个方法将位置和极限分别设置为零和容量，并丢弃标记。当有任何必要进行通道读或放操作的序列时，应该调用这个方法。这意味着如果缓冲区需要被读取，那么clear()方法将使缓冲区准备好并将位置设置为零。比如说。

buf.clear();     // Prepare buffer for readingin.read(buf);    // Read data

该方法实际上并没有删除缓冲区中的数据，但它被命名为好像删除了一样，因为它最经常被用于删除的情况。

语法

public final FloatBuffer clear()

参数： 该方法不接受任何参数。

返回值： 该方法在清除FloatBuffer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1 :

// Java program to demonstrate// clear() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          try {              float[] farr = { 2.5f, 3.5f, 4.5f, 6.7f };              // creating object of FloatBuffer            // and allocating size capacity            FloatBuffer fb                = FloatBuffer.wrap(farr);              // try to set the position at index 2            fb.position(2);              // Set this buffer mark position            // using mark() method            fb.mark();              // try to set the position at index 4            fb.position(4);              // display position            System.out.println("position before reset: "                               + fb.position());              // try to call clear() to restore            // to the position at index 0            // by discarding the mark            fb.clear();              // display position            System.out.println("position after reset: "                               + fb.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2 :

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

输出。

position before clear: 3position after clear: 0

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