Java FloatBuffer clear()用法及代码示例

java.nio.FloatBuffer类的clear()方法用于清除此缓冲区。该方法将位置和限制分别设置为零和容量，并丢弃标记。如果需要对channel-read进行序列化或放置操作，则应调用此方法。这意味着，如果需要读取缓冲区，则clear()方法使缓冲区准备就绪，并将位置设置为零。例如：

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

该方法实际上并不会擦除缓冲区中的数据，但其命名方式就好像是删除该数据一样，因为该方法最常用于可能需要删除的情况。

用法:

public final FloatBuffer clear()

参数：该方法不带任何参数。

返回值：从其中清除所有数据后，此方法将返回此FloatBuffer实例。

下面是说明clear()方法的示例：

范例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:4
position after reset:0

范例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:3
position after clear:0

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

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注：本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 FloatBuffer clear() methods in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。