Java FloatBuffer clear()用法及代碼示例

java.nio.FloatBuffer類的clear()方法用於清除此緩衝區。該方法將位置和限製分別設置為零和容量，並丟棄標記。如果需要對channel-read進行序列化或放置操作，則應調用此方法。這意味著，如果需要讀取緩衝區，則clear()方法使緩衝區準備就緒，並將位置設置為零。例如：

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

該方法實際上並不會擦除緩衝區中的數據，但其命名方式就好像是刪除該數據一樣，因為該方法最常用於可能需要刪除的情況。

用法:

public final FloatBuffer clear()

參數：該方法不帶任何參數。

返回值：從其中清除所有數據後，此方法將返回此FloatBuffer實例。

下麵是說明clear()方法的示例：

範例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); 
        } 
    } 
}

輸出：

position before reset:4
position after reset:0

範例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()); 
    } 
}

輸出：

position before clear:3
position after clear:0

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

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注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 FloatBuffer clear() methods in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。