java.nio.ByteBuffer类的clear()方法用于清除此缓冲区。位置设置为零,限制设置为容量,并且标记被丢弃。在使用序列channel-read之前,请调用此方法,或者进行操作以填充此缓冲区。
例如:
buf.clear(); // Prepare buffer for reading in.read(buf); // Read data
该方法实际上并没有擦除缓冲区中的数据,但它的命名方式就好像它确实如此,因为该方法最常用于可能是这种情况的情况。
用法:
public Buffer clear()
返回值:此方法返回此缓冲区。
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 {
byte[] barr = { 10, 20, 30, 40 };
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.wrap(barr);
// Typecasting ByteBuffer into Buffer
Buffer bb1 = (Buffer)bb;
// try to set the position at index 2
bb1.position(2);
// Set this buffer mark position
// using mark() method
bb1.mark();
// try to set the position at index 4
bb1.position(4);
// display position
System.out.println("position before reset:"
+ bb1.position());
// try to call clear() to restore
// to the position at index 0
// by discarding the mark
bb1.clear();
// display position
System.out.println("position after reset:"
+ bb1.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)
{
try {
byte[] barr = { 10, 20, 30, 40 };
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.wrap(barr);
// Typecasting ByteBuffer into Buffer
Buffer bb1 = (Buffer)bb;
// try to set the position at index 2
bb1.position(3);
// display position
System.out.println("position before clear:"
+ bb1.position());
// try to call clear() to restore
// to the position at index 0
// by discarding the mark
bb1.clear();
// display position
System.out.println("position after clear:"
+ bb1.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 clear:3 position after clear:0
参考: https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.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 Buffer 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。