Java中的缓冲区 reset() 方法及示例
Java.nio.Buffer 类的reset()方法用于将此缓冲区的位置重置为先前标记的位置。调用此方法既不会更改也不会丢弃标记的值。
句法:
public Buffer reset()
返回值:此方法返回此缓冲区。
以下是说明 reset() 方法的示例:
示例 1:
Java
// Java program to demonstrate
// reset() 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);
// Typecast ByteBuffer to buffer
Buffer buffer = (Buffer)bb;
// try to set the position at index 2
buffer.position(2);
// Set this buffer mark position
// using mark() method
buffer.mark();
// try to set the position at index 4
buffer.position(4);
// display position
System.out.println("position before reset: "
+ buffer.position());
// try to call reset() to restore
// to the position we marked
buffer.reset();
// display position
System.out.println("position after reset: "
+ buffer.position());
}
catch (InvalidMarkException e) {
System.out.println("new position is less than "
+ "the position we marked before ");
System.out.println("Exception throws: " + e);
}
}
}
Java
// Java program to demonstrate
// reset() 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);
// Typecast ByteBuffer to buffer
Buffer buffer = (Buffer)bb;
// try to set the position at index 2
buffer.position(2);
// Set this buffer mark position
// using mark() method
buffer.mark();
// try to set the position at index 4
buffer.position(1);
// display position
System.out.println("position before reset: "
+ buffer.position());
// try to call reset() to restore
// to the position we marked
buffer.reset();
// display position
System.out.println("position after reset: "
+ buffer.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: 2
示例 2:
Java
// Java program to demonstrate
// reset() 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);
// Typecast ByteBuffer to buffer
Buffer buffer = (Buffer)bb;
// try to set the position at index 2
buffer.position(2);
// Set this buffer mark position
// using mark() method
buffer.mark();
// try to set the position at index 4
buffer.position(1);
// display position
System.out.println("position before reset: "
+ buffer.position());
// try to call reset() to restore
// to the position we marked
buffer.reset();
// display position
System.out.println("position after reset: "
+ buffer.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: 1
new position is less than the position we marked before
Exception throws: java.nio.InvalidMarkException
参考: https://docs.oracle.com/javase/9/docs/api/ Java/nio/Buffer.html#reset–