用示例标记 Java 中的 ByteBuffer()方法
原文:https://www . geeksforgeeks . org/bytebuffer-mark-methods-in-Java-with-examples/
java.nio.ByteBuffer 类的标记()方法用于将该缓冲区的标记设置在其位置。
语法:
public ByteBuffer mark()
返回值:这个方法返回这个缓冲区。
下面是说明 mark()方法的示例:
示例 1:
// Java program to demonstrate
// mark() 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);
// try to set the position at index 2
bb.position(2);
// Set this buffer mark position
// using mark() method
bb.mark();
// try to set the position at index 4
bb.position(4);
// display position
System.out.println("position before reset: "
+ bb.position());
// try to call reset() to restore
// to the position we marked
bb.reset();
// display position
System.out.println("position after reset: "
+ bb.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: 演示无效标记异常
// Java program to demonstrate
// mark() 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);
// try to set the position at index 2
bb.position(2);
// Set this buffer mark position
// using mark() method
bb.mark();
// try to set the position at index 4
bb.position(1);
// display position
System.out.println("position before reset: "
+ bb.position());
// try to call reset() to restore
// to the position we marked
bb.reset();
// display position
System.out.println("position after reset: "
+ bb.position());
}
catch (InvalidMarkException e) {
System.out.println("\nnew 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/bytebuffer . html # mark–
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