Java 中的 LongBuffer mark()方法，带示例
原文:https://www . geesforgeks . org/longbuffer-mark-method-in-Java-with-examples/
java.nio.LongBuffer 类的标记()方法用来标记这个 LongBuffer 的当前位置作为这个缓冲区的标记。
语法:
public LongBuffer mark()
参数:此方法不接受任何参数。
返回值:此方法在当前位置设置好缓冲区的标记后，返回此长补刀。
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 {
long[] darr = { 10, 20, 30, 40 };
// creating object of LongBuffer
// and allocating size capacity
LongBuffer lb = LongBuffer.wrap(darr);
// try to set the position at index 2
lb.position(2);
// Set this buffer mark position
// using mark() method
lb.mark();
// try to set the position at index 4
lb.position(4);
// display position
System.out.println("position before reset: "
+ lb.position());
// try to call reset() to restore
// to the position we marked
lb.reset();
// display position
System.out.println("position after reset: "
+ lb.position());
}
catch (InvalidMarkException e) {
System.out.println("New position "
+ "is less than "
+ "the position "
+ "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 {
long[] darr = { 10, 20, 30, 40 };
// creating object of LongBuffer
// and allocating size capacity
LongBuffer db = LongBuffer.wrap(darr);
// try to set the position at index 2
db.position(2);
// Set this buffer mark position
// using mark() method
db.mark();
// try to set the position at index 1
db.position(1);
// display position
System.out.println("position before reset: "
+ db.position());
// try to call reset() to restore
// to the position we marked
db.reset();
// display position
System.out.println("position after reset: "
+ db.position());
}
catch (InvalidMarkException e) {
System.out.println("\nNew position "
+ "is less than "
+ "the position "
+ "marked before ");
System.out.println("Exception throws: "
+ e);
}
}
}
输出:
position before reset: 1
New position is less than the position marked before
Exception throws: java.nio.InvalidMarkException
参考:https://docs . Oracle . com/javase/9/docs/API/Java/nio/longbuffer . html # mark–
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