Java 中的 DoubleBuffer 标记()方法，示例
原文:https://www . geesforgeks . org/double buffer-mark-methods-in-Java-with-examples/
java.nio.DoubleBuffer 类的标记()方法用来标记这个 DoubleBuffer 的当前位置作为这个缓冲区的标记。
语法:
public DoubleBuffer mark()
返回值:在当前位置设置缓冲区标记后，该方法返回该双缓冲区。
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 {
double[] darr = { 10.5, 20.5, 30.5, 40.5 };
// creating object of DoubleBuffer
// and allocating size capacity
DoubleBuffer db = DoubleBuffer.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 4
db.position(4);
// 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("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 {
double[] darr = { 10.5, 20.5, 30.5, 40.5 };
// creating object of DoubleBuffer
// and allocating size capacity
DoubleBuffer db = DoubleBuffer.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/double buffer . html # mark–
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