Java 中的 AtomicLong compareAndSet()方法，带示例
原文:https://www . geesforgeks . org/atomiclong-compareandset-method-in-Java-with-examples/
Java . util . concurrent . atomic . atomic clong . compareandset()是 Java 中的一个内置方法，如果当前值等于也在参数中传递的预期值，则将该值设置为参数中传递的值。该函数返回一个布尔值，它告诉我们更新是否完成。
语法:
public final boolean compareAndSet(long expect,
long val)
参数:函数接受两个强制参数，描述如下:
- Expected: Specifies the value that the atomic object should be.
- Val: Specifies that the atomic integer is equal to the expected value to be updated.
返回值:函数返回一个布尔值，成功则返回真，否则返回假。
下面的程序说明了上述方法:
程序 1:
// Java program that demonstrates
// the compareAndSet() function
import java.util.concurrent.atomic.AtomicLong;
public class GFG {
public static void main(String args[])
{
// Initially value as 0
AtomicLong val = new AtomicLong(0);
// Prints the updated value
System.out.println("Previous value: "
+ val);
// Checks if previous value was 0
// and then updates it
boolean res = val.compareAndSet(0, 6);
// Checks if the value was updated.
if (res)
System.out.println("The value was "
+ "updated and it is "
+ val);
else
System.out.println("The value was "
+ "not updated");
}
}
输出:
Previous value: 0
The value was updated and it is 6
程序二:
// Java program that demonstrates
// the compareAndSet() function
import java.util.concurrent.atomic.AtomicLong;
public class GFG {
public static void main(String args[])
{
// Initially value as 0
AtomicLong val = new AtomicLong(0);
// Prints the updated value
System.out.println("Previous value: "
+ val);
// Checks if previous value was 0
// and then updates it
boolean res = val.compareAndSet(10, 6);
// Checks if the value was updated.
if (res)
System.out.println("The value was "
+ "updated and it is "
+ val);
else
System.out.println("The value was "
+ "not updated");
}
}
输出:
Previous value: 0
The value was not updated
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