Java中的 AtomicBoolean compareAndSet() 方法及示例
Java.util.concurrent.atomic.AtomicBoolean.compareAndSet()是Java中的一个内置方法,如果当前值等于参数中传递的预期值,则该方法将值设置为参数中传递的值。该函数返回一个布尔值,它让我们知道更新是否完成。
句法:
public final boolean compareAndSet(boolean expect, boolean val)
参数:该函数接受两个强制性参数,如下所述:
- 期望:它指定原子对象应该是的值。
- val:如果原子布尔值等于期望值,则指定要更新的值。
返回值:函数返回一个布尔值,成功则返回true,否则返回false。
下面的程序说明了上述函数:
方案一:
// Java Program to demonstrates
// the compareAndSet() function
import java.util.concurrent.atomic.AtomicBoolean;
public class GFG {
public static void main(String args[])
{
// Initially value as false
AtomicBoolean val = new AtomicBoolean(false);
// Prints the updated value
System.out.println("Previous value: "
+ val);
// Checks if previous value was false
// and then updates it
boolean res = val.compareAndSet(false, true);
// 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: false
The value was updated and it is true
方案二:
// Java Program to demonstrates
// the compareAndSet() function
import java.util.concurrent.atomic.AtomicBoolean;
public class GFG {
public static void main(String args[])
{
// Initially value as true
AtomicBoolean val = new AtomicBoolean(true);
// Prints the updated value
System.out.println("Previous value: "
+ val);
// Checks if previous value was true
// and then updates it
boolean res = val.compareAndSet(true, false);
// 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: true
The value was updated and it is false
参考: https: Java/util/concurrent/atomic/AtomicBoolean.html#compareAndSet(boolean, %20boolean)