Java 中的 AtomicReferenceArray compareAndSet()方法，带示例
原文:https://www . geeksforgeeks . org/atomicreferencearray-compareandset-method-in-Java-with-examples/
如果原子引用数组对象的索引 I 处的当前值等于预期值，则使用原子引用数组类的 compareAndSet() 方法自动将原子引用数组的索引 I 的值设置为新值。如果更新成功，此方法将返回 true。
语法:
public final boolean
compareAndSet(
int i, E expectedValue, E newValue)
参数:该方法接受:
- I performs the operation as the index of the atomic reference array,
- Expected value is the expected value,
- The new value is the new value to be set.
返回值:如果成功，则该方法返回真，否则返回假，表示实际值与期望值不相等。
下面的程序说明了 compareAndSet()方法:
程序 1:
// Java program to demonstrate
// compareAndSet() method
import java.util.concurrent.atomic.*;
public class GFG {
public static void main(String[] args)
{
// create an atomic reference object.
AtomicReferenceArray<Integer> ref
= new AtomicReferenceArray<Integer>(3);
// set some value
ref.set(0, 1234);
ref.set(1, 4322);
// apply compareAndSet()
boolean op1
= ref.compareAndSet(0, 5434, 8913);
boolean op2
= ref.compareAndSet(1, 3236, 6543);
// print
System.out.println("Operation at index 0: "
+ op1);
System.out.println("Operation at index 0: "
+ op2);
}
}
输出:
Operation at index 0: false
Operation at index 0: false
程序二:
// Java program to demonstrate
// compareAndSet() method
import java.util.concurrent.atomic.*;
public class GFG {
public static void main(String[] args)
{
// create an atomic reference object.
AtomicReferenceArray<String> ref
= new AtomicReferenceArray<String>(3);
// set some value
ref.set(0, "GFG");
ref.set(1, "JS");
// apply compareAndSet()
boolean op1
= ref.compareAndSet(
0, "GFG",
"GEEKS FOR GEEKS");
boolean op2
= ref.compareAndSet(
1, "JS",
"JAVA SCRIPT");
// print
System.out.println("Operation at index 0: "
+ op1);
System.out.println("New value at index 0: "
+ ref.get(0));
System.out.println("Operation at index 1: "
+ op2);
System.out.println("New value at index 1: "
+ ref.get(1));
}
}
输出:
Operation at index 0: true
New value at index 0: GEEKS FOR GEEKS
Operation at index 1: true
New value at index 1: JAVA SCRIPT
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