Java中的 AtomicLongArray getAndIncrement() 方法及示例

Java.util.concurrent.atomic.AtomicLongArray.getAndIncrement()是Java中的一种内置方法，它以原子方式将 AtomicLongArray 的任何索引处的值加一。该方法将 AtomicLongArray 的索引值作为参数，返回递增前该索引处的值，然后递增该索引处的值。 getAndIncrement()函数与incrementAndGet()函数类似，但前者返回增量前的值，后者返回增量操作后的值。

句法：

public final long getAndIncrement(int i)

参数：该函数接受一个参数i ，它是执行递增一次操作的索引。

返回值：该函数返回更新前该索引处的前一个值，该值位于long中。

下面的程序说明了上述方法：

方案一：

// Java program that demonstrates
// the getAndIncrement() function
  
import java.util.concurrent.atomic.AtomicLongArray;
  
public class GFG {
    public static void main(String args[])
    {
        // Initializing an array
        long a[] = { 11, 12, 13, 14, 15 };
  
        // Initializing an AtomicLongArray with array a
        AtomicLongArray arr = new AtomicLongArray(a);
  
        // Displaying the AtomicLongArray
        System.out.println("The array : " + arr);
  
        // Index where operation is performed
        int idx = 0;
  
        // Updating the value at
        // idx applying getAndIncrement
        // and storing the previous value
        long prev = arr.getAndIncrement(idx);
  
        // Previous value at idx before update
        System.out.println("Value at index " + idx
                           + " before the update is "
                           + prev);
  
        // Displaying the AtomicLongArray
        System.out.println("The array after update : "
                           + arr);
    }
}

输出：

The array : [11, 12, 13, 14, 15]
Value at index 0 before the update is 11
The array after update : [12, 12, 13, 14, 15]

方案二：

// Java program that demonstrates
// the getAndIncrement() function
  
import java.util.concurrent.atomic.AtomicLongArray;
  
public class GFG {
    public static void main(String args[])
    {
        // Initializing an array
        long a[] = { 11, 12, 13, 14, 15 };
  
        // Initializing an AtomicLongArray with array a
        AtomicLongArray arr = new AtomicLongArray(a);
  
        // Displaying the AtomicLongArray
        System.out.println("The array : " + arr);
  
        // Index where operation is performed
        int idx = 3;
  
        // Updating the value at
        // idx applying getAndIncrement
        // and storing the previous value
        long prev = arr.getAndIncrement(idx);
  
        // Previous value at idx before update
        System.out.println("Value at index " + idx
                           + " before the update is "
                           + prev);
  
        // Displaying the AtomicLongArray
        System.out.println("The array after update : "
                           + arr);
    }
}

输出：

The array : [11, 12, 13, 14, 15]
Value at index 3 before the update is 14
The array after update : [11, 12, 13, 15, 15]

注意： getAndIncrement()函数与 incrementAndGet()函数类似，但后者返回更新后的值，而前者返回更新后的先前值。

参考： https: Java/util/concurrent/atomic/AtomicLongArray.html#getAndIncrement-int-