Java AtomicLongArray getAndIncrement()用法及代码示例

Java.util.concurrent.atomic.AtomicLongArray.getAndIncrement()是Java中的一种内置方法，可以自动将AtomicLongArray的任何索引上存在的值加1。该方法将AtomicLongArray的索引值作为参数，在递增之前返回该索引处的值，然后在该索引处递增该值。函数getAndIncrement()与incrementAndGet()函数相似，但前者返回增量前的值，而后者返回增量操作后的值。

用法:

public final long getAndIncrement(int i)

参数：该函数接受单个参数i，该参数是执行一个操作递增的索引。

返回值：函数将在很长的更新之前返回该索引处的先前值。

以下示例程序旨在说明上述方法：

示例1:

// 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]

示例2:

// 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：函数getAndIncrement()与incrementAndGet()类似，但后一个函数返回更新后的值，而前一个函数在更新后返回前一个值。

参考：https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/AtomicLongArray.html#getAndIncrement-int-

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注：本文由纯净天空筛选整理自rupesh_rao大神的英文原创作品 AtomicLongArray getAndIncrement() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。