Java AtomicLongArray getAndAdd()用法及代碼示例

Java.util.concurrent.atomic.AtomicLongArray.getAndAdd()是Java中的一種內置方法，該方法原子地將給定值添加到AtomicLongArray索引處的元素。此方法將AtomicLongArray的索引值和要添加的值作為參數，並返回添加操作之前的值。函數getAndAdd()與addAndGet()類似，但前一個函數在加法運算之前返回值，而後一個函數在加法運算之後返回值。

用法:

public final long getAndAdd(int i, long delta)

參數：該函數接受兩個參數：

i–要在其中添加值的索引。
delta–要添加的值。

返回值：該函數返回加長操作之前的值，該值為long類型。

以下示例程序旨在說明上述方法：

示例1:

// Java program that demonstrates 
// the getAndAdd() function 
  
import java.util.concurrent.atomic.AtomicLongArray; 
  
public class GFG { 
    public static void main(String args[]) 
    { 
        // Initializing an array 
        long a[] = { 10, 22, 33, 44, 55 }; 
  
        // Initializing an AtomicLongArray with array a 
        AtomicLongArray arr = new AtomicLongArray(a); 
  
        // Displaying the AtomicLongArray 
        System.out.println("The array : " + arr); 
  
        // Index where value is to be added 
        int idx = 0; 
  
        // Value to add with value at idx 
        long x = 16; 
  
        // Updating the value at 
        // idx applying getAndAdd and 
        // storing the previous value 
        long prev = arr.getAndAdd(idx, x); 
  
        // Previous value at index idx 
        // before update 
        System.out.println("Value at index " + idx 
                           + " before update is " + prev); 
  
        // Displaying the AtomicLongArray 
        System.out.println("The array after update : "
                           + arr); 
    } 
}

輸出：

The array : [10, 22, 33, 44, 55]
Value at index 0 before update is 10
The array after update : [26, 22, 33, 44, 55]

示例2:

// Java program that demonstrates 
// the getAndAdd() function 
  
import java.util.concurrent.atomic.AtomicLongArray; 
  
public class GFG { 
    public static void main(String args[]) 
    { 
        // Initializing an array 
        long a[] = { 1, 2, 3, 4, 5 }; 
  
        // Initializing an AtomicLongArray with array a 
        AtomicLongArray arr = new AtomicLongArray(a); 
  
        // Displaying the AtomicLongArray 
        System.out.println("The array : " + arr); 
  
        // Index where value is to be added 
        int idx = 3; 
  
        // Value to add with value at idx 
        long x = 16; 
  
        // Updating the value at 
        // idx applying getAndAdd and 
        // storing the previous value 
        long prev = arr.getAndAdd(idx, x); 
  
        // Previous value at index idx 
        // before update 
        System.out.println("Value at index " + idx 
                           + " before update is "
                           + prev); 
  
        // Displaying the AtomicLongArray 
        System.out.println("The array after update : "
                           + arr); 
    } 
}

輸出：

The array : [1, 2, 3, 4, 5]
Value at index 3 before update is 4
The array after update : [1, 2, 3, 20, 5]

參考：
https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/AtomicLongArray.html#getAndAdd-int-long-

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注：本文由純淨天空篩選整理自rupesh_rao大神的英文原創作品 AtomicLongArray getAndAdd() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。