Java AtomicLongArray getAndSet()用法及代码示例

Java.util.concurrent.atomic.AtomicLongArray.getAndSet()是Java中的内置方法，该方法原子地在AtomicLongArray的任何给定位置设置给定值。该方法采用AtomicLongArray的索引值和要设置为参数的值。在给定索引处设置新值之前，它将返回给定索引处的值。函数getAndSet()与set()函数相似，但前者返回值，而后者不返回任何值。
用法:

public final long getAndSet(int i, long newValue)

参数：该函数接受两个参数：

i–要进行更新的索引。
newValue–在索引i处设置的值

返回值：函数将在很长的更新之前返回给定索引处的值。

以下示例程序旨在说明上述方法：

示例1:

// Java program that demonstrates 
// the getAndSet() 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; 
  
        // New value to set at idx 
        long val = 100; 
  
        // Updating the value at 
        // idx applying getAndSet 
        // and store previous value 
        long prev = arr.getAndSet(idx, val); 
  
        // 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 : [100, 12, 13, 14, 15]

示例2:

// Java program that demonstrates 
// the getAndSet() 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; 
  
        // New value to set at idx 
        long val = 10; 
  
        // Updating the value at 
        // idx applying getAndSet 
        // and store previous value 
        long prev = arr.getAndSet(idx, val); 
  
        // 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, 10, 15]

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

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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 getAndSet() 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。