Java AtomicLongArray getAndSet()用法及代碼示例

Java.util.concurrent.atomic.AtomicLongArray.getAndSet()是Java中的內置方法，該方法原子地在AtomicLongArray的任何給定位置設置給定值。該方法采用AtomicLongArray的索引值和要設置為參數的值。在給定索引處設置新值之前，它將返回給定索引處的值。函數getAndSet()與set()函數相似，但前者返回值，而後者不返回任何值。
用法:

public final long getAndSet(int i, long newValue)

參數：該函數接受兩個參數：

i–要進行更新的索引。
newValue–在索引i處設置的值

返回值：函數將在很長的更新之前返回給定索引處的值。

以下示例程序旨在說明上述方法：

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); 
    } 
}

輸出：

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); 
    } 
}

輸出：

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]

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

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注：本文由純淨天空篩選整理自rupesh_rao大神的英文原創作品 AtomicLongArray getAndSet() 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。