Java AtomicLongArray getAndIncrement()用法及代碼示例

Java.util.concurrent.atomic.AtomicLongArray.getAndIncrement()是Java中的一種內置方法，可以自動將AtomicLongArray的任何索引上存在的值加1。該方法將AtomicLongArray的索引值作為參數，在遞增之前返回該索引處的值，然後在該索引處遞增該值。函數getAndIncrement()與incrementAndGet()函數相似，但前者返回增量前的值，而後者返回增量操作後的值。

用法:

public final long getAndIncrement(int i)

參數：該函數接受單個參數i，該參數是執行一個操作遞增的索引。

返回值：函數將在很長的更新之前返回該索引處的先前值。

以下示例程序旨在說明上述方法：

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); 
    } 
}

輸出：

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); 
    } 
}

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, 15, 15]

注意：函數getAndIncrement()與incrementAndGet()類似，但後一個函數返回更新後的值，而前一個函數在更新後返回前一個值。

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

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