Java AtomicReferenceArray getAndAccumulate()用法及代碼示例

AtomicReferenceArray類的getAndAccumulate()方法用於原子更新AtomicReferenceArray索引i處的元素，並將給定的accumulatorFunction應用於當前值和給定值，並返回前一個值。 accumulatorFunction應該沒有副作用，因為當嘗試更新由於線程之間的爭用而失敗時，可能會重新應用accumulatorFunction。應用該函數時，將索引i處的當前值作為其第一個參數，並將給定的update作為第二個參數。

用法:

public final E getAndAccumulate(int i, E x,
     BinaryOperator<E> accumulatorFunction)

參數：此方法接受：

i這是執行操作所接受的AtomicReferenceArray的索引，
x這是更新的值，
accumulatorFunction這是兩個參數的無副作用函數。

返回值：此方法返回前一個值。

以下示例程序旨在說明getAndAccumulate()方法：
程序1:

// Java program to demonstrate 
// getAndAccumulate() method 
  
import java.util.concurrent.atomic.*; 
import java.util.function.BinaryOperator; 
  
public class GFG { 
    public static void main(String args[]) 
    { 
        // an array 
        Integer a[] 
            = { 123, 1232, 1433, 134, 13415, 1343 }; 
  
        // AtomicReferenceArray with array 
        AtomicReferenceArray<Integer> array 
            = new AtomicReferenceArray<>(a); 
  
        // Print AtomicReferenceArray 
        System.out.println( 
            "The AtomicReferenceArray before update:"
            + array); 
  
        // Index and Value to apply getAndAccumulate 
        int index = 2; 
        int E = 3; 
  
        // Declaring the accumulatorFunction 
        // applying function 
        BinaryOperator add 
            = (u, v) 
            -> Integer.parseInt( 
                   u.toString()) 
                   * Integer 
                         .parseInt( 
                             v.toString()); 
  
        // apply getAndAccumulate() 
        int value 
            = array.getAndAccumulate(index, E, add); 
  
        // print AtomicReferenceArray 
        System.out.println( 
            "previous value of index 2:"
            + value); 
        System.out.println( 
            "The AtomicReferenceArray after update:"
            + array); 
    } 
}

輸出：

程序2:

// Java program to demonstrate 
// getAndAccumulate() method 
  
import java.util.concurrent.atomic.*; 
import java.util.function.BinaryOperator; 
  
public class GFG { 
    public static void main(String args[]) 
    { 
        // an array 
        String a[] = { "GFG", "JS" }; 
  
        // AtomicReferenceArray with array 
        AtomicReferenceArray<String> array 
            = new AtomicReferenceArray<>(a); 
  
        // Print AtomicReferenceArray 
        System.out.println( 
            "The AtomicReferenceArray before update:"
            + array); 
  
        // Index and Value to apply getAndAccumulate 
        int index = 1; 
        String E = " PYTHON"; 
  
        // Declaring the accumulatorFunction 
        // applying function to add value as string 
        BinaryOperator add 
            = (u, v) -> u.toString() + " and " + v.toString(); 
  
        // apply getAndAccumulate() 
        String value 
            = array.getAndAccumulate(index, E, add); 
  
        // print AtomicReferenceArray 
        System.out.println( 
            "previous value of index 1:"
            + value); 
        System.out.println( 
            "The AtomicReferenceArray after update:"
            + array); 
    } 
}

輸出：

參考文獻： https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/atomic/AtomicReferenceArray.html#getAndAccumulate(int, E, java.util.function.BinaryOperator)

相關用法

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