Java AtomicReferenceArray getAndUpdate()用法及代碼示例

AtomicReferenceArray類的getAndUpdate()方法用於原子更新，該更新通過對當前值應用指定的updateFunction操作來更新AtomicReferenceArray的當前值。它以updateFunction接口的對象為參數，並將該對象中指定的操作應用於當前值。它返回先前的值。

用法:

public final E 
  getAndUpdate(int i, 
    UnaryOperator<E> updateFunction)

參數：此方法接受：

索引i以更新索引值，並且
updateFunction這是沒有副作用的函數。

返回值：此方法返回prevoius值。

以下示例程序旨在說明getAndUpdate()方法：
程序1:

// Java program to demonstrate 
// AtomicReferenceArray.getAndUpdate() method 
  
import java.util.concurrent.atomic.*; 
import java.util.function.UnaryOperator; 
  
public class GFG { 
    public static void main(String args[]) 
    { 
        // an array 
        String a[] 
            = { "GFG", "JS", 
                "PYTHON", "JAVA" }; 
  
        // AtomicReferenceArray with array 
        AtomicReferenceArray<String> array 
            = new AtomicReferenceArray<>(a); 
  
        // Print AtomicReferenceArray 
        System.out.println( 
            "The AtomicReferenceArray before update:"
            + array); 
  
        // Index 
        int index = 2; 
  
        // Declaring the accumulatorFunction 
        // applying function 
        UnaryOperator add 
            = (u) -> u.toString() + " and ML"; 
  
        // apply getAndUpdate() 
        String value 
            = array.getAndUpdate(index, 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 
// AtomicReferenceArray.getAndUpdate() method 
  
import java.util.concurrent.atomic.*; 
import java.util.function.UnaryOperator; 
  
public class GFG { 
    public static void main(String args[]) 
    { 
        // an array 
        Integer a[] = { 213, 1234, 4543, 345 }; 
  
        // AtomicReferenceArray with array 
        AtomicReferenceArray<Integer> array 
            = new AtomicReferenceArray(a); 
  
        // Print AtomicReferenceArray 
        System.out.println( 
            "The AtomicReferenceArray"
            + " before update:"
            + array); 
        // Index 
        int index = 2; 
  
        // Declaring the accumulatorFunction 
        // applying function 
        UnaryOperator add 
            = (u) -> Integer.parseInt(u.toString()) * 200; 
  
        // apply getAndUpdate() 
        int value = array.getAndUpdate(index, add); 
  
        // print AtomicReferenceArray 
        System.out.println("previous value of index 2:"
                           + value); 
        System.out.println("updated value of index 2:"
                           + array.get(2)); 
        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#getAndUpdate(java.util.function.UnaryOperator)

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注：本文由純淨天空篩選整理自AmanSingh2210大神的英文原創作品 AtomicReferenceArray getAndUpdate() 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。