Java 中的 AtomicIntegerArray getAndDecrement()方法,示例

原文:https://www . geeksforgeeks . org/atomicntegerarray-getandreduction-method-in-Java-with-examples/

Java . util . concurrent . atomic . atomicntegerarray . GetAndDefault()是 Java 中的一个内置方法,它会自动将给定索引处的值递减 1。该方法获取 AtomicIntegerArray 的索引值,并返回该索引处的值,然后递减该索引处的值。函数getanddecadel()decadend get()类似,但后者返回减量后的值,而前者返回减量前的值。

语法:

public final int getAndDecrement(int i)

参数:该函数接受单个参数 i ,该参数是执行减 1 操作的索引。

返回值:该函数返回减量操作前在 int 中的索引处的值。

以下程序说明了上述方法: 程序 1:

// Java program that demonstrates
// the getAndDecrement() function

import java.util.concurrent.atomic.AtomicIntegerArray;

public class GFG {
    public static void main(String args[])
    {
        // Initializing an array
        int a[] = { 1, 2, 3, 4, 5 };

        // Initializing an AtomicIntegerArray with array a
        AtomicIntegerArray arr = new AtomicIntegerArray(a);

        // Displaying the AtomicIntegerArray
        System.out.println("The array : " + arr);

        // Index where operation is performed
        int idx = 3;

        // Decrementing the value at
        // idx applying getAndDecrement
        // and storing previous value
        int prev = arr.getAndDecrement(idx);

        // The previous value at idx
        System.out.println("Value at index " + idx
                           + " before decrement is "
                           + prev);

        // Displaying the AtomicIntegerArray
        System.out.println("The array after decrement : "
                           + arr);
    }
}

Output:

The array : [1, 2, 3, 4, 5]
Value at index 3 before decrement is 4
The array after decrement : [1, 2, 3, 3, 5]

程序 2:

// Java program that demonstrates
// the getAndDecrement() function

import java.util.concurrent.atomic.AtomicIntegerArray;

public class GFG {
    public static void main(String args[])
    {
        // Initializing an array
        int a[] = { 10, 20, 30, 40, 50 };

        // Initializing an AtomicIntegerArray with array a
        AtomicIntegerArray arr = new AtomicIntegerArray(a);

        // Displaying the AtomicIntegerArray
        System.out.println("The array : " + arr);

        // Index where operation is performed
        int idx = 0;

        // Decrementing the value at
        // idx applying getAndDecrement
        // and storing previous value
        int prev = arr.getAndDecrement(idx);

        // The previous value at idx
        System.out.println("Value at index " + idx
                           + " before decrement is "
                           + prev);

        // Displaying the AtomicIntegerArray
        System.out.println("The array after decrement : "
                           + arr);
    }
}

Output:

The array : [10, 20, 30, 40, 50]
Value at index 0 before decrement is 10
The array after decrement : [9, 20, 30, 40, 50]

参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/concurrent/atomic/atomicintegerarray . html # getandreduction(int)