Java 中的 AtomicLongArray getAndDecrement()方法，示例
原文:https://www . geeksforgeeks . org/atomicongarray-getandreduction-method-in-Java-with-examples/
Java . util . concurrent . atomic . atomicongarray . GetAndDefault()是 Java 中的一个内置方法，它会将给定索引处的值自动递减 1。此方法获取 AtomicLongArray 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()与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:
公共最终长 GetAndDefault(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:该函数返回在减量操作之前在位于长的索引处的值。
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.AtomicLongArray;
public class GFG {
public static void main(String args[])
{
// Initializing an array
long a[] = { 1, 2, 3, 4, 5 };
// 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;
// Decrementing the value at
// idx applying getAndDecrement
// and storing previous value
long prev = arr.getAndDecrement(idx);
// The previous value at idx
System.out.println("Value at index " + idx
+ " before decrement is "
+ prev);
// Displaying the AtomicLongArray
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.AtomicLongArray;
public class GFG {
public static void main(String args[])
{
// Initializing an array
long a[] = { 10, 20, 30, 40, 50 };
// 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;
// Decrementing the value at
// idx applying getAndDecrement
// and storing previous value
long prev = arr.getAndDecrement(idx);
// The previous value at idx
System.out.println("Value at index " + idx
+ " before decrement is "
+ prev);
// Displaying the AtomicLongArray
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]
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