我有 2 个并发数据结构，我想以原子方式更新它们

Question

How to make sure that these two concurrent data structure statements get executed as an atomic block without using synchronized statement so that the sum is consistent at any given point in time?

Note : I am new to multi-threading in java.

AtomicLong sumOfAllItems=new AtomicLong();
AtomicLong itemSpecificSum=new AtomicLong();

public void addPrice(long price){
    // how to make sure that these two statements get executed 
    // with synchronised() block

    sumOfAllItems.addAndGet(price);
    itemSpecificSum.addAndGet(price);
}

Answer 1

Change your method from this:

public void addPrice(long price) {
    // ...    
}

to this:

public synchronized void addPrice(long price) {
    // ...    
}

By designating the method as sychronized , the JVM will allow no more than one thread at a time to execute that method.

There are other ways of writing thread safe code, but unless and until you have a specific reason to use them, using synchronized it great – it's simple, correct, and easy to understand / reason about.