In Java

Write a program that launches 1,000 threads. Each thread adds 1 to a variable named sum that initially is 0. You need to pass sum by reference to each thread. In order to pass it by reference, define an Integer wrapper object to hold sum. Create Runnable class first. sum should NOT be a local variable in the Runnable class.

Part 1: Write and run the program without synchronization to see its effect.

Part 2: Write and run the program with synchronization to see its effect. Synchronization should make the use of shared variable sum thread safe.

Part 1 and part 2 should be separated (2 classes).