スレッド範囲内の共有変数の概念と役割

1.

import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class ThreadScopeShareData {

	private static int data = 0;
	private static Map<Thread, Integer> threadData = new HashMap<Thread, Integer>();
	public static void main(String[] args) {
		for(int i=0;i<2;i++){
			new Thread(new Runnable(){
				@Override
				public void run() {
					int data = new Random().nextInt();
					System.out.println(Thread.currentThread().getName() 
							+ " has put data :" + data);
					threadData.put(Thread.currentThread(), data);
					new A().get();
					new B().get();
				}
			}).start();
		}
	}
	
	static class A{
		public void get(){
			int data = threadData.get(Thread.currentThread());
			System.out.println("A from " + Thread.currentThread().getName() 
					+ " get data :" + data);
		}
	}
	
	static class B{
		public void get(){
			int data = threadData.get(Thread.currentThread());			
			System.out.println("B from " + Thread.currentThread().getName() 
					+ " get data :" + data);
		}		
	}
}

2、結果:

Thread-1 has put data :1709985245
A from Thread-1 get data :1709985245
B from Thread-1 get data :1709985245
Thread-0 has put data :-1473073054
A from Thread-0 get data :-1473073054
B from Thread-0 get data :-1473073054