public class TestSync2 implements Runnable {
int b = 100;

synchronized void m1() throws InterruptedException {
b = 1000;
Thread.sleep(500); //6
System.out.println("b=" + b);
}

synchronized void m2() throws InterruptedException {
Thread.sleep(250); //5
b = 2000;
}

public static void main(String[] args) throws InterruptedException {
TestSync2 tt = new TestSync2();
Thread t = new Thread(tt); //1
t.start(); //2

   tt.m2(); //3
   System.out.println("main thread b=" + tt.b); //4

}

@Override
public void run() {
try {
m1();
} catch (InterruptedException e) {
e.printStackTrace();
}
}