Test.java

class A {
	static String S = "a:" + B.S;
}
class B {
	static String S = A.S;
}

class Test {
	public static void main(String[] args) {
		if (Math.random() > 0.5) {
			System.out.println(A.S);
			System.out.println(B.S);
		} else {
			System.out.println(B.S);
			System.out.println(A.S);
		}
	}
}