public class Mugs {
Mug mug1;
Mug mug2;
{
mug1 = new Mug(1);
mug2 = new Mug(2);
}

Mugs() {
System.out.println("Mugs");
}

Mugs(int i) {
System.out.println("Mugs[i]");
}
public static void main(String[] args){
System.out.println("Inside main()");
new Mugs();
System.out.println("new Mugs() completed");
new Mugs(1);
System.out.println("new Mugs(1) completed");
}
}

class Mug {
Mug(int marker) {
System.out.println("Mug(" + marker + ")");
}

void f(int i) {
System.out.println("f(" + i + ")");
}
}

结果：

Inside main()
Mug(1)
Mug(2)
Mugs
new Mugs() completed
Mug(1)
Mug(2)
Mugs[i]
new Mugs(1) completed

非静态实例初始化