Java 小代码问题 Java编程

public class Something {
public static void main(String[] args) {
Something s = new Something();
System.out.println("s.doSomething()returns"+doSomething());

}
public static String doSomething(){
    return"DO something...";


}

}

为什么加static 静态块 syso里面的doSomething()就能通过