CS61B的lab1， 求大佬解答

lab1跟着流程走了一遍，但是一直不知道自己的code是对是错，求大佬帮忙看一眼，谢谢！
public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("hello world");
    }
}

/*
1. All code in Java must be part of a class.
2. We delimit the beginning and end of segments of code using { and }.
3. All statements in Java must end in a semi-colon.
4. For code to run we need

*/


public class HelloNumbers {
    public static void main(String[] args) {
        int x = 0;
        while (x < 10) {
            System.out.println(x);
            x = x +1;
        }
    }
}

/*
1. Before Java variables can be used, they must be declared.
2. Java variables must have a specific type.
3. Java variable types can never change.
4. Types are verified before the code even runs!!!
*/