引号怎么用

Question

package yang;    public class hellowworld{       public static void main(String[] args) {            System.out.println("hobby"); }    }这里面System.out.println("hobby");括号里有引号，我把引号去了，显示错误；但如果给hobby赋值加入                         String hobby="我爱慕课网"; System.out.print(hobby);这时候括号内不需要引号，反而加入引号，显示错误