北大青鸟S1JAVA第三章课后练习详解

public class Branch { String subName; int totalBooks; int totalHrs; Branch(String subName1,int totalBooks1) { subName=subName1; totalBooks=totalBooks1; } void calculateHrs() { totalHrs=totalBooks*2; System.out.println(subName+"学科的总时数是："+totalHrs); } public static void main(String[]args) { Branch objB1=new Branch("科学",10); Branch objB2=new Branch("艺术",14); Science objS=new Science(); objS.calculateHrs(objB1); Arts objA=new Arts(); objA.calculateHrs(objB2); } } class Science { void calculateHrs(Branch objB1) { objB1.calculateHrs(); } } class Arts { void calculateHrs(Branch objB2) { objB2.calculateHrs(); } }