可能是我沒有寫完整吧,還是我沒有理解好

1 接口

public interface SetAndGetWeight

{

public void setW(double weight);

public double getW();

}

2 類

class Train

{

SetAndGetWeight[] things;

public void Train(SetAndGetWeight[] things)

{

this.things=things;

}

public void returnTotalWeight()

{

double totalweight=0;

for(int i=0;i

{

totalweight=totalweight+things[i].getW();

}

System.out.println("Train總的質量是："+totalweight);

}

}

第3個類

import java.util.Scanner;

class TrainComWeight

{

public static void main(String[] arg)

{

Scanner rd=new Scanner(System.in);

System.out.println("請輸入船上人數：");

int peonum=rd.nextInt();

System.out.println("請輸入船上Tv數：");

int tvnum=rd.nextInt();

System.out.println("請輸入船上COM數：");

int comnum=rd.nextInt();

System.out.println("請輸入船上wash數：");

int washnum=rd.nextInt();

int totalnum=peonum+tvnum+comnum+washnum;

SetAndGetWeight[] things=new SetAndGetWeight[totalnum]; Train tr=new Train(things);

System.out.println("請輸入各個人的體重！");

for(int i=0;i

{

System.out.println("請輸入第"+i+"peo的重量");

things[i].setW(rd.nextDouble());

}

System.out.println("請輸入TV的重量");

for(int j=peonum;j

{

System.out.println("請輸入第"+j+"tv的重量");

things[j].setW(rd.nextDouble());

}

System.out.println("請輸入COM的重量");

for(int k=peonum+tvnum;k

{

System.out.println("請輸入第"+k+"CIN的重量");

things[k].setW(rd.nextDouble());

}

System.out.println("請輸入WASH的重量");

for(int l=peonum+tvnum+comnum;l

{

System.out.println("請輸入第"+l+"WASH的重量");

things[l].setW(rd.nextDouble());

}

//System.out.println(train)

}

}

其中紅色的地方Train tr=new Train(things);會報錯"找不到符號"