Question

我不知道该如何处理“每个循环”。

我正试图将所有人口加起来。

每次循环我都会收到错误消息。

错误显示“无法应用于给定类型”

有人可以帮我吗？

import java.util.ArrayList;

public class Canada
{
    private ArrayList<ProvinceTerritory> provinces;

    public Canada()
    {
       provinces = new ArrayList<ProvinceTerritory>();

       provinces.add(null);
       provinces.add(new ProvinceTerritory("Ontario",12851821));
       provinces.add(new ProvinceTerritory("Quebec",7903001));
       provinces.add(new ProvinceTerritory("British Columbia",4400057));
       provinces.add(new ProvinceTerritory("Alberta",3645257));
       provinces.add(new ProvinceTerritory("Manitoba",1208268));
       provinces.add(new ProvinceTerritory("Saskatchewan",1033381));
       provinces.add(new ProvinceTerritory("Nova Scotia",921727));
       provinces.add(new ProvinceTerritory("New Brunswick",751171));
       provinces.add(new ProvinceTerritory("Newfoundland and Labrador",514536));
       provinces.add(new ProvinceTerritory("Prince Edward Island",140204));
       provinces.add(new ProvinceTerritory("Northwest Territories",41462));
       provinces.add(new ProvinceTerritory("Yukon",33987));
       provinces.add(new ProvinceTerritory("Nunavut",31906));

    }

    public int getTotalPopulation()
    {
        int sum = 0;

        for(ProvinceTerritory tempT : provinces)
        {
            if (tempT != null)
            {
                sum += tempT.getPopulation();
                System.out.println(sum);
            }
        }
        return sum;
    }
}

这是“ ProvinceTerritory”类代码

public class ProvinceTerritory
{

    String  name;
    int     population;

    public ProvinceTerritory(String name, int population)
    {
        if(name != null)
        {
            this.name = name;
        }
        else
        {
            throw new IllegalArgumentException ("cant be null");
        }

        if(population >0)
        {
            this.population = population;
        }
        else
        {
            throw new IllegalArgumentException ("Can not be -ve");
        }    
    }



    public String getName(String Province)
    {
        if (Province != null)
        {
            this.name = Province;
        }
        else
        {
            throw new IllegalArgumentException ("cant be null");
        }
        return this.name;
    }


    public int getPopulation(int People)
    {
        if (People >0)
        {
            this.population = People;
        }
        else
        {
            throw new IllegalArgumentException ("cant be -ve");
        }
        return this.population;
    }
}

任何帮助将不胜感激

Answer 1

问题是您没有int getPopulation()。这就是为什么在尝试致电tempT.getPopulation()

时出现错误的原因

相反，您有一个int getPopulation(int)，它很奇怪地尝试同时充当设置者和获取者。

您可以用tempT.getPopulation(0)来调用它，但是最好将其替换为普通的吸气剂：

public int getPopulation()
{
    return this.population;
}

为每个循环添加所有人口

1 个答案: