如何重置对象循环“计数器”？

Posted 2023-03-31

【中文标题】如何重置对象循环“计数器”？

【英文标题】：How do i reset Object loop "counter"?

【发布时间】：2021-12-09 15:48:19

【问题描述】：

如何在“if”语句为真后重新设置“city”对象并重新启动“for”语句？

private SortedSet<City> cityList;
for(City city:this.cityList)
        
            if(city.getPopulation()==arr[i])
            
                System.out.printf(city.getName() + "(" + city.getCountry() + ") population: " + city.getPopulation() + " area: " + city.getArea());
                i++;
            
        

【问题讨论】：

您使用了不同类型的循环。增强的 for 循环对您隐藏了它的迭代器，因此您无法重置它。

@azurefrog 如何将循环转换为带有 i 计数器的循环？

【参考方案1】：

这是你想要完成的吗？

import java.util.Set;

public class City 

    public static void main(String[] args) 
        Integer[] arr =  50_000, 100_000, 200_000 ;
        Set<City> cityList = Set.of( //
                new City(100_000, "city1", "country1", "area1"), //
                new City(200_000, "city2", "country2", "area2"), //
                new City(350_000, "city3", "country3", "area3") //
        );

        outer: for (int i = 0; i < arr.length; i++) 
            for (City city : cityList) 
                if (city.getPopulation() == arr[i]) 
                    System.out.println(city.getName() + "(" + city.getCountry() + ") population: "
                            + city.getPopulation() + " area: " + city.getArea());
                    continue outer;
                
            
        
    

    private int population;
    private String name;
    private String country;
    private String area;

    public City(int population, String name, String country, String area) 
        this.population = population;
        this.name = name;
        this.country = country;
        this.area = area;
    

    public int getPopulation() 
        return population;
    

    public void setPopulation(int population) 
        this.population = population;
    

    public String getName() 
        return name;
    

    public void setName(String name) 
        this.name = name;
    

    public String getCountry() 
        return country;
    

    public void setCountry(String country) 
        this.country = country;
    

    public String getArea() 
        return area;
    

    public void setArea(String area) 
        this.area = area;
    

嵌套循环时，您可以为它们添加标签 (https://www.tutorialspoint.com/break-continue-and-label-in-Java-loop)

【讨论】：

谢谢！终于工作了。

再想一想，你甚至不需要标签。您可以通过替换“继续外部”来“打破”内部循环；使用“break”并删除“outer：”标签