java - 如何遍历对象的HashSet并在ToString方法中打印每个对象的String值？

Question

HashSet<Soldier> soldiers;           // it has name, rank, description

@Override
public String toString(){
    return "Team: " + teamName + "\n" + "Rank: " + getRanking(soldiers) + "\n" 
     + "Team Members Names are: "+"\n" + soldiers.iterator().hasNext();
    //last line doesn't work
    // I also tried soldiers.forEach(System.out::println) but doesn't work
}

任何人都可以请教我如何在重写的 toString 方法中打印哈希集中的所有名称。谢谢

Answer 1

如果您使用java 8。使用stream API很简单:

public class Test {

    public static void main(String[] args) {
        Set<String> strings = new HashSet<>();

        strings.add("111");
        strings.add("113");
        strings.add("112");
        strings.add("114");

        String contactString = strings.stream().map(String::toString).collect(Collectors.joining(","));
    }
    
}

如果您想更改分隔符，您应该将 Collections.joining(",") 代码替换为您需要的代码。另请参阅 StringJoiner 提供的文档

对于具有方法 getName() 的类 Soldier:

Set<Soldier> soldiers = new HashSet<>();
String soldierNames = soldiers.stream().map(Soldier::getName).collect(Collectors.joining("\n"));

您将得到下一个结果:

Din

Mark

David

... values from the soldiers set