Question

我是java的新手，我正在尝试循环使用在main方法中使用增强的for循环创建的HashSet。我得到错误“无效”类型不允许在这里“并且我不太确定如何解决这个问题。我相信对于大多数人来说这似乎是一个简单的错误，但我非常喜欢初学者，所以一些帮助就像这个错误意味着什么以及如何解决它将非常感激。这是代码：

主要课程

package lab5;
public class Main{
    public static void main (String[] args) {
        WordGroup firstWordGroup = new WordGroup("You-can-discover-more-about-a-person-in-an-hour-of-plau-tban-in-a-year-of-conversation");
        WordGroup secondWordGroup = new WordGroup ("When-you-play-play-hard-when-you-work-dont-play-at-all");

        System.out.println("*****First Array list*****");
        String[] firstWordArray =  firstWordGroup.getWordArray();
           for( String word : firstWordArray) { 
              System.out.println(word);
        }
        System.out.println("*****Second Array list*****");
        String[] secondWordArray =  secondWordGroup.getWordArray();
           for( String word : secondWordArray) { 
              System.out.println(word); 
        }
        secondWordGroup.getWordSet(secondWordGroup);
        firstWordGroup.getWordSet(firstWordGroup);

         for (WordGroup pp : secondWordGroup.getWordSet(secondWordGroup)) {
             System.out.println(pp);
        }
    }
}

WordGroup类

package lab5;
import java.util.HashSet;

public class WordGroup {

    String word;

    //Creates constructor which stores a string value in variable "word" and converts this into lower case using the lower case method.
    public WordGroup(String aString) {
        this.word = aString.toLowerCase();
    }
    public String[] getWordArray() {
        String[] wordArray = word.split("-");
        return wordArray;
    }


    public void getWordSet(WordGroup secondWordGroup) {

     HashSet<String> newHashSet = new HashSet<>();

    for (String word : secondWordGroup.getWordArray())
        newHashSet.add(word);

    for (String word : this.getWordArray())
        newHashSet.add(word);
    System.out.println(newHashSet);
    }   
}

Answer 1

更改

public void getWordSet(WordGroup secondWordGroup) {

返回您正在构建的Set<String>，例如

public Set<String> getWordSet(WordGroup secondWordGroup) {

和添加

return newHashSet;

到最后。然后，要使用for-each循环对其进行迭代，它将为String，因此您需要

for (String pp : secondWordGroup.getWordSet(secondWordGroup)) {
    System.out.println(pp);
}

尝试循环HashSet时，不允许使用void类型？

1 个答案: