Question

我有一个HashSet<String>，其中包含名为shingles的字符串（如果您使用字符串＆＃34; Fizzbuzz＆＃34;并将其分解为带状疱疹，您可以＆＃39; d得到＆＃34; Fi＆＃34;，＆＃34; iz＆＃34;，＆＃34; zz＆＃34;，＆＃34; zb＆＃34;，＆＃34; bu＆＃34;，＆＃34; uz＆＃34;，＆＃34; zz＆＃34;。不重要，但这就是这个背景下的一块木瓦。）

我试图通过以下方法返回一串HashSet的内容：

public String getShinglesAsString() {
    String shingles = "";
    for (String shingle : this.shingles) {
        shingles += shingle + " ";
    }

    return shingles;
}

for (String shingle : this.shingles)抛出ClassCastException。具体邮件为Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.CharSequence。

我也尝试过使用Iterator对象，我也遇到了同样的问题。这是我从代码输入到构造函数的字符串生成带状疱疹的代码：

// Will generate a new set of shingles based on sentence
public void generateShingles() {
    shingles = new HashSet<>();

    for (int i=0; i<getSentence().length()-1; i++) {
        getShingles().add(getSentence().charAt(i) + getSentence().charAt(i+1));
    }
}

编辑：这是minmal, complete, verifiable example:

public class SentenceWithShingles {
private String sentence;
private Set<String> shingles;

// Constructor
public SentenceWithShingles(String sentence) {
    this.sentence = sentence;
    generateShingles();
}

// Will generate a new set of shingles based on sentence
public void generateShingles() {
    shingles = new HashSet<>();

    for (int i=0; i<getSentence().length()-1; i++) {
        getShingles().add(getSentence().charAt(i) + getSentence().charAt(i+1));
    }
}

public void setSentence(String sentence) {
    this.sentence = sentence;
}

public Set getShingles() {
    return shingles;
}

public String getShinglesAsString() {
    String shingles = "";
    for (String shingle : this.shingles) {
        shingles += shingle + " ";
    }

    return shingles;
}

}

Answer 1

错误在于：

getShingles().add(getSentence().charAt(i) + getSentence().charAt(i+1));

该行将两个字符加在一起。没有连接它们。

getShingles().add(getSentence().charAt(i) + "" + getSentence().charAt(i+1));

将强制使用正确的语义。

迭代HashSet时出现ClassCastException

1 个答案: