Question

我一直在使用Java进行刽子手游戏。有人为我重新设计了这两种方法然后离开;这些方法必须有效，因为我的程序有效，我不知道他们做了什么。

你可以向我解释这段代码，好像你是为初学者评论它，并提供一个更简单的代码版本（可能更多if-then-elses），保持相同的功能吗？

问题，答案，信息在包含我遇到问题的两种方法的类中声明。

public class Question {
    private final String question;
    private final String answer;
    private final String info;
}

并在此构造函数中初始化...

public Question(String question, String answer, String info) {
    this.question = question;
    this.answer = answer;
    this.info = info;
}

问题1是在一个名为HangmanMain的不同类中声明和初始化的，就像这样...

private static List<Question> initQuestions()  {
    Question question1 = new Question("What is the statement terminating character in Java?", ";", "The semi-colon (;) is used to end a statement in Java.");
}

我遇到问题的两种方法：

public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;

    Question question1 = (Question) o;

    if (answer != null ? !answer.equals(question1.answer) : question1.answer != 
    null) return false;

    if (info != null ? !info.equals(question1.info) : question1.info != null) 
    return false; 

    if (question != null ? !question.equals(question1.question) : 
    question1.question != null) return false;

    return true;
}

public int hashCode() {
    int result = question != null ? question.hashCode() : 0;
    result = 31 * result + (answer != null ? answer.hashCode() : 0);
    result = 31 * result + (info != null ? info.hashCode() : 0);
    return result;
}

Answer 1

equals()方法过于复杂。你真的应该把它分成一个函数，用

之类的东西来测试字段是否相等

    private static boolean equals(String a, String b) {
        if (a == null) {
            return b == null;
        }
        return a.equals(b);
    }

    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (!(o instanceof Question)) {
            return false;
        }

        Question that = (Question) o;
        return (equals(this.answer, that.answer) && //
                equals(this.info, that.info) && //
                equals(this.question, that.question));
    }

然后你可以从hashCode()中删除三元组

    public int hashCode() {
        int result = 0;
        if (question != null) {
            result = question.hashCode();
        }
        if (answer != null) {
            result = 31 * result + answer.hashCode();
        } else {
            result = 31 * result;
        }
        if (info != null) {
            result = 31 * result + info.hashCode();
        } else {
            result = 31 * result;
        }
        return result;
    }

Java，三元运算符，if-then-else

1 个答案: