在if语句中使用递归时，在方法中使用递归时的奇怪行为。Java
在if语句中使用递归时，在方法中使用递归时的奇怪行为。Java
提问于 2018-08-26 01:29:17
在通过在线课程学习Java的同时，我还尝试了一些使用本教程编写的代码。有一种方法，它应该连接“课程”，并在最后打印出来。我想使用递归而不是循环。
private String courses = "";
private int tuitionBalance = 0;
public void enroll() {
System.out.println("Enter course to enroll or \"Q\" to quit.");
Scanner in = new Scanner(System.in);
String course = in.nextLine();
if (!course.equalsIgnoreCase("q")) {
courses = courses + "\n" + course;
tuitionBalance = tuitionBalance + costOfCourse;
enroll();
}
System.out.println("Enrolled in: " + courses);
System.out.println("Tuition balance: " + tuitionBalance);
return; // even with "return", this method executes multiple times after leaving if statement.
}当此方法运行时，它会一直提示输入，直到按下'Q‘为止。串联工作正常。然后它留下"if statement“和(对我来说很奇怪的是)，它运行最后两行println代码的次数与提供的输入一样多。
例如，当我输入三种类型的"course“，然后按'Q'，输出是：
Enter course to enroll or "Q" to quit.
History // My entry
Enter course to enroll or "Q" to quit.
Math // My entry
Enter course to enroll or "Q" to quit.
Biology // My entry
Enter course to enroll or "Q" to quit.
q // My entry
Enrolled in:
History
Math
Biology
Tuition balance: 1800
Enrolled in:
History
Math
Biology
Tuition balance: 1800
Enrolled in:
History
Math
Biology
Tuition balance: 1800
Enrolled in:
History
Math
Biology
Tuition balance: 1800
Process finished with exit code 0你能告诉我发生了什么事吗？
编辑:我已经阅读了Understanding recursion [closed]，但我没有找到任何关于递归如何影响调用堆栈的信息。有很多关于如何使用递归的很好的信息，但我仍然没有找到我的问题的答案。
回答 1
Stack Overflow用户
回答已采纳
发布于 2018-08-26 01:50:50
问题是，您不希望在用户已经进入课程的情况下打印递归，否则一个简单的方法就可以解决问题
private String courses = "";
private int tuitionBalance = 0;
public void enroll() {
System.out.println("Enter course to enroll or \"Q\" to quit.");
Scanner in = new Scanner(System.in);
String course = in.nextLine();
if (!course.equalsIgnoreCase("q")) {
courses = courses + "\n" + course;
tuitionBalance = tuitionBalance + costOfCourse;
enroll();
}
else{//now it would come here only once after user has entered q after which it returns
System.out.println("Enrolled in: " + courses);
System.out.println("Tuition balance: " + tuitionBalance);
}
return;
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/52019653
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