Question

我在所有其他应用程序中都有循环，但这似乎无法正常工作。

int i;
BYTE cy; // carry flag
for (cy=1,i=n-1;(i>=0)&&(cy);i--) // process all words from LSW to MSW
 {
 x[i] = (x[i]-cy)&0xFF; // y[i] = sbc x[i],0
 if (x[i]==0xFF) cy=1; // carry
 }

即使我将它设置为false，它也会不断重复loop3。之后它应该回到主菜单，但它不会。

我试图隔离问题，没问题。我一直在看代码一小时，我似乎无法找到任何问题。有人知道吗？

孤立的问题：

public void loanBook() {
    boolean loop3 = true;
    System.out.println("So you wanna loan a book? Excellent choice.");
        while (loop3) {
            for (int i=0; i<books.size(); i++) {

                System.out.println("Search for the book you're looking for: ");
                String book = in.nextLine();

                if (books.get(i).toString().contains(book) == true) {
                    System.out.println("Looking for: " + books.get(i).toString() + "?");
                    System.out.println("press y to loan book or n to try again");
                    String choice1 = in.next();
                    if (choice1.equalsIgnoreCase("y")) {
                        for (int j=0; j<customers.size(); j++) {
                            if (customers.get(j).getSignedIn() == true) {
                                customers.get(j).booksLoaned.add(books.get(i)); 
                                Timer.delayFunction();
                                System.out.println(customers.get(j).printBookList()); 
                                System.out.println("Returning to main menu");
                         ---->   loop3 = false;  doesnt work for some reason       
                            }
                        }
                    }
                }
            } 
        System.out.println("Couldnt find book");
        }
    }

我的系统输出打印工作正常，所以我知道它正确地通过我的循环。

Answer 1

你有3个嵌套循环。当loop3变为false时，另一个循环（while循环）终止。

但是，您要将loop3设置为最内圈的false深度，这意味着while循环不会检查loop3的值，直到2内循环完成。

如果你想要从所有循环中断，你需要一些中断语句和/或附加条件。例如：

    while (loop3) {
        for (int i=0; i<books.size() && loop3; i++) {

            System.out.println("Search for the book you're looking for: ");
            String book = in.nextLine();

            if (books.get(i).toString().contains(book)) {
                System.out.println("Looking for: " + books.get(i).toString() + "?");
                System.out.println("press y to loan book or n to try again");
                String choice1 = in.next();
                if (choice1.equalsIgnoreCase("y")) {
                    for (int j=0; j<customers.size() && loop3; j++) {
                        if (customers.get(j).getSignedIn()) {
                            customers.get(j).booksLoaned.add(books.get(i)); 
                            Timer.delayFunction();
                            System.out.println(customers.get(j).printBookList()); 
                            System.out.println("Returning to main menu");
                            loop3 = false;    
                        }
                    }
                }
            }
        } 
        System.out.println("Couldnt find book");
    }

当loop3变为false时，这将留下两个内部循环，这将允许外循环立即终止。

Answer 2

您希望在将其设置为false后立即退出while循环。你可以用标签

来做到这一点

public void loanBook() {
    boolean loop3 = true;
    System.out.println("So you wanna loan a book? Excellent choice.");
        while (loop3) {
            outerloop: // added
            for (int i=0; i<books.size(); i++) {

            System.out.println("Search for the book you're looking for: ");
            String book = in.nextLine();

            if (books.get(i).toString().contains(book) == true) {
                System.out.println("Looking for: " + books.get(i).toString() + "?");
                System.out.println("press y to loan book or n to try again");
                String choice1 = in.next();
                if (choice1.equalsIgnoreCase("y")) {
                    for (int j=0; j<customers.size(); j++) {
                        if (customers.get(j).getSignedIn() == true) {
                            customers.get(j).booksLoaned.add(books.get(i)); 
                            Timer.delayFunction();
                            System.out.println(customers.get(j).printBookList()); 
                            System.out.println("Returning to main menu");
                             loop3 = false;
                             break outerloop; // added     
                        }
                    }
                }
            }
        } 
    System.out.println("Couldnt find book");
    }
}

布尔循环不会设置false

2 个答案: