Question

我需要帮助完成学校作业的代码：

制作一个用户可以选择的菜单并允许他们选择哪个循环练习选项运行。以下循环将永远运行直到用户输入一个退出选项int choice;
while(true) { 
    System.out.println(“Please enter in a choice, 0 to quit”); 
    choice = input.nextInt(); //assumes a Scanner object has been created 
    if (choice == 0) {
        break; 
    } 
}

到目前为止，这是我的代码：

import java.util.Scanner;

public class Christmas3 {
    public static void main(String[] args) { 
        Scanner one = new Scanner(System.in);
        int on,tw;
        System.out.println("Enter 1 to execute loop one, 2 to execute loop two or 3 to exit");
        on = one.nextInt();
        while (on == 1) {
            System.out.println("Please enter 1 to confirm the loop or 0 to exit"); 
            tw = one.nextInt(); 
            if (tw == 0) {
                break; 
            }
        }
        for(int i = 0; on > i; on++) {
            System.out.print(" "+on + ", "); 
        } 
        while (on == 2) { 
            System.out.println("Please enter 2 to confirm the loop or 0 to exit"); 
            tw = one.nextInt(); 
            if (tw == 0) {
                break; 
            }
            for(int j = 0; on > j; on = on + 10){
                System.out.print(" " + on  + ", "); 
            }

            if (on == 3) {
                break;
            }
        }
        one.close();
    }
}

我不知道如何执行以下部分＆＃34;以下循环将一直运行，直到用户输入退出选项int choice;＆＃34;

感谢。

Answer 1

public static void printMyInstructions()
{
    System.out.println("Enter 1 to execute loop one, 2 to execute loop two or 3 to exit");

}

public static void main( String[] args )
{
    Scanner myInput = new Scanner(System.in);
    int userChoice = -1 , exitChoice = 3;
    while( userChoice != exitChoice )
    {
        printMyInstructions();
        userChoice = myInput.nextInt();
        analyzeChoice( userChoice );
    }
}

public static void analyzeChoice( int enteredUserChoice )
{
    if( enteredUserChoice == 1 )
    {
        // Do Something
    }
    else if( enteredUserChoice == 2 )
    {
        // Do Something
    }
    else if( enteredUserChoice == 3 )
    {
        System.out.println("Bye Bye");
    }
    else
    {
        System.out.println("Can't really tell what to do with this Option: " + enteredUserChoice);
    }
}

Answer 2

这是你要找的吗？

import java.util.Scanner;

public class Loops {
    public static void main(String[] args) { 
        Scanner input = new Scanner(System.in);
        for (;;) {
            System.out.println("\nMain: Enter 1 to execute loop one, 2 to execute loop two or 3 to exit");
            switch (input.nextInt()) {
            case 1:
                for (boolean loopExit = false;!loopExit;) {
                    System.out.println("Loop 1: Please enter 1 to confirm the loop or 0 to exit"); 
                    switch (input.nextInt()) {
                    case 0:
                        loopExit = true;
                        break;
                    case 1:
                        System.out.println("Loop 1: Confirmed!");
                        break;
                    default:
                        System.out.println("Loop 1: ?Unrecognized input");
                        break;
                    }
                }
                System.out.println("Exited loop 1");
                break;
            case 2:
                for (boolean loopExit = false;!loopExit;) {
                    System.out.println("Loop 2: Please enter 1 to confirm the loop or 0 to exit"); 
                    switch (input.nextInt()) {
                    case 0:
                        loopExit = true;
                        break;
                    case 1:
                        System.out.println("Loop 2: Confirmed!");
                        break;
                    default:
                        System.out.println("Loop 2: ?Unrecognized input");
                        break;
                    }
                }
                System.out.println("Exited loop 2");
                break;
            case 3:
                input.close();
                System.exit(-1);
                break;
            default:
                System.out.println("?Unrecognized input");
                break;
            }
        }
    }
}

试图理解for（）和while（）循环

2 个答案: