如何在没有System.exit的情况下退出Java程序？（来自用户输入？）
这是我的代码。 我不知道如何使用返回值退出程序。 有任何想法吗？ 这是我任务的最后一步。 重要区域标有///////我听到返回工作但是当我将main中的void更改为int时，程序说main必须是void。
import java.util.Scanner; public class CommissionCalculator { public static void main(String args[]) { // Initialize a Scanner to read input from the command line Scanner ItemSelect = new Scanner(System.in); double comp = 200.00; double item1 = 239.99; double item2 = 129.75; double item3 = 99.95; double item4 = 350.89; double comm = 0.09; int choice; /* Note that we'll be doing this at least once and most likely multiple times... * Prompt the user with a menu of the four items and their values (this information is included in the problem statement) */ System.out.println("Item\tValue"); System.out.println("1\t$239.99"); System.out.println("2\t$129.75"); System.out.println("3\t$99.95"); System.out.println("4\t$350.89"); /* Display the user's current compensation */ System.out.printf("Current compensation: $%.2f", comp); /* * Prompt and take input from the user (you may assume that they will only enter int values) * They'll enter an item number (1 - 4) to record its sale or 0 to exit * * NOTE: THE U0SER DOES NOT ENTER PRICES DIRECTLY... THEY ENTER ITEM NUMBERS TO INDICATE WHAT WAS SOLD * NOTE: THE USER MAY ENTER THE SAME ITEM NUMBRER MULTIPLE TIMES * * If the user provides invalid input (a value other than 0 - 4) display "ERROR: Invalid input!" and prompt them again */ do { System.out.print("\nPlease select an item from the " + "list above (or enter 0 to exit): "); choice = ItemSelect.nextInt(); { if (choice != 1 && choice != 2 && choice != 3 && choice != 4 && choice != 0) { do { System.out.print("ERROR: Invalid Input!\n"); System.out.println("Item\tValue"); System.out.println("1\t$239.99"); System.out.println("2\t$129.75"); System.out.println("3\t$99.95"); System.out.println("4\t$350.89"); System.out.printf("Current compensation: $%.2f", comp); System.out.print("\nPlease select an item from the " + "list above (or enter 0 to exit): "); choice = ItemSelect.nextInt(); if (choice == 1) { comp += (comm * item1); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 2) { comp += (comm * item2); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 3) { comp += (comm * item3); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 4) { comp += (comm * item4); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 0) { System.out.printf("Total Earnings: $%.2f", comp); System.exit(0); /////// } }while (choice != 1 && choice != 2 && choice != 3 && choice != 4 && choice != 0); } else { if (choice == 1) { comp += (comm * item1); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 2) { comp += (comm * item2); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 3) { comp += (comm * item3); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 4) { comp += (comm * item4); System.out.printf("Current compensation: $%.2f", comp); } if (choice == 0) { System.out.printf("Total Earnings: $%.2f", comp); System.exit(0); } } } }while (choice != 0); /* After the user enters 0, display the salesperson's earnings in the format "Total earnings: $NNN.NN" and exit * For example, if the salesperson sold two item 3s this week the final output would be "Total earnings: $217.99" */ if (choice == 0) { System.out.printf("Total Earnings: $%.2f", comp); System.exit(0); /////// } ItemSelect.close(); System.exit(0); /////// } } 只要您不需要返回自定义退出代码（除了0，由System.exit(0)返回）并且不启动新线程，您可以通过执行来终止程序
return;
在你的main()方法中。 请注意，没有返回值，因此您无需将main()方法从void更改为int 。