没有System.exit，如何退出Java程序？（通过用户输入？）
这是我的代码。我不确定如何使用返回值退出程序。有任何想法吗？这是我完成任务的最后一步。重要区域标有////////我听到了返回的消息，但是当我将main中的void更改为int时，程序会说main必须为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); ///////
}
}
回答：
只要您不需要返回自定义退出代码（由所返回的0 System.exit(0)除外）并且不启动新线程，就可以通过执行以下操作来终止程序
return;用你的main()方法。请注意，没有返回任何值，因此您无需将main()方法从更改void为int。
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