java - while 循环输入？

Question

我是学习java编程的初学者。基本上，在之前的输入和处理数据之后，我无法弄清楚如何从控制台多次输入输入。在向您展示我的代码之前，我认为最好先展示一下结果应该如何。 程序的结果应该是:

Please Enter either S(supply) or R(replenish) followed by ID and quantity.
R     p122.   10
New Stock-level for p122(Chain) is 58
S.    p124.   20
New Stock-level for p125(Pedal) is 18
S.    p905.   20
No part found with ID p905
.....// enter empty string to terminate

有不同类的用途。我已经能够通过一行输入使我的程序正常工作。

Please Enter either S(supply) or R(replenish) followed by ID and quantity.
R     p122.   10
New Stock-level for p122(Chain) is 58

但是，我不知道如何让用户第二次输入等等。我尝试包含在 while 循环中，但它没有按预期工作。

Please Enter either S(supply) or R(replenish) followed by ID and quantity.
R     p122.   10
//It stops showing the result altogether...

这是我的代码。请告诉我我做错了什么。

import java.util.Scanner;

public class TestPart {
  public static void main(String[] args) {

    // Array of 5 Part objects
    // Part[] part = new Part[5];
    Part[] part = new Part[5];
    part[0] = new Part("p122", "Chain", 48, 12.5);
    part[1] = new Part("p123", "Chain Guard", 73, 22.0);
    part[2] = new Part("p124", "Crank", 400, 11.5);
    part[3] = new Part("p125", "Pedal", 3, 6.5);
    part[4] = new Part("p126", "Handlebar", 123, 9.50);

    ///////// Test Class 2 ////////
    Scanner scanner = new Scanner(System.in);
    System.out.println("Please Enter either S (supply) or R (replenish) followed by ID and quantity.");
    while(!scanner.nextLine().equals("")){

    String sOrR = scanner.next();
    String inputId = scanner.next();
    int amount = scanner.nextInt();
    System.out.println(sOrR);

    for (int i = 0; i < 5; i++) {
        String id = part[i].getID();
        // Find ID in array
        if (id.equals(inputId)) {
            // S or R
            if (sOrR.equals("R")) {
                part[i].replenish(amount);
            } else {

                part[i].supply(amount);

            }
            System.out.println("New Stock-level for " + part[i].getID() + "(" + part[i].getName() + ") is "
                    + part[i].getStockLevel());
        }


    }
    if ((inputId.equals(part[0].getID()) == false) && (inputId.equals(part[1].getID()) == false)
            && (inputId.equals(part[2].getID()) == false) && (inputId.equals(part[3].getID()) == false)
            && (inputId.equals(part[4].getID()) == false)) {
        System.out.println("No part found with ID " + inputId);
    }

    }

    }
}

Answer 1

替换这一行:

while(!scanner.nextLine().equals("")){

与:

while(scanner.hasNext()){

否则您已经在测试中跳转到 nextLine()。