我需要制作一个程序，要求用户输入所有者今天使用的卡车数量，无论卡车是“大”还是“小”，并基本打印出卡车的容量。如果用户在使用else语句后没有输入大或小，我就会遇到问题。教授希望我们请用户再试一次。另外，我对如何打印结果感到困惑，尤其是当用户输入超过2辆卡车时。
这是我的代码：
import java.util.Arrays;
import java.util.Scanner;
public class TomTrucking {
/*
* Complete here if you are using class variables
*/
public static void main(String[]args){
Scanner input = new Scanner(System.in);
System.out.println("How many trucks are operating today (Number of trucks must be 2 or greater)? :");
int t1 = input.nextInt();
if(t1 < 2) {
System.out.println("You entered a value less than 2 for number of trucks.");
System.out.println("Terminating program. ");
System.exit(0);
}else {
double crates = 0;
double crates1 = 0;
String truck;
int i=0;
double array[] = new double[t1];
double array1[] = new double[t1];
for( i = 0; i < array.length; i++ ) {
System.out.println("What is the size of truck " + (i+1) + "(large trucks max crates = 100, small trucks max crates = 10)? ");
truck = input.next();
while(!true) {
if(truck.equals("large")) {
System.out.println("What is the actual number of crates that truck " + (i+1) + " is hauling today (Truck 1 max crates is 100)? ");
crates = input.nextDouble();
boolean ok = true;
array[i] = (crates/100);
}else if(truck.equals("small")){
System.out.println("What is the actual number of crates that truck " + (i+1) + " is hauling today (Truck 2 max crates is 10)? ");
crates1 = input.nextDouble();
boolean ok = true;
array1[i] = (crates1/10)*100;
}else {
System.out.println("Enter either large or small: ");
boolean ok = false;
}
}
System.out.println("**Entry for all trucks completed**");
System.out.println("Truck " + (i-1) + " max: 100 actual: " + crates + " capacity at: " + (array[i-2]) + "%");
System.out.println("Truck " + (i) + " max: 10 actual: " + crates1 + " capacity at: " + (array1[i-2]) + "%");
}
}
}
}
答案 0 :(得分：3)
首先，while循环的条件是
while(!true) {
这意味着循环内的代码将永远不会处理。您可能是说
while(!ok) {
这意味着您必须在循环外部声明ok。
秒，请勿使用System.exit()。这被认为是不良做法。使用布尔标志来控制流。
第三，我建议您使用适当的缩进格式重新设置代码，并使用有意义的变量名称（例如array和array1）。这将帮助您发现错误并帮助我们理解代码。另外，将代码分解为逻辑单元，然后将其放入单独的方法中。例如，一种方法处理用户输入，另一种方法验证用户输入，另一种用于计算，最后一种用于显示结果。
答案 1 :(得分：0)
我发现了一些其他问题，您可以尝试
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("How many trucks are operating today (Number of trucks must be 2 or greater)? :");
int totalTrucks = input.nextInt();
if (totalTrucks < 2) {
System.out.println("You entered a value less than 2 for number of trucks.");
System.out.println("Terminating program. ");
System.exit(0);
} else {
HashMap<Integer, Double> smallTrucks = new HashMap();
HashMap<Integer, Double> largeTrucks = new HashMap();
for (int i = 0; i < totalTrucks; i++) {
System.out.println("What is the size of truck " + (i + 1) + "(large trucks max crates = 100, small trucks max crates = 10)? ");
String truckSize = input.next();
boolean repeatLoop = true;
while (repeatLoop) {
if (truckSize.equals("large")) {
System.out.println("What is the actual number of crates that truck " + (i + 1) + " is hauling today (Truck 1 max crates is 100)? ");
Double crates = input.nextDouble();
largeTrucks.put(i, crates);
repeatLoop = false;
} else if (truckSize.equals("small")) {
System.out.println("What is the actual number of crates that truck " + (i + 1) + " is hauling today (Truck 2 max crates is 10)? ");
boolean sizeWrong=true;
while (sizeWrong) {
Double crates = input.nextDouble();
if (crates > 10) {
System.out.println("Small Truck max crates is 10,Please enter size again ");
repeatLoop = true;
continue;
}
sizeWrong=false;
smallTrucks.put(i, crates);
}
repeatLoop = false;
} else {
System.out.println("Enter either large or small: ");
}
}
}
System.out.println("**Entry for all trucks completed**");
for (int i = 0; i < totalTrucks; i++) {
Double maxTruckSize = smallTrucks.get(i);
if (maxTruckSize != null) {
System.out.println("Truck " + (i + 1) + " max: 100 actual: " + maxTruckSize + " capacity at: " + maxTruckSize / 100 + "%");
}else
System.out.println("Truck " + (i + 1) + " max: 10 actual: " + smallTrucks.get(i)+ " capacity at: " + maxTruckSize / 10 + "%");
}
}
}
答案 2 :(得分：0)
首先要纠正一些错误，然后再将truck = input.next（）移入其中。
我更正了您的代码，并添加了正在运行的程序的输出。但是，如果您坚持使用数组，则在数组未充满输入的情况下打印0。所以我不碰那里。我建议您使用ArrayList而不是array。因此，您可以迭代仅存在的项目。
正常流量：
How many trucks are operating today (Number of trucks must be 2 or greater)? :
2
What is the size of truck 1(large trucks max crates = 100, small trucks max crates = 10)?
large
What is the actual number of crates that truck 1 is hauling today (Truck 1 max crates is 100)?
50
What is the size of truck 2(large trucks max crates = 100, small trucks max crates = 10)?
small
What is the actual number of crates that truck 2 is hauling today (Truck 2 max crates is 10)?
20
**Entry for all trucks completed**
Truck 1 max: 100 actual: 50.0 capacity at: 0.5%
Truck 2 max: 10 actual: 20.0 capacity at: 0.0%
如果用户输入的值与“大”或“小”不同，则重试：
How many trucks are operating today (Number of trucks must be 2 or greater)? :
2
What is the size of truck 1(large trucks max crates = 100, small trucks max crates = 10)?
xxx
Enter either large or small:
What is the size of truck 1(large trucks max crates = 100, small trucks max crates = 10)?
large
What is the actual number of crates that truck 1 is hauling today (Truck 1 max crates is 100)?
50
What is the size of truck 2(large trucks max crates = 100, small trucks max crates = 10)?
small
What is the actual number of crates that truck 2 is hauling today (Truck 2 max crates is 10)?
20
**Entry for all trucks completed**
Truck 1 max: 100 actual: 50.0 capacity at: 0.5%
Truck 2 max: 10 actual: 20.0 capacity at: 0.0%
解决方案：
public static void main(String[]args){
Scanner input = new Scanner(System.in);
System.out.println("How many trucks are operating today (Number of trucks must be 2 or greater)? :");
int t1 = input.nextInt();
if(t1 < 2) {
System.out.println("You entered a value less than 2 for number of trucks.");
System.out.println("Terminating program. ");
System.exit(0);
}
else {
double crates = 0;
double crates1 = 0;
String truck;
int i = 0;
double array[] = new double[t1];
double array1[] = new double[t1];
for( i = 0; i < array.length; i++ ) {
boolean ok = false;
while(!ok) {
System.out.println("What is the size of truck " + (i+1) + "(large trucks max crates = 100, small trucks max crates = 10)? ");
truck = input.next();
if(truck.equals("large")) {
System.out.println("What is the actual number of crates that truck " + (i+1) + " is hauling today (Truck 1 max crates is 100)? ");
crates = input.nextDouble();
ok = true;
array[i] = (crates/100);
}
else if(truck.equals("small")){
System.out.println("What is the actual number of crates that truck " + (i+1) + " is hauling today (Truck 2 max crates is 10)? ");
crates1 = input.nextDouble();
ok = true;
array1[i] = (crates1/10)*100;
}
else {
System.out.println("Enter either large or small: ");
ok = false;
}
}
}
System.out.println("**Entry for all trucks completed**");
System.out.println("Truck " + (i-1) + " max: 100 actual: " + crates + " capacity at: " + (array[i-2]) + "%");
System.out.println("Truck " + (i) + " max: 10 actual: " + crates1 + " capacity at: " + (array1[i-2]) + "%");
}
}
答案 3 :(得分：0)
我不清楚这个问题。但是，仅阅读您的代码，似乎此代码存在多个问题，其中之一是while(!true)中的代码块将永远不会执行。并且您需要在while循环之外声明boolean ok。此代码仍然存在一些逻辑错误。但是由于这是您的课堂作业，请尝试自己找出其余的内容。
boolean ok = false;
while (!ok) {
truck = input.next();
if (truck.equals("large")) {
System.out.println("What is the actual number of crates that truck " + (i + 1) + " is hauling today (Truck 1 max crates is 100)? ");
crates = input.nextDouble();
ok = true;
array[i] = (crates / 100);
} else if (truck.equals("small")) {
System.out.println("What is the actual number of crates that truck " + (i + 1) + " is hauling today (Truck 2 max crates is 10)? ");
crates1 = input.nextDouble();
ok = true;
array1[i] = (crates1 / 10) * 100;
} else {
System.out.println("Enter either large or small: ");
}
}